Author Topic: Looking for a lighter Rohloff bike than my Mercury  (Read 4656 times)

JohnR

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Looking for a lighter Rohloff bike than my Mercury
« 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.
« Last Edit: October 21, 2021, 08:20:15 PM by JohnR »

brummie

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #1 on: October 21, 2021, 07:37:11 PM »
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 !
« Last Edit: October 21, 2021, 08:44:15 PM by brummie »
 

mickeg

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #2 on: October 21, 2021, 08:22:51 PM »
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?

PH

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #3 on: October 21, 2021, 09:23:30 PM »
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.
« Last Edit: October 21, 2021, 09:25:41 PM by PH »

Moronic

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #4 on: October 22, 2021, 04:26:17 AM »
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.










« Last Edit: October 22, 2021, 04:32:52 AM by Moronic »

Danneaux

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #5 on: October 22, 2021, 08:02:02 AM »
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.

martinf

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #6 on: October 22, 2021, 08:49:16 AM »
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.

Moronic

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #7 on: October 22, 2021, 09:28:07 AM »


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?  ;)

geocycle

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #8 on: October 22, 2021, 10:42:03 AM »
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.
 

PH

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #9 on: October 22, 2021, 10:49:01 AM »


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.

PH

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #10 on: October 22, 2021, 10:55:41 AM »
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  ;)

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #11 on: October 22, 2021, 02:36:35 PM »
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.

mickeg

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #12 on: October 22, 2021, 05:16:21 PM »
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. 

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #13 on: October 22, 2021, 07:02:27 PM »
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?

mickeg

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #14 on: October 22, 2021, 10:34:11 PM »
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.