Author Topic: Thorn Sherpa with Rohloff  (Read 51447 times)

rualexander

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Thorn Sherpa with Rohloff
« on: January 24, 2011, 10:11:58 pm »
Got out yesterday on my Sherpa just converted to run with a Rohloff.
Very happy with the hub which I got second hand recently, quieter than expected for an almost new hub,
and the gear ratios are closer than I expected but still plenty of range from bottom to top.
Running a 39 tooth chainring and 16 tooth sprocket.
Only snag seems to be the external gear mech/box gets in the way of the mudguard stay and also
probably the rear rack which I've still to fit. The external box can't go below the chainstay
because of the long torque arm.




Blacksail

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Re: Thorn Sherpa with Rohloff
« Reply #1 on: January 24, 2011, 10:50:51 pm »
Nice.

What does the left hand shifter do?

rualexander

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Re: Thorn Sherpa with Rohloff
« Reply #2 on: January 24, 2011, 11:03:19 pm »
Nice.

What does the left hand shifter do?
Well, it still works the front derailleur, I haven't had the time to take them off yet! But I may leave them on as I am still trying to decide whether to keep the Sherpa, or put it back to derailleurs and sell it and get a Raven Tour frame.

Blacksail

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Re: Thorn Sherpa with Rohloff
« Reply #3 on: January 24, 2011, 11:14:41 pm »
oh I like the idea of a Rohloff Triple combination, that way I might bag the elusive 100 kph top speed on my local hill

geocycle

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Re: Thorn Sherpa with Rohloff
« Reply #4 on: January 25, 2011, 09:20:32 am »
That looks a good conversion Rual.  The main advantage of the raven frames is that you do away with the need for the chain tensioner. Having bent a couple of hangers and got fed up of cleaning jockey wheels this was a significant attraction for me.  How do you find the changer on the bar end?  Are the geometries of the sherpa and RT frames the same?
 

rualexander

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Re: Thorn Sherpa with Rohloff
« Reply #5 on: January 25, 2011, 10:11:31 am »
That looks a good conversion Rual.  The main advantage of the raven frames is that you do away with the need for the chain tensioner. Having bent a couple of hangers and got fed up of cleaning jockey wheels this was a significant attraction for me.  How do you find the changer on the bar end?  Are the geometries of the sherpa and RT frames the same?

Yes I know, it would be good avoid the possibility of a bent hanger, I've had that happen a couple of times on public transport years ago (and on one occasion in Australia I didn't notice and changed down gears and put my derailleur into my rear wheel breaking about eight spokes!).
It would also be good to do away with the long torque arm.
I like the shifter on the bar end, preferable in my opinion to the Thorn accessory bar method, but I am used to bar end shifters. The £40 for the Hubbub adapter is a bit steep though!
My Sherpa is a 610S so the nearest Raven would be the 612S but the geometries are a bit different in terms of seat tube angle, top tube length, and top tube slope. But probably near enough to get the same riding position with seat and stem adjustments.

sweats

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Re: Thorn Sherpa with Rohloff
« Reply #6 on: January 26, 2011, 06:04:55 pm »
Hi Rual
Bike is looking good. Pleased to see the Rohloff parts worked out well. You didn't hang about fitting them!
Regards
Chris

tourdescotland

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Re: Thorn Sherpa with Rohloff
« Reply #7 on: January 27, 2011, 01:14:53 pm »
Looks good, Im waiting on my new black Sherpa arriving... so excited.... couldnt afford the rohloff, but now i can save again and convert next year as this bike looks good... nearly as good as mines will   ::)

rualexander

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Re: Thorn Sherpa with Rohloff
« Reply #8 on: January 28, 2011, 04:35:02 pm »
Only snag seems to be the external gear mech/box gets in the way of the mudguard stay and also
probably the rear rack which I've still to fit. The external box can't go below the chainstay
because of the long torque arm.
I have found a way round this.
Further study of the Rohloff manual and looking at photos of other bikes with the long torque arm and external mech/box suggested that if I repositioned the torque arm from the inside of the axle plate to the outside I would then be able to rotate the 'ex box' further clockwise to a position where it would be less in the way.
I did this this afternoon and I think it has solved the problem. Still to fit the rack but it looks like there is now plenty of room for it.

Andre Jute

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Re: Thorn Sherpa with Rohloff
« Reply #9 on: January 30, 2011, 01:43:29 am »
Got out yesterday on my Sherpa just converted to run with a Rohloff.
Very happy with the hub which I got second hand recently, quieter than expected for an almost new hub,
and the gear ratios are closer than I expected but still plenty of range from bottom to top.
Running a 39 tooth chainring and 16 tooth sprocket.
Only snag seems to be the external gear mech/box gets in the way of the mudguard stay and also
probably the rear rack which I've still to fit. The external box can't go below the chainstay
because of the long torque arm.

Nice cabling job. I'd rather mess with the chainstay than give up that good gearbox cable run. Maybe get an uncut chainstay and bend it to suit. EDIT: I see you've changed it already. But I'll let my remark stand: a straight cable run to the gearbox is worth a small problem elsewhere.

Looking at the drive side of your bike, I'm just wondering if you cannot give up the chain tensioner. After all, a Rohloff chain is supposed to be quite slack, so there will be adequate adjustment for wear. If you used a Hebie Chainglider, the chain would essentially last forever, so the tensioner could be surplus to requirements. I don't have enough miles on the chain on my Rohloff bike to have adjusted anything, but on my two Shimano Nexus bikes the bite of the hub retainer shows that the axle has throughout remained in the same place.

Anyone without the eccentric bottom bracket who has deleted the tensioner?

Andre Jute
Visit Jute on Bicycles at
 http://www.audio-talk.co.uk/fiultra/BICYCLE%20%26%20CYCLING.html
« Last Edit: January 30, 2011, 01:48:25 am by Hobbes »

rualexander

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Re: Thorn Sherpa with Rohloff
« Reply #10 on: March 30, 2011, 06:21:36 pm »
Just back on Sunday from a week on Mull with my Rohloff equipped Sherpa.
Very happy with the Rohloff so far, probably due my first oil change now.
Since the initial photos at the start of this thread, I've changed the bars and stem to FSA Vero compact drops and a Ritchey adjustable stem and I'm happier with my riding position and will probably stay with the Sherpa rather than changing to a Raven Tour frame, at least for this year anyway.
I did try a quick experiment with the chain and see if I could get away without the tensioner but it was either way too slack or not joining up, even with a half link, it might work though with a different chainring or sprocket size.
I don't mind the torque arm now, although I haven't had any punctures in bad weather, it's no hardship to unclip the torque arm anyway.
I got the rear rack on to fit clear of the external mech box no problem.

Photos from my week on Mull here


tandemman

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Re: Thorn Sherpa with Rohloff
« Reply #11 on: March 30, 2011, 08:00:14 pm »
excellent photo set going to Mull in June really inspired nowjavascript:void(0);

Fred A-M

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Re: Thorn Sherpa with Rohloff
« Reply #12 on: March 30, 2011, 09:55:11 pm »
Indeed, an inspiring photoset, and very brave of you IMO to go camping in March.  How was the weather?
 

rualexander

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Re: Thorn Sherpa with Rohloff
« Reply #13 on: March 30, 2011, 11:21:19 pm »
Indeed, an inspiring photoset, and very brave of you IMO to go camping in March.  How was the weather?

Thanks guys. The weather was fantastic, it was more like May than March, only rain was during the night on the first night, after that dry with light winds and mild temperatures, and the advantage at this time of year is no midgies!

cake

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Re: Thorn Sherpa with Rohloff
« Reply #14 on: March 31, 2011, 07:30:51 am »
Stunning photos Rual - i could do with some of that action at the moment!