Thorn Mercury 650b owner review

[tyreon]

I've realised that in responding to tyreon's comments there's a bit I could add for context.

In a previous life I made a lving from reviewing the performance of recently released motorcycles, and so I'm in the habit of analysing the handling and general responsiveness of single-track vehicles.

My experience of various bicycles is broad but thin. So I'm no expert there. OTOH I have likes and dislikes that aren't wholly ignorant.

You know what feels good for you and what appears better. Thats good enough for you...and for me.

Somewhere about this forum someone was saying comparison works best for them when the comparison is over-exaggerated so that they can think 'that doesnt work'. I guess I am somewhere there. I think I know and have knowledge of some experience,but limited compared to others. I think in reviewing the set up and the personal experience of riding different cycles I would get confused. Its just me. I think I have to ride a cycle at least 10 miles to decide if it suits what I want it for and is suitable. I'm pretty sure I have faffed around with my own set up on my own bicycles to come back to what it was in the beginning. Very annoying. Whatever works for you,works for you...tho you can always faff about with stuff somewhat to come back to find your original thoughts and observations about matters correct. 

[JohnR]

My fastest ride on my Mercury was when I first got it when I took it for what I expected to be a fairly short ride which became longer and longer as I couldn't think of a reason to head for home. I think all I carried was a small saddle pack with a few tools. I then loaded the bike with a rack and rack bag so it was better equipped and, not surprisingly, the rides became slower. My recent LEJOG highlighted that the bike had become overweight compared to most so I've been trying to do some weight saving.

One move was to replace the rack and rack bag with a Carradice Lightweight Audax saddle bag supported by the Carradice Bagman. I didn't weigh everything but the weight reduction is less than 1kg. However, I was surprised to note that the bike felt faster in headwinds and cross winds so i have to assume that a saddlebag is aerodynamically more efficient than a rack + rack bag.

The other change I've made is removing the durable but heavy 50mm Schwalbe Almotion tyres and refitting the G-One Speed tyres. The front tyre is that which came off the bike last autumn and still has plenty of life but the rear one was more worn (see photo at http://thorncyclesforum.co.uk/index.php?topic=13962.msg103816#msg103816 ) so I've fitted a new tyre. The old front tyre was fairly willing to seal as tubeless but the new rear tyre needed a hundred miles on the rim with an inner tube to smooth out the kinks where it had been folded before it was willing to seal against the rim. The result is a bike that has lost a bit of weight, looks more appropriate for day trips (which is all I'm doing - even the supported LEJOG was effectively a series of day trips) and perhaps, most important, seems to go faster. The G-One Speed tyres do a much better job of smoothing out rough tarmac than the Almotions  (greater comfort encourages more speed) but I will be fitting other tyres with more tread for the winter months when the roads get mucky but first there's this trip https://www.bikeadventures.co.uk/product/uk-south-coast-explorer-2021-22/ to be enjoyed.

[GamblerGORD649]

Absolutely perfect bike there Moronic, except for 37/ 19T?? WTF. That's seriously into Can't-a-hill-a-phobia. 79 GI won't outrun an old fat dog with arthritis. LOL. It'll take you 2 days for a 1 day ride.
Get a 42T on there. That'll still be as low as anybody here.
One day I had a 30 mph tail wind and was going 27 mph in 115 GI. I also use it going up the back side of dips. You'll have ZERO momentum after waiting for speed to get down to where you can use 79 GIs. Not to mention you won't get much momentum either. I use every last gear, on any highway with hills.

My SA 3 speed has 84 GI. Yesterday I used it 13 miles straight on the flat freeway. That was mile 82 to 95 on my ride.
Cheers.

[PH]

One day I had a 30 mph tail wind and was going 27 mph in 115 GI.

Maybe instead of criticising you should learn to pedal properly
i don't mean that of course, pedal how you want, but for most people 90" is plenty high enough for 30mph.  I've no need for any gear over 100", I've no need for any as low as Moronic either, it doesn't mean either of you are wrong, just that I'm right.
 

[Moronic]

Absolutely perfect bike there Moronic, except for 37/ 19T?? WTF. That's seriously into Can't-a-hill-a-phobia. 79 GI won't outrun an old fat dog with arthritis. LOL. It'll take you 2 days for a 1 day ride.
Get a 42T on there. That'll still be as low as anybody here.
One day I had a 30 mph tail wind and was going 27 mph in 115 GI. I also use it going up the back side of dips. You'll have ZERO momentum after waiting for speed to get down to where you can use 79 GIs. Not to mention you won't get much momentum either. I use every last gear, on any highway with hills.

My SA 3 speed has 84 GI. Yesterday I used it 13 miles straight on the flat freeway. That was mile 82 to 95 on my ride.
Cheers.

Helpful comments from a review perspective, thanks. Will help people get a sense of what gearing to choose.

A few things come into it. Rider strength is one factor. Expected terrain is another. Expected load is a third. Accustomed cadence, as PH notes, is one more.

A related element is the ease and low cost of re-gearing the Rohloff.

I was coming to the Merc with weak legs, and with the prospect of a self-supported camping tour before the end of the year that would incorporate a couple of Australia's stiffest "alpine" climbs. In addition, I was excited to be able to gear that low with no related problems of chain management (shifting on to tiny front cog, needing huge rear mech capacity etc).

Further, my typical day ride incorporates no flat, straight, smooth sections whatsoever of more than 200 metres, and is well protected from winds. There are only three brief points on my 70km out-and-back where I could wish for more than 77 gear inches, at my starting level of strength.

Plus, that 70km was around my endurance limit for a day. If I'd had the strength to put in 95 miles (155km) or more I may well have geared taller.

And especially if I expected a lot of smooth, flat riding. I've had occasion recently to cover a few km of smooth tarmac with a gentle downhill grade and mild tailwind and yes indeed, I can't maximise those advantages because I spin out.

Otoh that is not such a bad problem to have, and especially if you've no wish to set records. I'm not convinced either that a top of 77 inches costs me much momentum on dips - although again that will be partly because I'm not strong. There is a good example on a route I've adopted recently, and I doubt there's much difference between my pedalling up the far side at 100 inches until I need to shift down, and my waiting until my speed falls to a level I can match at 77 inches.

As I get stronger - and that is happening fast - I may well add a few teeth at the front as you suggest. Otoh I may not, given that I doubt the bike will see many long, flat, smooth stretches of bitumen. I've specced it for cycle-trail day rides and gravel-road and trail multi-day tours.

While elapsed time and momentum on dips are relevant, I suspect the main thing I miss from low gearing is that very opportunity to whiz along for kilometres on end in top gear, wind-assisted and pedalling at a sustainable cadence. I have done that on other bikes at other places and times and it's a fantastic feeling. If my expected use envelope predicted a lot of opportunity for that, I'd be more motivated to gear taller.

[Moronic]

One move was to replace the rack and rack bag with a Carradice Lightweight Audax saddle bag supported by the Carradice Bagman. I didn't weigh everything but the weight reduction is less than 1kg. However, I was surprised to note that the bike felt faster in headwinds and cross winds so i have to assume that a saddlebag is aerodynamically more efficient than a rack + rack bag.

The other change I've made is removing the durable but heavy 50mm Schwalbe Almotion tyres and refitting the G-One Speed tyres. The front tyre is that which came off the bike last autumn and still has plenty of life but the rear one was more worn (see photo at http://thorncyclesforum.co.uk/index.php?topic=13962.msg103816#msg103816 ) so I've fitted a new tyre. The old front tyre was fairly willing to seal as tubeless but the new rear tyre needed a hundred miles on the rim with an inner tube to smooth out the kinks where it had been folded before it was willing to seal against the rim. The result is a bike that has lost a bit of weight, looks more appropriate for day trips (which is all I'm doing - even the supported LEJOG was effectively a series of day trips) and perhaps, most important, seems to go faster. The G-One Speed tyres do a much better job of smoothing out rough tarmac than the Almotions  (greater comfort encourages more speed) but I will be fitting other tyres with more tread for the winter months when the roads get mucky but first there's this trip https://www.bikeadventures.co.uk/product/uk-south-coast-explorer-2021-22/ to be enjoyed.

John your Merc looks fantastic in that shot - shows me how sweet a small-frame 650b version can appear, and even in red.    The black-and-tan tyre combination does no harm either.

Interesting comments on the saddlebag vs rackbag. I'd have been surprised too. I'm still enjoying my Tubus Vega and Ortlieb Trunk Bag combo though(1340g all up plus contents), and it is very easy to forget they are there.

[JohnR]

John your Merc looks fantastic in that shot - shows me how sweet a small-frame 650b version can appear, and even in red.    The black-and-tan tyre combination does no harm either.

For the record the frame is described as "Thom Mercury MK3 Frame - Red lmron - 55cm-L for 46 mm Forks with 700c / 650B / 26 inch Thom Mk3 Steel Disc Fork- Red lmron - 48mm Offset A." I bought it ready built as a demonstrator but it also features in Thorn's brochures.

Schwalbe seem to have changed the G-One Speed tyres to have the tan sidewalls. I've got another waiting for when the front tyre needs replacing (but by then I'll probably need yet another replacement on the rear which seems to wear faster so I need to look out for another at a nice price).

[Moronic]

At the risk of triggering a long discussion on lighting, I'll comment briefly on the SON dynamo and Edelux II headlamp Thorn offers for the Mercury and other models as an accessory.

I find drag from the hub imperceptible - with the light set to auto, where it switches on automatically even in persistent shadow in daytime, I have no idea whether the light is on or off.

Quoting myself here from earlier in the thread because a funny incident the other day threw further, um, light on the question of hub dynamo drag.

I'd been running the headlamp on 'sensor', but had noticed that it would switch on in mild shadow. So for an early afternoon ride I decided I would switch it off. And then forgot to do so. As I cycled along a local cycling path I remembered my plan and realised I could probably turn the light off from the saddle. Which I did.

Sure enough the bike did feel like it was running along a little more easily, and I said to myself that the dynamo drag was probably something you got used to, hence did not notice, but it was significant nonetheless and it felt great to have freed myself from it. A few kilometres down the trail there was vegetation cover that might have switched on the light had I left it on Sensor and I reflected again on how swiftly and easily the bike was running now that I'd turned the light off.

You can probably giess what's coming. On the way home I elected to stop at the crest of a climb and take in a view. Parking the bike I noticed that the light seemed to be on. I looked carefully. It was on! I looked at the switch. Operating it from the saddle I had evidently got disoriented and moved it in the wrong direction: at the moment when I believed I had switched it permanently off, I had in fact switched it permanently on, and it had remained on since.

Yes, immediately I switched it off. Did I notice, this time, a liberating sense of ease? No. I enjoyed the downhill from the crest and then cycled the rest of the way home, forgetting even to monitor my intuitions about rolling resistance.

And so that's how much difference a SON dynamo hub makes to your sense of smooth progress. 

[PH]

And so that's how much difference a SON dynamo hub makes to your sense of smooth progress. 

Yes, but if you get home and realise you've unintentionally ridden all day with the lights on, you can imagine how much faster you'd have been if you'd turned them off.

[Moronic]

A yes of course, and with much wailing and gnashing of teeth,    At my pace roughly 0.25km/h and I could spend a whole evening attempting to imagine just how much faster that is.

While we're on slow travel, I'll add a comment on gearing. I'm continuing to get stronger, and so I resort to my 15-in bottom gear less and less often.

However, I tackled a steep climb yesterday that was maybe 15 min of pavement and gravel, and did use my lowest ratio. I spent much of the climb congratulating myself on just how useful that ratio was. It feduced the torque demand enough that I could enjoy the climb rather than suffering it. Steering was no problem whatsoever.

[Moronic]

Well the moment you've all been waiting dor is here - I'm about to take my Mercury on an actual tour, starting Firday. It is Wednesday night and I'm on holiday but still havent packed. I have however ascertained that a Thermarest sleeping mat rolled up in a tarp will fit securely between my Ortlieb Trunk Bag (it's a rack bag) and the seat tube and post, which means I can probably get away with just Ortlieb front rollers on low rider racks and the Trunk bag, for this trip of a few hundred kilometers in very clement weather.

Likely the report win't post for a week or two, but who knows - perhaps I'll be bored and upload as I go. Meanwhile, readers can learn that Thorn has earned a wagged finger over the past couple of months for failing to tighten adequately the bottom bracket bearing, which has caused me grief I didn't expect to bear on a three thousand pound bicycle. The whole saga is reported on this forum here, and ends happlily.

Hazard of buying internationally. If I'd had a local bike shop build up the bike, they'd have caught the error. I didn't, which was just about ignorance. I am getting it though that a Rohloff Thorn is for those who understand and appreciate mechanical things. More to come.

[Matt2matt2002]

Great news.
Your route? Approximately.
As much as I'd like the a day by day progression please make ' enjoying the tour' number one priority.
It's your time.

You only live once, which is enough if you do it right. - Mae West

[PH]

yay, hope you have a good one!

[John Saxby]

Enjoy, mate! 👍

Seriously envious here: cold-dark-wet, snow &/or freezing rain in the offing, time for my Rohloff's annual oil change.

[Moronic]

So the tour is complete, and the story of the tour can be found on the Tours subdivision of this forum, here. Thanks for all the well wishes, and Matt2matt yes we did prioritise pleasure, as readers will see.

There are some comments about the bike but the tale focuses mainly on the six-day journey. I learned a little bit more about the bike on this trip but not all that much.

First, here is how it was loaded. Ultimately, this configuration fell under the classification "Tried to be clever".



Tellingly, I can't even remember what I'd thought would be so clever about it. Possibly I was worried that if I didn't do it this way I would have too much space, as I possessed only two Ortlieb Back Rollers that I could have substituted for the Trunk Bag.



Taking only the three bags left me very tight for space and I ended up with 4kg on each side of the fronts rack. So here is the first observation I can make about the bike: the ST fork handles 4kg a side with aplomb, but the low-speed steering does get a bit weighty. Doubtless that is because Andy Blance went for a mid-trail geometry rather than the presently fashionable low-trail, so that the bike would steer nicely unladen. Andy observes in (I think) the Thorn Megabrochure that the Mercury is designed to carry most of a load at the rear.

I'll note though that there was no particular problem with the steering being loaded in this way. It just felt unnecessarily heavy - unnecessarily, given that I coukd have carried much more of the weight at the rear if I'd had more space.

Also, the heaviness became more obvious as my speed decreased, and it was most noticeable on steep climbs. On steep descents, the extra weight probably helped. Certainly, the Mercury steered beautifully through through high-speed bends when laden this way.

What else? It was nice to be bolting on the front racks, because the bosses were perfectly placed and maximally available. Where my late-'90s high-end Trek hybrid supplied au unthreaded through tube in the fork that accepted a long bolt that tightened only against the tube, the Mercury has a threaded lug on each side.

I learned that on corrugated gravel roads the bike rides terribly unless you drop the tyre pressure well below maximum, and beautifully when you do. More detail on that one is here.

Finally, there were no issues at all with ridgidity under the 12kg load that I carried. This was made particularly plain on the several winding high-speed descents we encountered. I had absolutely no sense that the bike was struggling to keep its wheels in line under the load (my body weight was about 84kg). Rather, it felt magnificent and steered perfectly. Andy rates this model as capable of carrying 18kg with relaxed, sweet handling on rough dirt roads and I could have reached that figure by adding just 6kg at the rear. I found no reason to doubt that assessment.