Thorn Cycles Forum
Community => Muppets Threads! (And Anything Else) => Topic started by: JohnR on October 21, 2021, 06:58:44 pm
-
Last week I did another supported bike trip https://www.bikeadventures.co.uk/product/uk-south-coast-explorer-2021-22/ and have concluded that my Mercury is heavier than needed for such events given the lighter machines used by some of the others. We were very lucky with the weather but that's another matter.
I've tended to add things to the Mercury to make it more versatile and convenient while the bigger tyres (fitted from new) improve comfort. One modest weight-saving measure since my LEJOG was to replace the rack and rack bag with a Carradice saddlebag and Bagman QR which I also felt slightly reduced wind drag (but that might be an illusion). However, I'm starting to run out of other ideas for weight reduction. I'm wondering whether this fork https://www.sjscycles.co.uk/forks/48-650b-thorn-bike-packing-steel-disc-fork-red-imron/ is slightly lighter than the one provided with the bike while during the summer I could try riding without mudguards. The non-approved kickstand is extemely useful although it adds significant weight (why didn't Thorn include a kickstand attachment next to the back wheel of the Mercury? I could also reduce the saddlebag contents on the basis that help can be summoned.
However, I'm wondering whether another, lighter, Rohloff equipped bike (disc brakes also wanted) might be an alternative. I've got another Rohloff bike in the back of the garage which I used for a year but it's a little small for me but could be used as a parts donor in order to keep the cost down. I'd still want tyres of at least 40mm but could leave off the mudguards. I've been looking around and wonder about the Shand Daunder Rohloff https://www.shandcycles.com/shop/bikes/daunder-rohloff/ although it may be too similar in weight to the Mercury. I'm also wondering about the Surly Straggler https://www.spacycles.co.uk/m11b0s143p4208/SURLY-Straggler-Frame-and-Forks-700c (650B also available) which is a relatively cheap frame. It might be no lighter than the Mercury fame but could be the basis for a bike with fewer added bits.
Edit: This frame could be significantly lighter https://www.spacycles.co.uk/m11b0s143p3698/SPA-CYCLES-Titanium-Elan-Frame-Forks-Headset . It looks as if it will take disc brakes.
All comments and suggestions gratefully received.
-
I have to ask " How does your Mercury ride? Is it comfortable ? Does the bike give confidence in the way it handles? A lighter bike from another manufacturer may not provide the same levels of comfort and handling you experience aboard your Mercury and for the sake of a few pounds off the weight of the bike may be of questionable benefit. Saving weight on luggage carried and running quality lightweight tyres suitable for your intended use would be the way to go as a starting point. I'd leave mudguards on unless you know it will either not rain, or you don't mind having a wet backside if it does !
-
What does your Mercury weigh?
The weight of a bike is the sum of weights of the parts.
Some people have looked at my titanium bike and suggested that it must be really light. But, it is a derailleur touring bike, for example I used Velocity Dyad rims, 36 spokes in the rear, a rear hub with a steel axle and quarter inch ball bearings, etc. My rear wheel with tire weighs more than the frame, the bike as a whole is not that light. So, of course it is not that light, I built it up to be a touring bike to carry a load. I built it up to be robust, reliable, easy to repair, parts that are easy to replace, etc. And it has a Brooks sprung saddle. So, it is not that light.
What do your parts weigh?
-
What does your Mercury weigh?
<SNIP>
What do your parts weigh?
mickeg has already asked the two relevant questions.
Your Mercury frame will weigh between 2 - 2.5kg.
You can do whatever you want with your bike, I'm certainly not going to tell anyone any different.
For me, the Mercury is as light as I'd want to go for any touring bike. My Mercury, not yours, if I was looking for a frame to build up like that, I'd have chosen a Nomad. If you want to tour on a Road or Adventure bike, that's fine as well, but there's good reason no one is building them with hub gears. Then there's wheel size, 700c roll faster and there's a fine balance with tyre sizes, wider tyres to compensate for a stiffer fork has a cost in terms of efficiency.
That looks a great organised tour, what bikes were your companions riding? What kit? In what way did you feel disadvantaged?
My other Mercury feels surprisingly more agile than my main one. No guards, lights, dynamo and a lighter Alfine hub, it isn't as versatile, it's good fun, but you can't have everything.
-
Hi John,
Wow sounds like you have a serious case of newbikeitis. :D
On the weight front, as others have said the frame might not be the best place to start.
The unicrown Thorn disc fork you linked might be lighter but I doubt there's much in it.
The Surly frame will use ordinary cro-moly tubing rather than the heat-treated supersteel in the frame you have. Likely it wont feel as lively.
I'm astonished by the liveliness and comfort of the Mercury frame, and with 853 and 725 tubing in fairly fine wall thicknesses and TIG welded, it will be as light as anything made in steel for disc brakes and 40mm+ tures, IMO.
So if I wanted lighter I would be looking at other components and accessories.
There is only so far you can go though.
Marin makes an all-carbon gravel-friendly derailleur drop-bar bike called the Headlands 2 that comes with 700cx40mm tyres.
https://www.bicycling.com/bikes-gear/a32175095/marin-headlands-2-review/
With pedals it weighs about 10kg. Thats no mudguards, rack or lights, and a plastic seat.
My Merc as used weighs 13.8kg. That's with Brooks leather seat, full mudguards, rear rack, hub dynamo and headlamp.
As a rough calculation I reckon I could save 250g on replacing the seat, 550 on dumping the rack, 650 on dumping the mudguards, and 350 on replacing the front hub and dumping the headlamp.
That's a saving of 1.8kg just in swapping for comparable spec, bringing the Merc down to 12kg - or 2kg more than the all-carbon Marin.
You could drop another 500g with an all-carbon fork. And more again with lighter cranks, wheelrims and tyres.
The question is whether it's worth the inconvenience, trouble and expense.
I'm lucky to have a brother who has ridden for years with a club on his carbon-framed road bike, and who also rides with me on an ancient Shogun MTB that weighs significantly more than my Thorn and much more than the carbon-tube Trek I rode previously.
He'll sit and chat to me as I granny up a long climb, then will swap to his middle ring and sprint to the top.
I look at him shrink in the distance and think: shit, that bike's so light. ;D ;D
Then I see the facts staring back at me and they can't be avoided.
-
For a different perspective, my two derailleur randonneur bikes weigh right at 14.5kg dry and unladen. They're my "weapons of choice" for 200-400km/day rides in mixed/pretty hilly terrain due to comfort and how they are equipped for all weather and day/night use for long hours in the saddle.
I've often thought about lighter bikes for the task but these are comfortable over distance and of course I need 32-38mm tires, 3 bottles/cages, at least a rear rack, dyno lighting, my Brooks B.17 saddle, a pump, underseat bag for appropriate tools (usually a multitool, spare tube, patch kit, tire levers), preferably a sus-seatpost if there's a lot of gravel over that distance and mudguards for rain, so it is hard to get the weight much lower.
I have a 10.23kg go-fast bike that is stripped down...two bottle cages, mini-pump and lighter tools, no mudguards or dyno lighting, only battery front-rear blinkies made wholly from Tange Champion No. 1 tubing at 0.8/0.5/0.8 wall thickness. I can manage to get it up to 50kmh on the flat as I can my Fixie, but I tend toward an RA (running average) of 27-33kmh with an AOA (average overall including stops) of about 25kmh no matter what I ride on pavement, so weight hasn't really mattered so much except at the extremes. My Nomad weighs 20kg on the nose dry and unladen and my tandem (which I've also ridden solo on long day rides; it makes a remarkably good day tourer for one person...) weighs 20.86kg. Both of these bikes do end up being my slowest on pavement when ridden unladen, due to the extra weight. They are also the best at handling huge loads -- another whole person plus 4 panniers, a rack-top bag, HB and mid-frame bag plus trailer in the case of the tandem.
I have found the more I ride my bikes, the less I notice the weight. Where I really do notice the difference is when I take the loaded bags off a bike immediately after a tour. What a contrast! The unladen bike then feels like it can fly -- woosh!
Best of luck finding a bike that suits your needs ideally; there's nothing like the feeling of finally getting something wholly right for the intended task.
Dan.
-
One way of taking a bit of weight off a Mercury would be to fit one of Thorn's 853 fork options. But AFAIK they only work for calliper or V-brakes. Which, in themselves, probably weigh a little less than a disc brake.
Springy 853 forks might also allow you to use narrower tyres for the same comfort level, saving a bit more weight on tyres and tubes, although I tend to do the opposite myself and fit the fattest lightweight tyres that still give me adequate mudguard clearance.
As an example of the weights of different tyre options, the difference (for two tyres) between the 622x32 Continental Grand Prix 5000 tyres on my old lightweight bike and the 559x42 Marathon Supremes on my Raven Sport Tour is 390g (would be more if comparing the same wheel size) and there is probably also a saving with the inner tubes. Saving weight in the wheel helps with acceleration and in my opinion makes more difference than elsewhere on the bike.
The 32 mm Continental Grand Prix 5000 tyres are comfortable enough for me on tarmac roads, the main difference I notice is that the 42 mm Marathon Supremes on the Raven Sport Tour are significantly better on tracks and paths.
According to this site: https://www.bicyclerollingresistance.com/ there is also a fairly significant difference in rolling resistance between Continental Grand Prix 5000 (11.4W at 75 psi) and Marathon Supreme (16.9W at 75 psi), which might be a help on group rides. I don't really notice this, as both these tyres are improvements on the ones I had previously on these two bikes.
Going tubeless (if you haven't already) or replacing butyl inner tubes with latex should also provide small gains in weight and/or rolling resistance IF the extra hassle of these options is worth it for you. I've not tried tubeless and don't intend to, but I do use latex tubes in the three bikes that I use for long-distance rides, although my reason for doing so is that I believe they add a bit more comfort as compared to butyl.
-
I have a 10.23kg go-fast bike that is stripped down...two bottle cages, mini-pump and lighter tools, no mudguards or dyno lighting, only battery front-rear blinkies made wholly from Tange Champion No. 1 tubing at 0.8/0.5/0.8 wall thickness.
Same wall thickness Thorn quotes for the Mercury, interestingly.
Thanks for the perspective from your distance bikes, Dan. That's very reassuring. 😄😄
My own outlook when choosing the Merc was that if it turned out to be comfortable, low-stress, low maintenance and still fun I would compensate for the extra couple of kilos pretty quickly with extra strength gained from riding extra miles.
So far that's proven well judged - except that I am having even more fun than I thought.
JohnR, I can barely believe you're dissatisfied with that lovely looking Mercury. It's like watching a man whine about the wife whom all of his friends envy him for. We all know it can't be just the weight - what's really going on? ;)
-
JohnR, the Spa elan you link is a great bike. I test rode one once. It was a fairly heavy build and felt very solid and smooth. For me it was too close to my RST so I bought an audax instead. Neither of these are rohloff designed frames of course.
-
I have a 10.23kg go-fast bike that is stripped down...two bottle cages, mini-pump and lighter tools, no mudguards or dyno lighting, only battery front-rear blinkies made wholly from Tange Champion No. 1 tubing at 0.8/0.5/0.8 wall thickness.
Same wall thickness Thorn quotes for the Mercury, interestingly.
It's pretty much the standard for light touring/Audax bikes, it's no coincidence Thorn's own tubing for their Audax bike is called 858.
That's only part of the story of course, we don't know the butting or how gradual the transition, both will make a significant difference to the feel, as will the modern trend of shaping tubes.
To put it in perspective the common gauge for touring tubes is 0.9/0.6/0.9 with only some super strength tubes going over 1mm. What ought to be obvious is that it only requires a small difference in material quantity (Assuming the designer knows what they're doing) to make a big difference in strength and feel. The weight difference between two steel frames of the same size and geometry can be counted in g rather than kg. Neither I suspect is there anything magical about Reynolds 853, I'm guessing Thorn used it because it's the sort of label people spending that sort of money on a frame expect. There's usually more weight difference between forks, as they're subject to different forces.
I know, I know, I've posted such before and it's becoming a bit of a theme, still it is one of the most talked of subjects across several forums. I went to a frame building demonstration some years ago by well respected British frame builder Dave Yates, he said the two most common questions from potential customers were frame weight and wheelbase, and that they were the least relevant, both are a consequence of getting the important stuff right.
-
Where I really do notice the difference is when I take the loaded bags off a bike immediately after a tour. What a contrast! The unladen bike then feels like it can fly -- woosh!
Dan.
Yes, that feeling is almost worth lugging panniers around for a couple of weeks.
But is it faster, or does it just feel faster? I haven't got the data to know, but suspect any difference is less than it feels.
I know when I had a road bike it always felt faster than the data showed, or the extra speed was a result of extra effort. There's nothing wrong with that, I ride for the experience, if it feels fast it is ;)
-
Thanks for all the comments.
To help understanding of my current situation I attach a photo I took of my Mercury during the recent trip. It would have weighted a bit over 20kg which is around 2kg less than on the LEJOG due to (i) Marathon Almotion tyres with tubes replaced by tubeless G-One Speed and (ii) rack and rack bag replaced by saddlebag with Bagman.
My preferred handlebars (Ergotec AHS) add a bit of weight compared to straight bars with bar ends but I find them to be much more comfortable so they will have to stay. Similarly the Chainglider adds a bit of weight but is too useful. I think a Clickstand https://www.click-stand.com/ would be lighter than a kickstand while I'm not at all keen on the prospect of doing without a disc brake on the front. An alternative to the saddlebag which avoids the 0.4kg of the Bagman merits investigation. I've got the Carridice Maxi saddle pack but don't think it's big enough to hold a warmer top that's not needed at the cooler ends of a day. Slightly narrower tyres might work but the next size down in the G-One Speed in 650B is 30mm which I consder to be very narrow.
Hence my temptation to keep my Mercury pretty much as is for my primary recreational bike (it's clocked up over 7k miles in 15 months) and look for another bike to use with a slightly stripped-down configuration on supported rides with, for example, 700C tyres around 40mm width and no or minimal mudguards.
Would an option to be to investigate whether this Mercury http://thorncyclesforum.co.uk/index.php?topic=14375.0 could be tweaked to fit my needs? My red Mercury is 55L but I'm 5'7" whereas that bike is 520L but the seller 5' 9". I could then join PH in being a dual Mercury owner. ;D
That would still leave me with another Rohloff bike in the garage which I was thinking of scavenging for parts but maybe someone here would be interested in using that bike for a similar purpose.
-
I can't really say what the Mercury frame and fork weigh, I have actually only seen three Thorn bikes of which I own two.
Above, I gave as an example my titanium bike and people thinking it must be light because it has a titanium frame. But all the other stuff I put on the bike weighed it down, it is not a light bike anymore because I used touring weight components and saddle.
Looking at the photo of your bike, I see 32 spoke wheels, not sure how heavy the rims are but they don't look light. Compared to that my road bike has skinny tires, light weight rims and 28 spoke wheels. If you are comparing your bike to a light weight carbon road bike, your wheels and tires look heavy. I see mudguards on the bike. Your Brooks looks heavy.
The bike weight is the sum of the weights of the parts.
I decided years ago not to try to count grams, my bikes are not that light and I do not let that drive my decisions.
-
The rims are Thorn 27.5" 584, the 50mm G-One speed tyres claim to be 515g each while my saddle is a Gilles Berthoud Aravis which has Ti rails and claims to be about 425g. At 5k miles it's getting comfortable.
Another thought. Would a carbon seatpost provide any comfort advantage in addition to some weight reduction?
-
Oops, I thought the saddle was a Brooks. My mistake.
I have no opinion on carbon seatposts, I have no carbon bike components. But I really like my carbon kayak paddle.
-
My preferred handlebars (Ergotec AHS) add a bit of weight compared to straight bars with bar ends but I find them to be much more comfortable so they will have to stay. Similarly the Chainglider adds a bit of weight but is too useful.
I think a few forum members have commented in another thread - maybe another of yours, John - on how it's the non-negotiables that keep bringing the weight up.
FWIW, I'm just back from a trundle of 50km or so and have weighed the bike pretty much as ridden but no food or water bottle, and it came in around 16kg. Plus by then I'd removed my beanie, cable lock, phone, and specs with case - which likely add more than 500g.
On the frame weights PH, what interested me about the comparison of tube wall thicknesses was that the Mercury used the same thickness as the bike Dan had set up as his featherweight, which was within a pound of the carbon-framed Marin I cited.
On the specialness of Reynolds 853, I'm sure the same spec is available from other makers but all this heated-treated stuff is special in so far as the yield strength, and hence the potential for springiness, is way higher than for the softer steels that haven't had the treatment. I think Andy B said somewhere in the megabrochure that the heat-treating more than doubled the price of the tubing. Andre will probably tell us that you can double the price of a product without improving performance and then sell it to suckers if you get the hype right. I find it hard to imagine Andy falling for that one over a decade or more though: much more likely he'd be explaining to us why heat treatment was a waste of time and money. Unless it actually worked.
-
On the specialness of Reynolds 853, I'm sure the same spec is available from other makers but all this heated-treated stuff is special in so far as the yield strength, and hence the potential for springiness, is way higher than for the softer steels that haven't had the treatment.
All steel has pretty much the same springiness (Youngs Modulus), there is some minor variations but I think Reynolds quote the same figure for all their tubes. The feel comes entirely from the shape and dimensions, one steel tube of the same diameter and gauge will feel exactly like another. Of course you can't make the same tubes in any steel, the different strength, both Tensile and Yield, determine what can be done with it.
Heat treating does indeed add a chunk to the cost of a steel, Reynolds offer tubes with and without, 853 is heat treated 631, and I think 725 is heat treated 5??. Thorn's own branded 858 tubing is also heat treated.
OK I'm not a materials scientist, so if anyone knows better I'll correct this, but as far as I'm aware - Thorn 858 tubing will look, feel and behave identical to Reynolds 853 of the same diameter. Any strength differences will only be apparent at the extremes, such as dent resistance or impact (Crash damage)
So why is the Mercury made with Reynolds? Well, we can only guess and mine is - There's a lot of work gone into the Mercury frame, every tube is specific and shaped, it's hard to find a straight edge! Possibly their supplier of Thorn tubing couldn't offer that. But it was always going to be an expensive frame and I suspect the "upgrade" to the Reynolds badge was a smaller percentage of the overall cost than it would have been on a lesser frame.
-
To help understanding of my current situation I attach a photo I took of my Mercury during the recent trip. It would have weighted a bit over 20kg which is around 2kg less than on the LEJOG due to (i) Marathon Almotion tyres with tubes replaced by tubeless G-One Speed and (ii) rack and rack bag replaced by saddlebag with Bagman.
Your bike doesn't look particularly extreme to me. You seem well aware of where the extra weight comes from and have decided it's worth it. It is incremental of course, keep saying X is only a couple of grams and it soon becomes xxx.
Just be careful in the comparison game that it's like with like. I weigh my bikes bare, everything that detaches is before it goes near the scales, bags, tools, bottles, GPS. I don't ride anywhere without at least some of them, but still don't consider them "Bike weight"
So, what do your extras weigh and what difference would not having them make? It seems to me that wouldn't be a hard question for you to answer without spending thousands! The only thing you can't test for yourself is the fork difference, but a steel disc fork is always going to be a disadvantage it terms of weight and comfort (The later can easily be compensated by tyre size, but only by adding to the former)
I could then join PH in being a dual Mercury owner.
It is an exclusive club, I don't know the entry requirements, my application was via the stupidity of riding into the back of a car and I don't recommend that.
If I'd started with a blank sheet, I'd have a 700c Mercury and a 650B Nomad. Those two would ideally cover the riding I currently do on four.
-
It's the wrong time of year for sitting in my chilly garage and trying to weigh each bit on the bike but I agree that all the extra, but useful, bits progressively add weight. It's evident that while 50mm tyres improve comfort they, plus the appropriate mudguards and rims, add weight compared with something narrower (and, I presume, slightly increase the aerodynamic drag). However, while there's a good range of 650b tyres in 50mm or larger, there's limited choice in smaller widths. Schwalbe, for example, seems to jump from 50mm to 30mm or narrower.
Which gets me thinking about having a set of 700c wheels for the Mercury. On paper, I have these sitting on my potential donor bike although there are two potential obstacles: (a) that bike has a belt drive with a screw-on sprocket at the back, which I would need to wrestle off; and (b) the front wheel is QR whereas my Mercury has a 15 x 110mm boost hub. Also, when changing wheels I would need to also change or remove the mudguards which isn't difficult but is a little tedious and regularly swapping between two configurations could get a little boring. I've read a little about carbon seatposts and comments confirm that they help in filtering out vibrations caused by less good road surfaces. Comments about Wiggle's cheapest vary but it seems to be a good starting place.
A second frame with a lighter configuration therefore gets attractive and if the frame, as well as what's on it, is a little lighter then so much the better. As someone already commented, having a bike for guests is no bad thing. Of course, if the total weight of bike plus myself is only reduced by, say, 3kg, then the percentage saving isn't much but if the aerodynamic and rolling performance is also better then perhaps we end up with a bike thats 10% faster and help me keep up with some of those who have faster bikes or are slightly fitter than me. A few kg less also helps get the bike to and from hotel rooms although, with practice, I'm getting better at getting the Mercury up and down stairs (holding it by the seat tube seems to work best).
A lot of this is thinking out loud in the hope that any flaws in my logic will be identified. Am I right in thinking that a Rohloff hub can be fitted on any bike with a rear disc brake provision although, unless it has an EBB or sliding dropouts, it will need a chain tensioner?
-
It's the wrong time of year for sitting in my chilly garage and trying to weigh each bit on the bike
I was thinking more in terms of reconfiguring what you have into the bike you think will make a difference and using it for the sort of tour where you think that worthwhile. Yes some time and effort and also expense, burt even a wheel to suit your fork (Or a fork to suit the wheel) would be an insignificant expense compared to buying a bike and discovering it didn't do what you want.
Am I right in thinking that a Rohloff hub can be fitted on any bike with a rear disc brake provision although, unless it has an EBB or sliding dropouts, it will need a chain tensioner?
There's a way to fit a Rohloff to most dropouts, plenty of detail on the Rohloff website.
The neatest fitting with disc brakes is the Monkeybone, this is what I use on my Airnimal,but it isn't suitable for all. With vertical dropouts, the bolt securing the OEM2 plate has to be behind the dropout so the rotational forces are pushing the hub into the dropout rather than trying to rotate it out! This rules out using a Monkeybone with chainstay mounted disc calipers.
Edit - got my drop outs mixed up :o
-
...
Am I right in thinking that a Rohloff hub can be fitted on any bike with a rear disc brake provision although, unless it has an EBB or sliding dropouts, it will need a chain tensioner?
Check any frame you consider against the Rohloff specificaitons. For example, I do not think that there are any 130mm Rohloffs, for a conventional hub (not through axle, not extra wide, etc.) I think 135mm is the only Rohloff hub option.
Many steel frames that were designed for 130mm can be run with a 135mm hub. My rando bike, I confirmed with the manufacturer that it would work before I ordered the frame. Their only concern was that I would need to pry the stays apart a bit for the wheel to drop it and that might chip the paint. For the five years since I built up that bike, 99 percent of the miles (or km) were with a 135mm hub. I am not using a Rohloff hub in that bike, so I have no comments on torque arms or anything like that.
-
Another perspective:
https://www.youtube.com/watch?v=sDzMrbJTK-U
-
Another perspective:
https://www.youtube.com/watch?v=sDzMrbJTK-U
A very good video. (So drilling holes in my toothbrush handle was pretty pointless.)
-
There's a way to fit a Rohloff to most dropouts, plenty of detail on the Rohloff website.
The neatest fitting with disc brakes is the Monkeybone, this is what I use on my Airnimal,but it isn't suitable for all. With vertical dropouts, the bolt securing the OEM2 plate has to be behind the dropout so the rotational forces are pushing the hub into the dropout rather than trying to rotate it out! This rules out using a Monkeybone with chainstay mounted disc calipers.
Thanks for highlighting this important consideration which I think rules out the Spa Cycles' disc brake frames such as the Elan which mounts the caliper on the chainstay (unless I use the less-than-beautiful torque arm). One remaining candidate is the Surly Straggler frame https://www.spacycles.co.uk/m11b0s143p4208/SURLY-Straggler-Frame-and-Forks-700c which has the caliper mount on the seat stay and what appears to be suitable dropouts to avoid a chain tensioner. The www indicates a few examples of Straggler Rohloffs although there's not much detail.
This exercise is gradually moving from being creation of a lighter Rohloff bike to the rehoming of the useful bits from a bike that's too small into something which would be useful to me or someone of similar size (I've got a couple of friends of similar build whom I keep trying to persuade that Rohloff is the way forward). This doesn't reduce the number of bikes in the garaga but it avoids adding another one.
I attach a photo of the shifter side of the Rohloff on the potential donor bike so you can see what bits are there. It's unclear to me if having a QR axle is a show stopper. While a solid axle would be better with slotted dropouts, the Straggler dropouts do have stop screws to restrain the axle from moving.
-
I'm now a little confused about which way you're thinking of going.
I think you're going to end up with a heavier and lighter build? What I'm not sure of is which the Mercury is going to be!
If you're leaning towards building the other bike as the lighter one and considering non Rohloff specific frames, the Thorn Audax MK4 might be a contender. With discs it'll take 35mm tyres (according to the brochure) but good 32's are probably fine. It's Rohloff ready, I think that means it has somewhere to attach the OEM2 plate, it'll still need a tensioner, it's probably cheaper and IMO better than the Surly, 858 tubing and a quoted frame weight around 2kg.
A QR in horizontal dropouts is fine, just get a good one. My Surly Ogre is a nutted axel but I've seen them built up with QR's. Horizontal dropouts do away with the need for a tensioner at the cost of having to adjust the brakes each time you adjust chain tension, I wouldn't let the difference between them determine a frame, though neither has the convenience of an EBB which would always be my first choice.
-
If you're leaning towards building the other bike as the lighter one and considering non Rohloff specific frames, the Thorn Audax MK4 might be a contender. With discs it'll take 35mm tyres (according to the brochure) but good 32's are probably fine. It's Rohloff ready, I think that means it has somewhere to attach the OEM2 plate, it'll still need a tensioner, it's probably cheaper and IMO better than the Surly, 858 tubing and a quoted frame weight around 2kg.
Thanks for this pointer. That method of restraining the Rohloff hub, and the Audax Mk4 frame being suitable, hadn't crossed my mind. For future reference it's explained at https://www.rohloff.de/en/service/handbook/oem#c27157 . I presume you've previously been through a similar thought process. We might have a way forward although the answer to a question at https://www.sjscycles.co.uk/frames/500-thorn-audax-mk4-disc-frame-gunmetal/ says the weight of a medium frame is 2.46kg but I could pair the frame with disc brake capable carbon forks to help keep the overall weight down. The Spa Cycles Elan 725 frame can accommodate wider tyres but it would be fortutious of the spacing between axle and rack bolt hole was 39.9mm.
The objective is to create both a basic bike (without spending a fortune) that's inherently lighter than the Mercury but one where I would be less inclined to add innumerable extras in order to keep the final weight under control. And, by cannibalising an existing bike, I avoid increasing my collection.
-
If you're leaning towards building the other bike as the lighter one and considering non Rohloff specific frames, the Thorn Audax MK4 might be a contender. With discs it'll take 35mm tyres (according to the brochure) but good 32's are probably fine. It's Rohloff ready, I think that means it has somewhere to attach the OEM2 plate, it'll still need a tensioner, it's probably cheaper and IMO better than the Surly, 858 tubing and a quoted frame weight around 2kg.
...
The objective is to create both a basic bike (without spending a fortune) that's inherently lighter than the Mercury but one where I would be less inclined to add innumerable extras in order to keep the final weight under control. And, by cannibalising an existing bike, I avoid increasing my collection.
If your goal is light weight and if you get a disc frame, if a rim brake fork is lighter you could put a rim brake fork up front, disc in rear.
That is what my titanium bike is, rim brake front and disc rear. I did not do that for weight, I did that because when I bought the frame I already owned the fork that had the right specifications (rake, crown race to axle length, steerer length, wheel size, and max tire width) that I needed. It would have cost me over $400 USD more to put a disc up front than a rim brake, that was my driving decision.
-
I came across this older but recently updated link in my library. Even on a budget it can be costly to reduce weight and even an all-out effort doesn't accomplish much (1-1.3kg)...
https://road.cc/content/buyers-guide/8-cheap-ways-get-lighter-bike-186074
I tend to go by the "full water bottle" principle of saving weight on my bikes. I use 3-5 1l bidons on most of my bikes; some have cages instead for 1-3 1.5l bottles plus 2 1l bottles, so it is easy to simply leave some home in cooler weather. Employing all the measures suggested in the article only saved 1,329g at a cost of £605.05. ??? About the equivalent of one of my bottles. :P
Time for me to buy a few more cases of dehydrated water. ;)
Best,
Dan.
-
After much cogitation, exchanging of emails, measuring, calculation and dithering I decided that the Spa Cycles Elan frame https://spacycles.co.uk/m11b0s143p4590/SPA-CYCLES-Elan-725-Frame-and-Forks was a better fit for my needs than the Thorn Audax frame although there's the problem of providing torque restraint for the Rohloff hub. The primary disadvantage of the Audax frame for me was the limitation of 32mm tyres with mudguards and 35mm without whereas the Elan can accommodate 40mm with mudguards and 50mm without. I've got some 37mm Marathon Mondials which look narrow compared to the 50mm tyres on the Mercury and the prospect of 32mm or narrower tyres was not attractive although I'm not envisaging going above 40mm but i do like my mudguards.
In addition, while the Elan frame is heavier than the Audax, the longer head tube made it possible to achieve my preferred handlebar height using full carbon (including the steerer) forks while respecting the guidance of maximum 40mm of spacers between headset and stem so the extra weight of the frame is offset by lighter forks. I will also admit to being attracted by the Elan's copper paint.
The frame arrived a couple of days ago and I've fitted it out with the available parts so I could discover what I didn't have and which parts I needed for the Rohloff hub. I had long correspondence with John at Spa Cycles regarding the bottom brack size needed with the Spa cranks in order to get a 55mm chainline. I couldn't completely understand his logic but the recommended 122mm bottom bracket proved to be correct with the chainring on the outside of the spider.
One of the attached photos shows the bike in the current condition with brakes, wheels and tyres (the Mondials) off the donor bike. The brake and Rohloff cables are also those off the donor bike and will be replaced. The other attached photo shows the standard Rohloff axleplate in the rear dropout. My plan is to fit a Rohloff support bolt in the upper mudguard / rack hole where it will partly engage with the axleplate and cut a bit out of the side of the axleplate to engage with another normal bolt in the lower hole for further torque restraint in the low gears. However, it remains to be seen how well the axleplate will engage with the support bolt as it also needs to restrain the anti-clockwise torque (as viewed from this side) that occurs in gears 12 - 14. I may be hunting for a short piece of 10mm ID tube which I can fitt over the support bolt so it fits snugly in the end of the groove in the axleplate.
At the moment the copper bike feels a lot lighter than the Mercury but the difference will reduce as I add the remaining fittings and some baggage. I'm thinking of a small saddle bag plus a small bar bag to put some more weight at the front. I encountered a short section of hill when in Cornwall in October which was steep enough for the Mercury's front wheel to lift off the ground in spite of the relatively heavy steel forks.
The project is now on hold pending arrival of the remaining parts which I ordered yesterday.
-
That's going to be an interesting bike. I've looked longingly at those frames since they were first introduced, I really can't justify another bike... A friend has the Ti version and prefers it to his other, more expensive, bikes.
When considering an unconventional Rohloff build, I did consider getting a custom OEM plate shouldn't be exceptionally hard or expensive, but I didn't follow it up.
Cables without guides can also be an issue, aesthetically if nothing else. I've seen a couple of bikes with no outer along the down tube using Problem Solvers backstops
https://problemsolversbike.com/products/brakes/backstop_-_1282
-
I did give a little consideration to the Ti frame but didn't feel I could justify the extra £500 to save about 3/4kg. John at Spa Cycles reminded me more than once that if i wanted a lightweight bike then I shouldn't be weighing it down with a Rohloff hub. Hence my objective of a "less heavy" bike.
A custom axleplate would be the ideal solution and not one I've thought about. Something like this https://get-it-made.co.uk/guides/cnc-machining-guide/ would do the job but would likely need a 3D drawing. Also, while I've got some full-sized mudguards on the way for winter use I've stumbled on, and ordered, these https://www.amazon.co.uk/gp/product/B004R4I6XI for use in the summer. Worth trying at that price!
-
I did give a little consideration to the Ti frame but didn't feel I could justify the extra £500 to save about 3/4kg.
I'd be surprised if it was anything like as much as that, a review in Cycle magazine suggested the difference between Spa's steel and ti tourer was around 300g. The advantages of ti are IMO other than the weight, when I replaced my Raven with a custom ti frame, it was actually heavier! OK it suited me better in all other regards but it kicked into the long grass any ideas I'd had about bike weight.
A custom axleplate would be the ideal solution and not one I've thought about.
I hadn't really got as far as design, though it would probably have modified the most appropriate standard one.
Looking again at your dropouts - having a plate made that utilised both those holes, with a cut out between them for an OEM plate bolt, might be the easiest and neatest solution. plus it would spread the force.
EDIT - While browsing for something else, I've noticed a couple of extended designs of Speedbone/Monkeybone type fittings, I have no idea what these are for or how they're used, but they might be worth investigating.
-
I was told that the weight of a 54cm Elan frame is 2.24kg which I assume is without the headset as my 52cm Elan frame weighed in at 2.46kg with the headset fitted. There's a table at https://spacycles.co.uk/m1b0s223p4501/SPA-CYCLES-Elan-Ti-%28Ultegra-11-Speed-Hydraulic%29 which puts the weight of the 54cm Ti frame as 1.65kg, so it might be 0.59kg lighter than the steel frame. However, the only way to be sure of the weight difference is to go to Harrogate with some scales and get new frames out of boxes to ensure measurements are comparing like for like.
You got me thinking about a custom axleplate and I found this site https://www.machining-4u.co.uk/ together with Rohloff CAD drawings at the bottom of this web page https://www.rohloff.de/en/service/handbook/oem. .stp file are 3D CAD files which I'm able to view using software called ABviewer but none of the axleplates provided seem to represent part 8227. Nonetheless, I might find I can send one of those files plus a sketch of my requirements and get a quote. Editing a Rohloff file to create 8227 with longer fingers and a cut-out on the side should be straightforward for someone with the right software and skills after which it's a matter of telling a machine to carve a lump of metal. However, I'll first wait for SJS to send me a few bits (I've ordered both Rohloff Support Bolt for Axle Plate OEM2 - 8560 and Rohloff OEM2 Adapter for M5 Fender / Luggage Rack Bolt - 8552 to see what fits best) and how much further modification is needed. Rohloff support suggested that the PM bone with corresponding axleplate would work but would shift the brake caliper out so I'd also need a 180mm brake rotor. Hence I'm starting with the parts I've already got.
-
Looks like you've got a few options to work through, there's plenty who have been there before and fond the solution to suit them, I'll follow with interest.
I still think you're over estimating the weight difference between steel and ti, but as you say the only way to know is with a set of scales.
Are you going for the Rohloff tensioner? it's a bit of a lump, but the usual Rohloff quality, I prefer it to the Shimano Alfine equivalent that sometimes allows the chain to skip of rough ground.
-
My Birdy Rohloff has the Rohloff chain tensioner which I feel is a source of extra drag, perhaps not helped by the Birdy's imperfect chainline. Therefore I'm starting off with a cheap chain tensioner https://www.ebay.co.uk/itm/363524913744 but am looking out for a Surly Singleator at a nice price. I've also got an open Chainglider to provide some protection for me and the chain but should have the added benefit of reducing the risk of a loose chain jumping off the chainring. I'm waiting to see how loose the chain is with the frame and the 42 + 17 gearing combination I want. There could be justification in changing to a 41 or 43T chainring or fit a half link if the result is a chain which doesn't jump off without a tensioner and with the extra guidance from the Chainglider. Plenty of options to try. ;D
-
Titanium is light, but the weight of a bike is the sum of the parts. My light touring bike is titanium, but the rest of the bike is built for touring. Touring weight rims, 36 spokes in rear and 32 spokes up front. Steel axle in rear with quarter inch ball bearings. Steel fork. Sprung Brooks saddle. So, although the frame weighs less than the rear wheel with tire mounted, the bike is probably only 5 or 10 percent lighter by being titanium than it would be with steel. But I was not building it to be light, I was building it to be robust, easy to repair, easy to replace components, reliable, etc.
Any tensioner will add drag as a tighter chain increases chain friction and also jockey pulley friction, but the percentage of the total drag that is added by the tensioner is quite small. Drive train drag and tire friction will slow you down much more than an extra kg of weight because weight is not that critical unless you are a racer. If I was trying to build a really light bike that had a Rohloff, I would try to eliminate or minimize tensioner drag as much as possible.
Is there any estimate for chain glider drag? That might slow you down more than an extra kg, but I have seen no data so I am only guessing that it adds several watts of friction.
You will need some way to adjust the chain tension, changing chainring sizes and half links is not the solution.
-
Any tensioner will add drag as a tighter chain increases chain friction and also jockey pulley friction, but the percentage of the total drag that is added by the tensioner is quite small.
A Surly Singleator set pushing up, with just enough tension to prevent the chain from unshipping, adds, IMO, very little friction. I reckon less than a conventional tensioner or derailleur with 2 pulleys. I have this setup on a bike with vertical dropouts and a hub gear.
I still have to clean the single pulley, the presence of a tensioner also prevents me from fitting a Chainglider, so I have to clean the chain, chainring and sprocket regularly.
Is there any estimate for chain glider drag? That might slow you down more than an extra kg, but I have seen no data so I am only guessing that it adds several watts of friction.
A Chainglider must add some drag. Also a bit of weight, somewhere around 300 g from memory.
I was very sceptical when I first tried one, so I did 4 rides with and 4 rides without Chainglider over a 25 km circuit.
Contrary to my expectations I didn't notice any difference in my average times to complete the circuit, but I did notice a rubbing noise. I was testing a sub-optimal setup with 1/8" chain and relatively thick chainring and sprocket. The rubbing noise reduced sufficiently for me to no longer notice it after a few hundred kms.
So I concluded that the Chainglider drag was negligible. And I now have Chaingliders on all the family bikes except for aforementioned bike with vertical dropouts and the Brompton folding bikes.
Maybe I was lucky, some people have reported excessive drag, particularly with the thick Thorn chainrings.
-
My securely wrapped SJS order arrived today. The attached photos show that, as expected, the OEM2 axleplate only half engages with the support bolt (part 8552) although there's potential to cut a notch in the axleplate so a bolt through the mudguard mounting hole also provides some torque restraint.
However, my bigger, and unexpected headache, is that I expected the screw-on sprocket adaptor to screw onto the threads revealed after I had unscrewed (with great difficulty) the Gates sprocket. I was evidently wrong as part 8542S has a smaller diameter than those threads. Did I, in my joy of managing to unscrew the Gates sprocket, overlook the need to also unscrew that screw-on adaptor shuch needs a very big spanner to hold those very narrow flats? Has anyone previously beaten this path and can offer advice?
-
What a shame that OEM plate is so close! How does it line up with the cut out between the bolts? If that were a good fit a plate between them and a bolt for the OEM plate would spread the load.
I don't recognise that sprocket part on your hub, isn't your Mercury splined sprocket? Could you compare?
That copper finish looks good in the close ups, I haven't seen it other than in photos, I imagine it'll sparkle n the sunshine.
-
So, although the frame weighs less than the rear wheel with tire mounted
Do you know what the frame weighs?
I went into a fair bit of detail when I designed my own, ti is 45% lighter and 38% more elastic, lots of ways to build the required stiffness back in, but they all eat away at the weight difference. Spa is a good example to look at as they make several models in both materials that are identical sizes and geometry.
Any tensioner will add drag as a tighter chain increases chain friction and also jockey pulley friction, but the percentage of the total drag that is added by the tensioner is quite small. Drive train drag and tire friction will slow you down much more than an extra kg of weight because weight is not that critical unless you are a racer. If I was trying to build a really light bike that had a Rohloff, I would try to eliminate or minimize tensioner drag as much as possible.
Plenty of drivetrain efficiency testing had been done, at 150w a single speed without tensioner is around 98% and the most efficient gear on a derailleur is around 96%, so 2% difference, or about 4w. Assuming everything is clean, lubricated and in prime condition.
As with weight, if you start not counting the small increases/inefficiencies, they soon add up.
-
So, the Gates sprocket had an adapter that appears to have a big hex shape that is threaded onto the Rohloff?
My first thought was that a big vice should clamp onto the adapter just fine, but after thinking about it, the vice jaws could prevent you from putting a wrench (spanner) on the Rohloff tool.
I have a few other ideas, but those ideas could damage the Rohloff shell, so I am keeping my thoughts to myself. They are ideas I would try on my own but not recommend that others try.
-
What a shame that OEM plate is so close! How does it line up with the cut out between the bolts? If that were a good fit a plate between them and a bolt for the OEM plate would spread the load.
Thanks for this suggestion that I will investigate.
I've measured the flats on that screw-on adaptor as 46mm so this spanner https://www.ebay.co.uk/itm/233976816130 should fit and has a long handle. However, I presume that I need Rohloff tool 8508 again to hold the hub and, if this is also need for routine removal of the carrier, then I might as well get my own. Which is the tool for removing the spined carrier? Do I also need one of these https://www.sjscycles.co.uk/hub-spares/rohloff-lock-ring-8538 ?
-
Which is the tool for removing the spined carrier?
It's the same tool as for removing a threaded sprocket, you remove the carrier with the sprocket attached, the two parts are effectively the same as a threaded sprocket.
The part you link to is a lockring to be used on a different sort of carrier that doesn't have a circlip, most commonly found on belt drives, but can be used on chain sprockets as well, I've never actually seen one. One of these
https://www.sjscycles.co.uk/hub-spares/rohloff-splined-carrier-sl-slim-lock/
-
...
I've measured the flats on that screw-on adaptor as 46mm so this spanner https://www.ebay.co.uk/itm/233976816130 should fit and has a long handle. However, I presume that I need Rohloff tool 8508 again to hold the hub and, if this is also need for routine removal of the carrier, then I might as well get my own. Which is the tool for removing the spined carrier? Do I also need one of these https://www.sjscycles.co.uk/hub-spares/rohloff-lock-ring-8538 ?
With the corners cut off the way they are on the adapter, 12 point wrench might not get it done right and might make things worse. It looks like aluminum in the photo, the wrench might finish rounding off the corners.
I would look for either an adjustable wrench like I use or a six point wrench. The adjustable might work best, as the 6 point wrench might have enough bevel that it might not grip it well.
It is my understanding that the splined carriers that are recommended for chain drive use a circlip spring, but the splined carrier used for belt drive uses a threaded on piece to hold the sprocket on the carrier. I am guessing that lock nut you linked to is a spare for the belt sprocket carrier.
It is my understanding that the Rohloff tool for the threaded sprockets is the same as the one with the splined sprockets, you keep the sprocket on the carrier to use a chain wrench on it the same as you would with a threaded one.
ANd now I get a warning that Ph has already said much of what I just said.
-
It is my understanding that the splined carriers that are recommended for chain drive use a circlip spring, but the splined carrier used for belt drive uses a threaded on piece to hold the sprocket on the carrier. I am guessing that lock nut you linked to is a spare for the belt sprocket carrier.
From the Rohloff website
"Lock-Ring versions come with a lock-ring to secure Carbon Drive sprockets to them (can also be used with chain sprockets of 15 tooth and above)."
https://www.rohloff.de/en/products/speedhub/speedhub-accessories
Some people just prefer the idea of a lockring and a tool rather than learning the technique of fitting and removing a circlip.
-
...
Some people just prefer the idea of a lockring and a tool rather than learning the technique of fitting and removing a circlip.
Apparently the sprockets on the splined carrier with the split ring can loosen up and become noisy. The sprockets develop looseness on chain drive sprockets too, but apparently noise is not a factor on chain drive. I am only repeating what I have read here, I have not seen the lock ring type carrier.
I am guessing that my S&S coupler wrench would work on the lock ring, so if I had a choice I would probably choose that one for my chain drive Rohloff bike.
-
I've ordered my own Rohloff tool 8508 from SJS and I plan to use my pipe wrench on the screw-on adaptor as there can't be much of a second hand market for them.
I've also looked at the possibility of fitting the support bolt between the two bolt locations. It fits fairly snugly (see photo) and appears to be the best option to date. I'm thinking of improvising the bolt holder from two pieces of 4mm thick steel (probably stainless) flat bar. The dropouts are 3mm thick but there's about a 2mm gap between them and the axleplate so 4mm material reduces that gap. One piece of the steel will be on the outside of the dropouts but I'll make another piece that is carved to fit the valley between the bolt holes. The two can then be bonded with a thin layer Araldite (which IIRC used to be advertised as stronger than steel) before I drill the holes. A total of 8mm of steel should prevent any bending of the bolt. I've also ordered a box of assorted M5 cap screws to add to my collection. I need to sensure that they don't significantly protrude through the dropout and foul the axleplate.
-
Progress :) :) . SJS moved quickly on my order for Rohloff tool 8508 and with the help of first class post it arrived today. With the help of a pipe wrench and encouragement from a hammer the screw-on sprocket adaptor finally yielded. There was plenty of what looked like anti-seize on the threads but 3,000 miles of cycling had got it somewhat tight. So I now have a bike with both chainring and sprocket and a chain between them with the chain tensioner on a low tension setting. I've put the Rohloff support bolt in the upper mounting hole and plan to take a short ride tomorrow morning on some local rough degraded cycle paths to see how the bike feels. I'll refrain from tackling any steep hills until I've got an improved torque management setup.
-
The bike has been out for a couple of miles. The steering felt a bit different from the Mercury, perhaps because it has narrower AHS handlebars or there may be subtle differences in geometry. I've got wider AHS bars as the alternative but wanted to find out if the narrower bars (which I used on the bike which donated the Rohloff) felt as they are slightly easier to manoeuvre through obstacles and into buildings. The ride felt OK and the Brooks C17 saddle seemed comfortable (but 2 miles is far too short to reach a judgement). The photo shows the drivetrain setup.
The bike weighed 13.5kg in the configuration shown (except the saddlepack was removed). This seemed a lot so I removed the bags, water bottle and pump off the Mercury to get it to a comparable condition and came to 16.6kg. That weight, however, includes the forbidden kickstand, some mud and heavier grips on the handlebars so the true weight difference between the bikes appears to be around 2kg.
I'm already missing having a kickstand on the new bike and have ordered a Chinese copy of the Upstand https://www.amazon.co.uk/gp/product/B08T1S2P8L to see how I get on with it. However, I've got my eye on the non-folding Commuter Upstand https://upstandingbicycle.com/shop/the-commuter-upstand/ and have been in contact with the manufacturer who can send by international mail for $15. My interpretation of the current UK customs and tax rules is that the order would fall below value threshold attracting import charges at this end so I may order one once the Christmas period is over. The alternative is extend the proposed adaptor for the Rohloff support bolt to include mounting holes for a conventional kickstand - an adaptation of this https://www.sjscycles.co.uk/gear-spares/thorn-dropout-adaptor-with-kickstand-mount-18-mm. A proper kickstand, however, is running contrary to the weight reduction objective.
-
the true weight difference between the bikes appears to be around 2kg.
Be interesting, to me anyway, to take the wheels out of the equation and weigh again.
My friends steel Elan, with a full carbon fork (But not the one you have) and Shimano GRX groupset (2X11), whatever Spa do as a lightweight handbuilt wheels, road saddle, lightweight conti 32mm tyres, fancy mudguards... comes in well under 12kg, he was hoping it'd be under 11 and may get there yet.
Regardless of the weight, did it feel faster? I see you have some pretty chunky tyres, I know it's still a work in process, but for the usage you've described that's probably where the biggest advantage lies.
-
I took the frontwheel off and it weighed 1.67kg complete with a 37mm Marathon Mondial Tour tyre (which Schwalbe says weighs 0.57kg) and inner tube. Those tyres were on the wheels already and will stay there until the roads become less mucky when the tyres will be replaced by 40-622 G-One Speed (weight 0.465kg). The rims are tubeless ready American Classic Hurricane (approx 2014 vintage although new along with the rest of the bike when I bought it in 2019 ago). If I can get them to seat on the rims then that will save about 0.3kg on the weight and improve the ride. A hollow axle crankset might also save a little weight as would narrower tyres, ditching the mudguards, Chainglider (and could then fit an aluminium chainring), fitting simple handlebars and using a lightweight saddle. I didn't have a weight target but was wanting less heavy than the Mercury and less temptation to add more baggage than necessary. A Rohloff hub will never compete on weight with a lightweight groupset.
I went out today for what I expected to be 4 miles but ended up travelling 12 miles on a route which needed nothing lower than 8th gear. I had adjusted the handlebars after yesterday's ride and they felt much better and, while the bars appeared, when looking at the bike, to be higher than I intended this seems to be an illusion as my body position felt fine. On the first part of the trip the bike felt fast but then the final part was into the wind which was like cycling through treacle. I'll need a reasonably calm day and a trip around a longer (~25 mile) circuit before I can get a proper feel for whether the bike is faster than the Mercury (which I've just switched from G-One Speed tubeless to Panaracer GravelKing SK with tubes for some extra winter grip and noticed that the bike felt slower). Also of great interest to me is how well the bike felt on rough bits of road and in this respect it was OK.
One little annoyance is that I'm getting some rubbing noise from the Open Chainglider. It seems to be diminishing with usage so I hope it will become as quiet as the Chainglider on the Mercury. I'm now waiting for some bits of stainless steel for the Rohloff torque anchor and once that is done then I can look for a gap in the weather for a trip around a longer circuit.
-
You could get another bike that’s really heavy and ride it for ten minutes , then go back to the Mercury
Tricking your nervous system or something like that ☺️ It will make the Mercury feel super light in comparison
A bit like how bodybuilders do with lifting weights
I thinking the lighter and weaker we go with things , the benefit might be short lived and wear off after a while unless we also have something that is also stretching us in the opposite direction
I find this with playing guitar and setting it up to play with lighter strings and lower action . The initial results can feel amazing but our bodies seem to get used to it too quick. Our hands get weaker coz there’s less tension
I was just looking at Thorns weight recommendation for their frames today (Mercury included ) it got me thinking . Although the Mercury is light , it can still carry a fair bit of weight . So maybe it’s not that light 🤔
-
You could get another bike that’s really heavy and ride it for ten minutes , then go back to the Mercury
I didn't think the Mercury was heavy until I saw some of the other bikes on a group bike ride. Part of the problem was that having a bike designed to carry a load encouraged me to carry more than necessary.
My Mk. 1 torque anchor (3 holes in a 20mm x 35mm piece of 4mm thick steel) wasn't to my satisfaction (using a hand held drill isn't very accurate) so I'm I'm now planning a Mk. 2. However, I wonder if I'm over-engineering a solution since one of the Rohloff options uses an M5 bolt https://www.sjscycles.co.uk/hub-spares/rohloff-oem2-adapter-for-m5-fender-luggage-rack-bolt-8552 and a quick calculation which might be wrong) suggests that there isn't a very big factor of safety against that bolt shearing off under Rohloff's worst loading condition. As one of my mounting holes is 10% more than the recommended distance from the axle then I've effectively got a 10% higher FoS. If only the fingers on the OEM2 axleplate were a couple of mm longer then I'd be happy to go that route as the permanent solution.
While waiting for the permanent fix I've taken the bike out on a couple more rides which didn't require going lower than 6th gear. After the first ride with the steering not feeling completely OK I've changed the handlebars to the longer Ergotec AHS bars (SJS are selling the silver version at a fair price https://www.sjscycles.co.uk/handlebars/510-humpert-ahs-basic-sport-handlebars-cw-comfort-barends-254mm-clamp-silver) and now the steering feels just the same as the Mercury - probably a matter of what I've got used to. Today's ride was 27 miles and no slower than I would expect with the Mercury but the wind wasn't favourable. The Chainglider has got quieter but the second half of the noise had another slight rubbing noise from, I think, some muck inside the rear mudguard. The damp weather cause caused filthy roads not helped by large vehicles spreading muck from the edges towards the middle. Some heavy rain would temporarily get the roads clean.
I've also noticed that the Rohloff hub seems to have become quieter in low range than when on its previous bike. I'm wondering whether the larger diameter aluminium tubes on that bike made an effective noise amplifier.
-
I got fed up with waiting for a piece of 1mm thick steel which would form part of the planned Mk 2 support bolt carrier and have implemented Mk 3 which involved cutting a notch in the axleplate so that it's restrained from rotating by 5mm bolts in both the mudguard / rack mounting holes. I also put a piece of 1mm thick aluminium on the end of the smaller finger of the axle plate so that it's a fairly tight fit on the Rohloff support nut (part 8552) so there's no movement when changing the torque direction (above / below 11th gear). The notch in the axleplate rests against the head (8mm dia) of a 5mm capscrew threaded from inside to outside of the dropout. The photos should illustrate how it's put together.
The main disadvantage compared with the planned Mk 2 restraint (which would place the 6mm support bolt in the valley between the two mounting holes) is that the Rohloff cables are hanging below the chainstay so I'll probably improvise a rigid support. It's also slightly more fiddly getting the wheel into the drop-outs.
The next task is to take the bike up my worst local hill (approx 1 in 6) which I normally crawl up in 3rd gear. Perhaps the worst test I can do is try accelerating from hill start in 1st or 2nd gear to add a bit more load. I don't know of an even steeper hill in my area.
-
The less heavy bike project is effectively complete. It's clocked up over 100 miles including a couple of trips up my worst local hill without any signs of distress. Since my last post I've changed the mudguards (SKS Bluemels from Wiggle's outlet on ebay https://www.ebay.co.uk/itm/154739257339) although there was a bit of fun routing the front nearside stays around the disc brake rotor and I tidied up the cables including an improvised holder for the Rohloff cables below the chainstay. I'm planning to make minor adjustments to the handlebar position in the quest to find the best balance between wind drag and comfort.
It's 2.3kg lighter than the Mercury in similar configuration. I could reduce the weight further by sacrificing features I want such as a comfortable saddle, the AHS handlebars, flat pedals with grip, some chain protection and the mudguards (I bought these cut-down guards for the summer https://www.amazon.co.uk/gp/product/B004R4I6XI). Hollow cranks might save a few grammes. Whether this bike is faster remains to be seen as the time around my various circuits depends on a range of factors, such as weather (particularly wind speed and direction) and how I'm feeling with the bike itself being a lesser factor. It's as comfortable as the Mercury on a range of surfaces in spite of narrower tyres although I think the Mercury's 50mm tyres are slightly better on gravel.
Thanks to all for the helpful comments that have encouraged me to get to the end of this project which has resulted in a good Rohloff-equipped bike for somewhat less cost than a new one. Hindsight is a wonderful thing - I should have thought of this before I bought the Mercury! The next unknown is whether the Mercury is redundant and needs to be listed in the for sale forum.
-
Looking good, the cable run isn't as messy as I thought it would be. I have one of those blue Brooks, after a lifetime of saying saddles should be black, though at least mine is on a blue bike ;)
Your post does have me scratching my head, as has much of this thread. Where does that 2.3kg come from? I know about 600g will be the fork, what about the rest? If there's any difference in frame weight it'll be minor and I'd have thought in favour of the Mercury.
And now you're contemplating selling the Mercury :o :o :o
Your bikes and your choices of course, but I still think, as I said at the start of this thread, trying your Mercury in a light build would have given you a practical benchmark.
-
Unfortunately, Wiggle's sale of C17 saddles at £59.99 didn't include the copper coloured version.
I may have over-stated the weight difference as I should have given both bikes a wash before the weighing session and the Mercury has has more opportunity to collect dirt, particularly on the inside of the mudguards. Both weights were without the saddlepacks.
In the ideal world I would dismantle each bike into the constituent parts and weigh them individually but that's not on my to-do list. :o While the Mercury's 983 steel is stronger than the 725 used in the Elan frame, the latter is one size smaller (52 vs 55L) and may be designed for a lighter loading (Spa doesn't give numbers) but the weight comparisons earlier in this thread were between the Elan frame and the Thorn Audax frame, not the Mercury frame which is rated for higher loading than the Audax. BTW, I've accidentally discovered how thin the metal is in Elan's top tube: Tap it gently with a bit of metal and it rings like a bell (there's nothing attached to this tube to dampen the sound).
My Mercury's forks are the heaviest option, with disc brake capability and chunky axle which means the maximum weight difference between those and the full carbon (including steerer) forks on the Elan and this is probably the biggest component of the weight difference. Otherwise it's the sum of small differences. The rims on the Elan are narrower (17mm internal width) and look to be lighter than the rims on the Mercury. The 48-584 GravelKing SKs are about 40g each heavier than the 37-622 Marathon Mondials on the Elan plus there will be a proportional difference in the weight of the tubes and mudguards.The Mercury's EBB must add a bit of weight (which might be offset by the chain tensioner on the Elan), both bikes have square taper bottom brackets, fairly chunky cranks and the same pedals (MKS MT-FT). The Mercury has a full ChainGlider while the Elan as the open ChainGlider. Both have the same handlebars although the Knog Deluxe bell I've put on the Elan will be lighter than the traditional bell on the Mercury. Both bikes have Wiggle's carbon seatpost. There's a small difference between the advertised weights of the C17 (464g) and Aravis Ti (425g) saddles which is in favour of the Mercury.
I agree that I could have had a Mercury in a lighter specification but, if I didn't want to forego a front disc brake and minimum 40mm tyres with mudguards or a good saddle then I don't see much option for weight reduction. In addition, as I think I noted at the start, this was also an exercise in recycling as much as possible from a too-small aluminium-framed bike to build something more attractive that would be, I hoped, be lighter than the Mercury. One part that I didn't yet recycle was the Sram X5 hollow axle cranks and bottom bracket and that was because the cranks are 175mm. However, I'm tempted to try as that BB is 68mm and should fit the Elan frame complete with the right chainline. Sensibly the hollow axle should mean less weight.
Seeking a new home for the Mercury was always a background thought as I am trying to reduce my bicycle collection. I've nothing against the Mercury, as 7,800 miles in 17 months should testify but my group bike rides have revealed that it's over-engineered for the touring I've done (and hope to do more of) which isn't real touring in that there's a van to carry the baggage. There's probably someone out there in greater need of the Mercury. Should I decide to try some credit card touring then I can put a rack on the Elan. First I must clock up some more miles on the new bike.
-
Oh well, your choices. There's no reason why you should prefer the Mercury to the Elan, I wouldn't know if I would, so I certainly wouldn't know for someone else. The difference is I'd want to base that on experience rather than theory, I'd ride the Mercury with the same wheels and fork to make a genuine comparison.
Just on the factual stuff:
In the ideal world I would dismantle each bike into the constituent parts and weigh them individually but that's not on my to-do list. :o While the Mercury's 983 steel is stronger than the 725 used in the Elan frame, the latter is one size smaller (52 vs 55L) and may be designed for a lighter loading (Spa doesn't give numbers) but the weight comparisons earlier in this thread were between the Elan frame and the Thorn Audax frame, not the Mercury frame which is rated for higher loading than the Audax. BTW, I've accidentally discovered how thin the metal is in Elan's top tube: Tap it gently with a bit of metal and it rings like a bell (there's nothing attached to this tube to dampen the sound).
The Merc is Reynolds 853, I'm sure you knew that.
I think the Elan, like all Spa steel bikes, only uses 725 for the main three tubes, the minimum to be able to use a Reynolds sticker. The stays are generic steel, nothing wrong with that, though it's probably not heat treated and therefore needs to be a bit thicker. The lightest gauge of 725 main tubes is 0.8/0.5/0.8, that's also the most common 853 gauge and I expect what's used on the Mercury, though 853 is also available 0.7/0.4/0.7.
I'm not telling anyone what they should do, but if you choose the Elan over the Mercury on the basis that it's a significantly lighter bike that isn't an evidence based decision.
-
The Merc is Reynolds 853, I'm sure you knew that.
I think the Elan, like all Spa steel bikes, only uses 725 for the main three tubes, the minimum to be able to use a Reynolds sticker.
I'm not telling anyone what they should do, but if you choose the Elan over the Mercury on the basis that it's a significantly lighter bike that isn't an evidence based decision.
Yes, there was a keyboard mulfunction regarding the steel type used in the Mercury.
I'm not disputing that I could have rebuilt the Mercury to be less heavy but I was trying to use the good parts off a bike that was too small to build something usable and, I hoped, would be less heavy than the Mercury without a massive financial outlay. For the price of the Mercury frame I could have got the Elan Ti frame which would definitely win the weight comparison. Anyway, I've now got two good bikes and a 49cm aluminium frame on which I place no value.
-
This thread started to make a lot more sense to me when I looked up the disc front fork (https://www.sjscycles.co.uk/forks/48-offset-a-700c-650b-26-inch-thorn-mk3-steel-disc-fork-red-imron/?geoc=AU) Thorn supplies for the Mercury and discovered it weighed 1.5kg.
That's 450g more than my ST fork and 650g more than the Reynolds 853 fork that Thorn also offers for the Mk 3 Mercury.
There's not only the added mass. Thorn says the ride suffers, rating the fork at 4.5 for comfort against the 853 fork at 10. The ST fork is rated at 8.
It is all very well to say that some comfort is returned by a fat 650b tyre but it comes back in another way. The perception of liveliness from the frame likely suffers.
Thorn used to offer a carbon fork with disc brake for the Mercury. Andy B reports in the megabrochure that he switched his personal lightweight Mercury from the disc brake carbon fork to the rim brake 853 fork and preferred the latter (p61).
If you have to have a disc front brake then I can see why the built up Spa bike could save you nearly a kilogram in the fork alone. FYI on the Mercury frame, I can confirm that Thorn quotes 0.8/0.5/0.8 for the main tube thicknesses.
Anyway good luck John with the experiment - I look forward to further comparisons as you gain experience with the Elan. I am tempted to say that if I had been on a similar quest I would simply have gone for an 853 fork, lighter rims and the lightest tyres I could find - Rene Herse Babyshoe Pass 650bx42mm are rated at 373g in the extralight casing. But then I like the rim front, disc rear brake set up I have on my Mercury and I don't assign a lot of value to braking performance.
-
My Mercury was pre-built (it's the one on page 2 of the megabrochure) but even if it was built to order I'd still be wanting disc brakes all round as I place a lot of value on being able to slow down or stop quickly and have had variable past experiences with rim brakes (that said, my last rim-braked bike had good stopping ability but I was worried about the speed at which the rims were wearing).
I've got a pair of 38mm Panaracer GravelKing SK tyres on the way to fit on the Elan and will be interested to see how they feel. I've used the 48mm version on the Mercury as my winter tyre (1500 miles on the Mercury last winter before being swapped). Despite being knobbly they run very well on normal road surfaces (they hum on a smooth surface) and have the extra grip for either filthy road surfaces for gravel paths. I think the Marathon Mondials currently on the Elan prioritise durability (as fits the name) and give a fairly firm ride. While the tread is deep there's a lot of smooth rubber between the grooves which might be why I had a loss of traction on a piece of very smooth damp tarmac when going uphill a couple of days ago which left me unbalanced. I've been up that hill innumerable times without previous problems but maybe not with those tyres at that fairly cool temperature (rubber is less flexible at lower temperatures as I noticed when I got on the C17 saddle - it improved once warmed up).
I'm also waiting to see if the Elan ticks enough boxes that the Mercury is redundant.
-
The GravelKing SK tyres arrived yesterday and fitted tubeless on the rims with minimal hassle (unlike the rims on my Mercury). I went out for a ride today and the bike was faster. Whether that was due to the tyres, less wind or my legs feeling energetic (or a combination) isn't clear.
-
My Ribble Adventure is 5kg lighter than my Nomad mk2 & I only really notice the difference when having to lift it over stupidly designed gates on cycles paths .
-
I agree that the weight is most noticeable when having to lift the bike. I had to carry the Mercury up /down stairs in some hotels on my LEJOG.
The nearly-new bike has now travelled over 250 miles, 43 of which were on Boxing Day when the weather was good for the time of year. I surprised myself by taking only 5 minutes more than my best time in summer. Something I've noticed is that the steering is more jittery than the Mercury which I assume is primarily due to the Mercury's heavier front wheel and tyre provides greater gyroscopic stability. However, I don't see that as a good reason to keep the Mercury.
-
However, I don't see that as a good reason to keep the Mercury.
Well done for finding what you set out looking for, I've still no idea why you think you needed a change of frame to achieve it, your strong rejection of the suggestion to try that build with the Mercury was based on you wanting to keep it as it is ;)
It doesn't surprise me that having built two bikes with similar geometry and tubesets you now question the need for them both. I'd say it's almost inevitable, it's a point I've made several times over the years and a lesson learnt from my own mistakes.
Which is the better bike with a light fork and 700c wheels? There's only one way to find out and I'm incredulous that you don't have the curiosity to do so.
But... your bike, I hope you have many happy miles on it.
-
My Ribble Adventure is 5kg lighter than my Nomad mk2 & I only really notice the difference when having to lift it over stupidly designed gates on cycles paths .
I'm surprised by that, they seem very different frames.
There's about 4 kg between my Surly Ogre (Rohloff) and my Thorn Mercury, a fair bit of that difference is the wheels and frameset. It's not the same riding experience, the Surly goes wherever you point it, it's a very relaxing ride, but on a reasonable road it isn't very engaging. The Mercury is far more responsive, it reacts quicker to any change while still predictable enough to be considered a tourer.
Over the course of a full days ride it won't make much difference to average speed, though pulling away from a junction or powering up a short hill and it's chalk and cheese.
-
Well done for finding what you set out looking for, I've still no idea why you think you needed a change of frame to achieve it, your strong rejection of the suggestion to try that build with the Mercury was based on you wanting to keep it as it is ;)
One objective of the project was to re-use the good parts from another bike which was a little small for me, had the ride quality appropriate for the aluminium frame and had inadequate clearance between toes and front mudguard (due to, I assume, a combination of 49cm frame and 175mm cranks). Knowing the limitations of that bike meant my conscience wouldn't let me try to sell it on. The option of modifying the Mercury would have left the unwanted bike taking up space.
Hindsight indicates that I should have embarked on the build-your-own project 18 months ago instead of buying the ready-made Mercury but my knowledge and confidence in such matters has improved significantly during the past 18 months. Anyway, the new bike is continuing to show a good turn of speed but I'm motivated to pedal harder as I'm trying to confirm that it's faster / less effort than the Mercury.
It's looking likely that the red Mercury will end up featuring in the for sale section.
-
The new bike has been running sweetly but I've had problems with the Wiggle carbon seatpost slipping down. I've therefore raided the piggy bank and bought a titanium seatpost https://www.spacycles.co.uk/m9b0s84p3707/ORA-Titanium-Seatpost-27-2mm . This had its first trip today and proved effective at filtering out vibrations from indifferent road surfaces and it didn't slip down. It's also a few grams lighter than the carbon seatpost.
-
...I've had problems with the Wiggle carbon seatpost slipping down...
Seatposts can slip downward for a number or reasons -- mismatch in size, inadequate torque, or over-greasing.
Carbon posts don't get along well with grease, which can cause slippage. Using a carbon assembly paste will often fix the problem and keep a carbon post secure.
By any chance, did you use carbon assembly paste on yours? If so, then I'd suspect one of the other causes.
Best,
Dan.
-
I have no experience with carbon anything. That said, I had an aluminum seatpost that would slip, slipped on different bikes so I think it was slightly undersize.
It was painted black. Two or three additional layers of paint from a spray can made it a bit bigger, stopped slipping. Let the paint harden for at least a few weeks, so it would be fully hardened before I used it.
-
Carbon posts don't get along well with grease, which can cause slippage. Using a carbon assembly paste will often fix the problem and keep a carbon post secure. By any chance, did you use carbon assembly paste on yours? If so, then I'd suspect one of the other causes.
I removed all traces of oil and grease. I tried carbon assembly paste which made things worse as the jelly appeared to act as a lubricant.
I think the underlying problem was the clamping arrangement. I didn't want the slot at the top of the seat tube to cut into the carbon post so I rotated the clamp (bolt at the front) to try to spread the clamping load but the result was that it couldn't get tight enough.
I have no experience with carbon anything. That said, I had an aluminum seatpost that would slip, slipped on different bikes so I think it was slightly undersize.
It was painted black. Two or three additional layers of paint from a spray can made it a bit bigger, stopped slipping. Let the paint harden for at least a few weeks, so it would be fully hardened before I used it.
I also had a slipping Thorn seatpost on my Mercury and my calipers suggest that it was slightly undersize. In this case the fix was 6 layers of aluminium cooking foil between the shim and the seat tube.
Overall, I look on the carbon seatpost as a useful experiment which was successful in improving comfort and reducing road buzz. However, there's the lingering doubt that it might break at the wrong moment particularly on a longer ride with a loaded saddle bag adding to the bending force. The titanium post removes these worries without providing the harsher ride of an aluminium post. With hindsight (a wonderful thing) I should have tried the experiment some time ago as it lets me run the tyres a bit harder.
-
I think the underlying problem was the clamping arrangement. I didn't want the slot at the top of the seat tube to cut into the carbon post so I rotated the clamp (bolt at the front) to try to spread the clamping load but the result was that it couldn't get tight enough.
Yes that would do it, without the two gaps lining up the effectiveness will be reduced.
Those Ti posts look good, though I've heard people having issues with the saddle clamp, I'd be tempted, except prefer more layback.
-
Yes that would do it, without the two gaps lining up the effectiveness will be reduced.
Those Ti posts look good, though I've heard people having issues with the saddle clamp, I'd be tempted, except prefer more layback.
I reckon its actually 25mm offset as listed at https://www.oraeng-tw.com/sp002-bike-seatpost.html and seatposts with even more offset aren't easy to find. 20 to 25mm suited me as the bike was set up for the wiggle carbon seatpost which is 22mm offset.
At the moment my biggest complaint about the saddle clamp is that access to the main both is impeded by the edge of the saddle. There's also what is marked as a security screw on the back of the clamp. In the absence of any additional guidance I assume this should be tightened when the saddle is in place and adjusted.
PS: Having checked the saddle position today because I felt on yesterday's ride that it needed moving forwards I discovered that it had slipped backwards so it isn't gripping the rails as tightly as needed. I've now given the problem a little thought and will get the seatpost and saddle off the bike for a closer examination. My current thinking is a layer or two of car touch-up primer pain on the inside of the jaws that grip the saddle rails or, if there's a bigger gap to be filled, a thin layer of epoxy resin glue. It's a fine balance as too much filling will impede the teeth on the vertical ange adjuster from engaging.
-
I think I've finally fixed the saddle slipping backwards problem. Paint didn't do any good so I applied a thin layer of slow setting Araldite to the inside faces of the rail clamps and left it overnight on a radiator to harden. After that I had to file a lot off until the clamps were a snug fit on the rails. However, that wasn't enough by itself to stop the saddle moving back but I had noticed that while I had everything tight before the ride that the saddle rotated backwards slightly once when I went over a substantial bump despite my efforts to ensure that everything was tight. This indicated that the teeth controlling the rotation weren't properly engaged at the start (and I couldn't have the saddle in my preferred position of horizontal) but also meant that once those teeth were engaged then the grip on the rails was reduced until the bolt was retightened. After resetting the saddle distance from the bars, making it horizontal and putting a little gease on the clamp bolt (to help get it tight) I took a large Allen key of the appropriate size on the next ride. Then, once I felt the saddle rotate slightly, I stopped and retightened the bolt. There has then been no further saddle movement on that ride (yesterday) or today.
The other ongoing experiment has been the handlebar height on the basis that if I can get my body a bit lower then there will be less cursing of the headwinds. Over several weeks I've been intermittently dropping the bars in 5mm increments starting at a height similar to what I had on the Mercury to find the limit where I felt uncomfortable. Yesterday I took the drastic measure of flipping the 7 degree 110mm stem from up to down but moving it to the top of the steerer which resulted in a 20mm drop from the previous bar position. One ride revealed that there was too much weight on my arms so the stem has been flipped again and moved down the steerer. A zero degree stem higher on the steerer would likely be the optimum solution but fixed zero degree stems aren't common and I don't want the extra weight of an adjustable stem.
-
It's a year since I started this and an update is appropriate. The copper-coloured Elan 725 provided 6 months of trouble-free cycling including Lowestoft - St Davids (supported by a van carrying the baggage). There was only a dozen of us and I was at the back on the flat roads of eastern England but near the front when we reached the Welsh hills and the lower gearing than most derailleur bikes came useful.
However, I then started thinking about how I could further improve on what I had built. Further reading made me realise that a titanium frame not only provides a further weight reduction but also further improves comfort as it's less stiff than steel. As I'm under 65kg and normally have no more than 5kg of baggage I don't want a strong frame but something that helps absorb the rough bits of road. That's where I went wrong with choosing the Mercury - it's designed for at least 20kg more than I'm likely to need (the Mercury is still waiting to be rehomed).
I was very happy with the geometry of the 52cm steel Elan frame so I arranged to visit Harrogate while on the annual car holiday and inspected the titanium Elan frame and satisfied myself that there would be no serious problems with fitting the Rohloff hub. After the holiday the Ti frame was delivered and I spent a day moving all the components to the new frame. Modifying the Rohloff OEM2 axleplate to fit the Elan Ti frame was easier than with the steel frame. It just required deepening the valley between the two fingers as the axle - rack bolt hole spacing was 36mm instead of Rohloff's specified 40mm and putting Rohloff support bolt 8560 through the rack bolt hole. Perhaps it was wishful thinking but the rough bits of road on one of my circuits immediately felt smoother. Had I appreciated this advantage of the titanium frames then I would have gone that route instead of steel a year ago.
After a few hundred miles on this bike I started to wonder what else I could improve. One problem was that a Carradice Super C saddle pack was bouncing on the rear mudguard and I used a strap through the saddle rails to lift it which reduced the available capacity. After more miles of pedalling and thinking I realised that smaller wheels would not only help with this problem but also address another problem which was that with the optimum saddle-pedal spacing I could only put a few toes on the ground when stopped. My Mercury has 584 rims and I never had problems caused by the height of the bottom bracket. So I commissioned Spa Cycles to build me a new 584 front wheel and rebuild the Rohloff hub into a 584 rim. (I chose Spa for this work as they stocked Kinlin TL-21 tubeless rims in the 584 size). As noted elsewhere, I fitted the Rohloff flange support rings before the hub went for the wheel build.
One photo show the bike in its current condition with a Carradice Maxi saddlepack (the Super C saddlepack is a size bigger although the nominal capacities are the same) and I've just fitted full mudguards instead of clip-ons now the weather has turned wetter. The tyres are Schwalbe G-One Allround (35mm on the front and 40mm on the rear) which were very easy to mount tubeless on the Kinlin TL-21 rims. The other photo is a detail of the rear hub showing the Rohloff axleplate.
-
That's where I went wrong with choosing the Mercury - it's designed for at least 20kg more than I'm likely to need (the Mercury is still waiting to be rehomed).
Bike looks great, but I have no idea what you base the above statement on? Spa suggest the Elan is suitable for the same sort of light camping load that Thorn suggest is appropriate for the Mercury. Both offer forks suitable for front panniers to increase that.
I note there's no numbers on your update, a little surprising considering the title of this thread!
I'm going to guess the frame is 800 - 900g lighter than the Mercury and the fork (Which you could have changed anyway) is another 700g. I'm also surprised by the change back in wheel size, as you were looking for something faster it seems like a backwards step.
-
John your priorities are very different from mine and it's clear you are on a journey with bike config that is keeping you engaged and riding. That's the great thing. And I suspect you're doing many more miles than I am at the moment. (Poor weather and the excitement of a new to me motorcycle having confined my Merc to the garage past couple of weeks).
I've no idea whether I can reach the ground from the saddle of my Mercury because I've never had reason to try. Yet for you, the desire to do so more comfortably motivates a wheel rebuild.
Your bike looks incredibly good but there's no way I'd be trading my Mercury for an equivalent. But then I don't need a disc fork, and if I did I might be much less satisfied with the Merc. It's fantastic that you are working your way towards what you want, and thanks for taking us along on the ride with you.
-
Nice looking bike.
I am pretty happy with my titanium bike, but mine was built for loaded touring so I am sure it is a stiffer frame than yours. And my wheels were built for the extra weight of four panniers. Mine is a 3X8 drive train, half step plus granny. Not Rohloff.
-
Bike looks great, but I have no idea what you base the above statement on? Spa suggest the Elan is suitable for the same sort of light camping load that Thorn suggest is appropriate for the Mercury. Both offer forks suitable for front panniers to increase that.
I note there's no numbers on your update, a little surprising considering the title of this thread!
I'm going to guess the frame is 800 - 900g lighter than the Mercury and the fork (Which you could have changed anyway) is another 700g. I'm also surprised by the change back in wheel size, as you were looking for something faster it seems like a backwards step.
I'll try to address these valid questions.
1. Thorrn's Mercury brochure http://www.sjscycles.com/thornpdf/BUILD8MERCURY650bROHLOFF.pdf states the rider + baggage weight to not exceed 120kg with my Mercury's build (disc fork) or 110kg with the Thorm 853 fork. I'm unlikely to ever exceed 80kg for rider + baggage. Spa give no indication of load limits and just describe the Elan as "It's a light tourer, or you can fit big tyres and hit the trails, or light wheels and join the chaingang" https://www.spacycles.co.uk/m11b0s143p3698/SPA-CYCLES-Titanium-Elan-Mk1-Frameset. The description includes "Paying attention to tube profiles as well as sizes means its stiff enough to be quick, but not so stiff to be uncomfortable". The same wording is used for both the 725 steel and titanium frames. I read through the comments of the frame designer (Colin 531) on the Cycling UK forum https://forum.cyclinguk.org/index.php to help understand both the difference in characteristics between steel and titanium frames and the constraints on frame design.
2. Thorn states that the Mercury uses Renolds 853 steel for the frames and 725 steel for the stays. The frame of the Elan 725 is 725 steel but it's not clear what steel is used for the stays. 853 steel is 11% stronger than 725 steel https://www.reynoldstechnology.biz/wp-content/uploads/2015/08/rtl_steel_alloys_extract.pdf although both tube diameter and wall thickness will influence frame strength. I therefore assume, without supporting data, that the maximum comfortable load (rider + baggage) capacity of the steel Elan is around 100kg and the Elan Ti is a bit less. I don't want more stiffness than needed for my loading conditions as additional stiffness results in a harsher ride. In reality, an Audax frame would probably have the right stiffness and I investigated the Thorm Audax but crossed it off due to the tyre width limitation.
3. I've done some weighing: My Elan Ti with full carbon forks weighs 12.9kg without the bags shown in the photo and with G-One Allround tyres (35mm on from, 40mm on rear) the Ergotec AHS handlebars and rubber grips, an Aravis saddle, the open Chainglider, bottle cages and small lights. The Mercury weighs 14.1kg in the original condition (Thorn handlebars and Thorn saddle) except it's currently shod with 48mm GravelKing SK tyres with tubes instead of the original 50mm Schwalbe G-One Speed tyres with tubeless sealant. With the same equipment on both bikes the difference in weight would be between 1.5kg and 2kg.
4. I would see the choice of tyre to be a bigger factor in rolling resistance than the difference between 650b and 700c. I fitted the G-One Allrounds on the 650b for two reasons: (a) they are the same sizes as the G-One Speed tyres I had been using with 700c wheels and (b) we are into autumn and the likelihood of mucky roads. I've got a pair of 30mm 650b G-One Speed tyres to try in the spring when the winter muck has cleared but even if they are faster I may conclude they don't justify the likely reduction in ride quality. From my ride logs I estimate that the Elan Ti with the 700 wheels was 0.5 to 1 mph faster than the Mercury. Given that it's reckoned that weight doesn't matter (except when going uphill) then one key factor in that increase is the less harsh ride.
In case you're wondering what I'll do with the Elan 725 frame, there's a winter project to build a bike with a 2 x 10 derailleur drivetrain
and see how it compares. I might decide it's a better option for the summer months than the Rohloff.
-
I'll try to address these valid questions.
Thanks for taking the trouble to do so.
You seem to have built a bike that suits you better than your Mercury did, nothing I or anyone else says should in any way take anything away from that. It's just chat! I swap bikes around fairly frequently, so it would be both stupid and hypocritical of me to to suggest I know what suits anyone else when I can't always work it out for myself!!
However, where we stray from opinion to detail, I am inclined to comment...
I therefore assume, without supporting data, that the maximum comfortable load (rider + baggage) capacity of the steel Elan is around 100kg and the Elan Ti is a bit less.
There's lots of evidence this assumption is wrong, frame weight, tube diameter and gauge, construction... Leaving that aside, Spa would simply be irresponsible to advertise a bike as an All-Rounder with touring and off-road capability, if it had a designed weight limit that many of their customers will exceed. The large differences in the Thorn brochure between configurations are sometimes confusing, though it doesn't surprise me the difference a fork will make, it is the weakest link.
I've done some weighing: My Elan Ti with full carbon forks weighs 12.9kg
That's a reasonable weight for a light touring bike, my Mercury is 1.1kg heavier, though it's a few sizes larger and that includes a rack. The last build of my Hewitt Cheviot was 12.5kg, though that wasn't the most practical build. I know someone with a Spa Ti Tourer that weighs under 13kg. These are the sort of weight differences I've been suggesting throughout this thread. There's lots of reasons you might prefer the Elan, there is something different about Ti and the lighter the rider the more noticeable that seems to be. I'm still of the opinion that these sorts of weight differences are not a significant factor in themselves.
I would see the choice of tyre to be a bigger factor in rolling resistance than the difference between 650b and 700c.
Yes, tyre choice is without a doubt the biggest factor. However, all other things being equal, bigger wheels roll faster, while smaller wheels accelerate quicker. You must notice this with your Birdy, I do with my Airnimal, the difference between 700c and 650b obviously won't be as marked but it's always there.
In case you're wondering what I'll do with the Elan 725 frame, there's a winter project to build a bike with a 2 x 10 derailleur drivetrain
and see how it compares. I might decide it's a better option for the summer months than the Rohloff.
That would be interesting, making the comparison between gearing on the same bike. I have a friend with the same bike who, at some expense, got his down to less than 10kg (Without guards).
-
However, all other things being equal, bigger wheels roll faster, while smaller wheels accelerate quicker. You must notice this with your Birdy, I do with my Airnimal, the difference between 700c and 650b obviously won't be as marked but it's always there.
I reckon that the Birdy is 10% slower than the bigger bikes. Some of that is due to the 18" wheels but I wonder if other factors such as the dynamo are adding to the drag. In theory the dynamo drag shouldn't be significant but 5W is 5% of an average rider power of 100W.
That would be interesting, making the comparison between gearing on the same bike. I have a friend with the same bike who, at some expense, got his down to less than 10kg (Without guards).
I won't be looking to achieve the absolute minimum weight (my choice of handlebars won't help in that respect) but, by my choice of gearing (probably 42/24 + 11 - 36) can provide a gearing range that closely matches my current Rohloff build. A few years back I had a Dawes Super Galaxy and the 3 x 9 gearing suffered two major limitations: Too much gear overlap and overall gearing too high for me.
There's a bit of me that has the urge to try fitting a Rohloff on a carbon fibre frame. However, the rest of me questions if that is a good idea as the rear triangle won't have been designed to handle the Rohloff's torque (with the worst loading being in the opposite direction to the force applied for a disc brake). However, should I decide that a 2 x 10 derailleur bike deserves a place in my garage then I may get tempted to investigate the carbon fibre frame option. It won't provide a big weight reduction compared to titanium but every little bit helps offset the effects of the rider getting older. I'm becoming a belated bike fiddle but it's fun applying the accumulated experience to the creation of something slightly better suited for my needs.
-
However, all other things being equal, bigger wheels roll faster, while smaller wheels accelerate quicker. You must notice this with your Birdy, I do with my Airnimal, the difference between 700c and 650b obviously won't be as marked but it's always there.
On good road surfaces, my own experience with 16" and 20" wheel Moultons suggests that wheel size isn't all that important when combined with a good suspension system.
My old 16" Moulton Stowaway wasn't much slower than my 700C lightweight on a long commute after I modified it to take 7-speed derailleur gears and drop handlebars. And some of the difference comes from using inefficient small sprockets, 11T smallest on the Moulton compared to 14T smallest on the 700C bike. When Moulton bikes were first introduced, they managed to break some speed records. I suppose the lower aerodynamic drag of small wheels offsets the lower rolling efficiency at high speeds.
The 16" wheel Bromptons I have now are noticeably slower, probably because of the more upright riding position and lack of front suspension.
On very bad surfaces, bigger wheels are much more efficient than small ones, that's why tractors have such huge wheels.
Comparing 26", 650B and 700C I don't notice much difference if the tyres are similar. My 700C lightweight currently has very efficient (10.3 watts at 60 psi according to the bicycle rolling resistance website) and relatively narrow Continental Grand Prix 5000 700c x 32 tyres, so it is faster on good road surfaces than my Raven Sport Tour with Schwalbe Marathon Supreme 42 x 559 tyres (19.1 watts for the 700c x 32 mm version at 60 psi, so probably more for my wider tyres run at lower pressures). However the Raven Sport Tour copes better with moderately rough surfaces and is generally a bit more comfortable on the kinds of roads/tracks I tend to prefer.
-
Mention of rolling resistance reminds me that with the frame changes I've also increased tyre pressures without making comfort worse and getting lots of buzz from the road surface. On the Mercury I was comfortable at 30psi with 50mm G-One Speed tyres and I'm now up to 40psi with with 35/40mm G-One Allround tyres on the Ti frame. (I'm aware that tyre size is a factor in this).
-
while I realize this thread is about a year old, maybe somebody can benefit from what I'd like to post.
I "upgraded" from an Audax Mk3 to a Mercury Mk3 two years ago. The idea was to get a fast tourer thats close enough to a road / gravel bike while still being comfortable for a few 100km days in a row.
I ended up with a dropbar built that weights in at 13.5kg with pedals fitted.
550S frame
Trek FXD carbon fork
FSA agx k-wing carbon handlebars
CaneCreek ee-silk seatpost
Wheelset: db460r rims, son in front
Schwalbe G-One allround 35mm tubeless
thorn crankset
SKS mud guards
B+M lighting
MKS Allways pedals
Fizik Argo saddle
SRAM Rival shifters + hydro discs
Gilles berthoud front rack
Getting rid of mudguards, lights and dynamo and front rack would shave off another kg or 1,5.
all in all I think the ride quality, weight, comfort and luggage capability are well balanced.
The group I usually ride with - carbon road and gravel bikes - I can keep up with. Sometimes I am a few minutes late for a meeting point, but thats most likely not the bikes fault.
(https://live.staticflickr.com/65535/53223744502_6fdae3fb12_b.jpg) (https://flic.kr/p/2p6cAXh)
-
Bike looks great Bernhard and just from a glance it's not surprising that John's weighed 50% more!
Did you weigh the Audax as a comparison?
-
I did. The Audax Mk3 was about 800g lighter.
It featured 28mm tyres, tektro rim brakes and a steel fork. I am sure Rohloff + Hydrodiscs adds weight vs the 105/deore/tektro mix I had mounted on the Audax, while frame and fork beeing lighter on the Mercury.
From time to time I think about setting up a lighter bike. Then I remember my 90ies Faggin with Chorus setup that I sold, as I always picked the Audax due to the much nicer ride quality :)
The Mercury fulfills the intended role perfectly: fast day rides and credit card tourer. It is no racer, but then thats not what it wants to be. I think of it more as a sports coupe than a racing car.
-
I did. The Audax Mk3 was about 800g lighter.
That is exactly what I would have predicted, kicking myself I didn't include that in the above post!
From time to time I think about setting up a lighter bike. Then I remember my 90ies Faggin with Chorus setup that I sold, as I always picked the Audax due to the much nicer ride quality
I've wasted a fair bit of money going down that route over the years. I can sometimes kid myself it was spent, not wasted, because I've had the fun along the way and it not like I'd have done anything else with it...
There is something nice about going for a blast on a bike built for that without all the compromises to practicality. But the stars don't often align like that for me and the last one I had covered 400 miles in three years. My Mercury does that in a poor month.
-
Bike looks great Bernhard and just from a glance it's not surprising that John's weighed 50% more!
Did you weigh the Audax as a comparison?
Some of my customisations to my Mercury such as the Ergotec AHS handlebars added to the basic weight nd because the bike cost so much I fitted a frame lock. I slowly figured out that one consequence of the Mercury being built to carry more load than me + minimal baggage meant that the frame was stiffer than I wanted. I was put off the Thorn Audax by the tyre width limitation although using 650b wheels would like increase that limit (but subject to the significantly smaller choice of rims and tyres.
When I bought my Mercury I didn't understand the finer details of bike design. I'm now slightly wiser but still learning. I've just built a drop bars + derailleur bike to see if I can improve on the poor experience provided by my last drop bar bike some years ago. The frame I bought for this build has smaller diameter top and down tubes which have made a significant improvement to the ride quality (although I'm looking enviously at that Cane Creek seatpost).
-
The Mercury fulfills the intended role perfectly: fast day rides and credit card tourer. It is no racer, but then thats not what it wants to be. I think of it more as a sports coupe than a racing car.
Yes! Actually I take a step down the range, and think of my Mercury more as a GT than a sports coupe, but then mine is set up a little more tour-ey, with flat 'bars and a steel front fork with low-rider lugs.
Either way it's a perfectly valid role for a bike to play, and if you're not racing then why ride a racer - at least now that we've got such fantastic alternatives. Great to hear that your Merc does the job you picked out for it.
-
I slowly figured out that one consequence of the Mercury being built to carry more load than me + minimal baggage meant that the frame was stiffer than I wanted. of rims and tyres.
I still think it's a shame you never tried the Mercury in a lighter build, you may have reached the same conclusions though at least you'd be comparing apples with apples. I obviously don't know how your Mercury rode, mine has always been in the Sports Tourer guise, in that spec it losses little to the steel Audax bikes I've previously owned. So little that I parted with my last Audax bike shortly after getting the Merc.
Isn't the Elan also designed to carry more than the minimum? Spa describe it as a light tourer (Amongst other things) and the experience of some on the CUK forum stretches the idea of light! I also know at least two Elan owners who previously rode traditional Audax bikes for the same rides.
The frame I bought for this build has smaller diameter top and down tubes which have made a significant improvement to the ride quality
It's a dangerous game - Taking one factor and attributing too much to it. It only really works if all other factors are equal, for example - If a frame with slightly smaller diameter tubes was also 20mm shorter and the TT was 30mm lower - Which would be the stiffer? And with the longer seatpost and stem required, which would feel stiffer? I don't know either.
It is useful to consider what suits us, what we attribute that too may help inform our future decisions, it's of dubious value to others. Whole product experience is of more use, even then there's no reason it should match someone else's. I greatly prefer my Nomad to the Ogre it replaced. I could have a fair go at explaining how I prefer it, I'd struggle to explain why.
Getting back to the weighty subject of this thread. There's 3.6kg difference between my Mercury and Nomad in their current spec, the difference in feel and experience is immense. I'm sure I've said this several times over in this thread already, weight is a consequence of getting the other criteria right, not the goal (Though it can be fun!)