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Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

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Old 09-03-11, 09:07 AM   #1
elfneedsfoodbad
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Sturmey Archer S2C on a Brompton?

I'm looking at picking up my first Brompton shortly and I was just wondering what customisation options are available. I've seen some gerat stuff done to Bromptons on the threads here. Has anyone fitted the S-A S2C Duomatic hub and, if so, how does the coaster brake perform with the chain tensioner? Maybe some has fitted the regular S2 without the coaster brake option?

(Of course, I haven't even cycled it yet - just an eager question getting carried away with what I'm seeing here)
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Old 09-03-11, 09:26 AM   #2
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Nope, chain tensioner is not helpful, on the back pedal brake.
need a frame with a rigid way to tension the chain .


you can fit a crankset and use a 52t on the inside.

Older Campagnolo cranks would be good .. 144bcd.
chainrings don't have shifting ramps and pins so can be flipped over.
arms are straight
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Old 09-03-11, 03:00 PM   #3
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An S2C Brompton has been done. See post #57 in this thread: http://www.bikeforums.net/showthread...rcher-S2C-More

I have a Brompton M1R that I'm considering giving the S2 (non-coaster) treatment. The main consideration against using the S2C is that pedal orientation is important to the Brompton fold and you can only move the pedals forward on a coaster-braked drivetrain.
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Old 09-03-11, 05:42 PM   #4
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lexm the new sram automatic is out.
http://www.bikeforums.net/showthread...M-A2-Automatic
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Old 09-03-11, 07:38 PM   #5
elfneedsfoodbad
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@lexm: Thank you so much. What a great community you all have here. For some tech reason those pictures weren't viewable by me on that thread the last time I looked and I passed over that post and seem to have been direct-messaging the wrong people.

Pedal orientation issues aside, it would seem that the chain tensioner does not totally rule out the coaster brake after all? (this is pipe dream stuff just at the moment but it's fun to dream - that cable-less look is so clean!)

Last edited by elfneedsfoodbad; 09-03-11 at 07:46 PM.
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Old 09-03-11, 07:49 PM   #6
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@dynocoaster: I can't find the relevant information on the SRAM site - the thread you refer to seems to suggest the OLN dimension to be 120mm. Am I correct in understanding this? From what little I know, this sounds a little wide for the Brompton rear triangle (I've read it ranges from 109mm to 112mm, depending on vintage).
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Old 09-03-11, 08:00 PM   #7
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Custfold over at Brompton groups has done the S2C on Brommies. He recommends that the chain be absolutely as short as possible, and even that a chain guide might be needed to prevent the chain from falling off when it goes slack during back-braking.
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Old 09-04-11, 06:43 AM   #8
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It does work and I have tried it. The fit of the brake arm on the frame is a little out of kilter.

I also have an original Fichtel & Sachs that fits much better. I am told the derailleur chain tensioner works better with these hubs.

In the end I settled for the two speed deraileur for my Brompton which provided the lightest upgrade/downgrade from my S/A 3 speed to 2 speed. I also had to swap out the main chain ring to a 54T as the 50T won't give you a high enough gear.

The S2C is quite heavy with coaster brake.

The new SRAM A2 is another option I guess.

Jerry
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Old 09-04-11, 07:29 AM   #9
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Doesn't a coaster brake cause problems when folding, i.e. it's necessary to back pedal to arrange the cranks properly?
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Old 09-04-11, 10:08 AM   #10
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The rear triangle may need to be spread to make it fit. The SA S2 has the same width.
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Old 09-04-11, 12:27 PM   #11
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My thought on the Sram is that it is automatic and without a coaster brake shouldnt be a problem on a bike with vertical drop out.
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Old 09-04-11, 02:26 PM   #12
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Quote:
Originally Posted by Dynocoaster View Post
lexm the new sram automatic is out.
http://www.bikeforums.net/showthread...M-A2-Automatic
Thanks, Dynocoaster! I'm on it like white on rice.
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Old 09-04-11, 02:32 PM   #13
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Originally Posted by Dynocoaster View Post
The rear triangle may need to be spread to make it fit. The SA S2 has the same width.
The S2 comes in two versions, one with a 120mm OLD and one with a 110mm OLD and a shorter axle. See: http://www.sturmey-archer.com/produc.../id/57/specs/1

OLD for the S2C and B2C is 116mm, according to the same site.

Last edited by lexm; 09-04-11 at 02:40 PM. Reason: Pedantry.
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Old 09-04-11, 03:54 PM   #14
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Don't worry about having to backpedal when folding a Brommie - when the back wheel is under, you can pedal forward to get the cranks set correctly.
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