Author Topic: Looking for a lighter Rohloff bike than my Mercury  (Read 4658 times)

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #60 on: December 22, 2021, 12:31:08 PM »
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.

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #61 on: December 24, 2021, 07:11:31 PM »
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.

KDean

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #62 on: December 27, 2021, 01:05:34 PM »
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 .

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #63 on: December 29, 2021, 10:52:51 PM »
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.

PH

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #64 on: December 30, 2021, 01:32:54 AM »
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.

PH

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #65 on: December 30, 2021, 01:43:35 AM »
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.

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #66 on: December 31, 2021, 07:56:26 PM »
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.

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #67 on: February 01, 2022, 07:56:24 PM »
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.

Danneaux

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #68 on: February 01, 2022, 09:45:44 PM »
Quote
...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.

mickeg

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #69 on: February 01, 2022, 11:16:34 PM »
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.


JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #70 on: February 02, 2022, 09:02:07 AM »
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.

PH

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #71 on: February 02, 2022, 10:03:59 AM »
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.

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #72 on: February 02, 2022, 02:07:56 PM »
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.
« Last Edit: February 02, 2022, 09:15:18 PM by JohnR »

JohnR

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Re: Looking for a lighter Rohloff bike than my Mercury
« Reply #73 on: February 09, 2022, 10:58:03 PM »
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.