Bicycle Mechanics - Single Speed problems
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11-10-02, 02:13 PM
I've put together a winter hack bike for commuting. Based on an old Peegeot road frame with mudguard clearance and eyes.
700c wheels. To make it even more bomb-proof, I decided to go single speed. 16 tooth cog at the back.
To my surprise it has been hell to set up. the chain keeps jumping off. I've tried playing about with the chain tension, but it won't come right. I tried a chain tensioner - like a single jockey wheel on spring tension, but then the damn chain would skip every time I put any hard pressure on the pedal stroke.
I expected a single speed to be a doddle to set-uop, but the bike is barely rideable.
Usually they are easy but maybe I've been lucky. Is your chainline reasonably straight? This is critical if your SS is a fixie probably not as important if you've got a SS freewheel but I still go for as straight a line as possible.
Those SS freewheels are designed for bmx chains but I've run them with road (older style 7 speed) chains with no problem. They might not work with a 9 or 10 speed chain though.
How are your drive train components? If, like many, you've cobbled this together from "parts bin" components you might have a bent chainwheel or spider. Worst-case might be a frame defect.
11-11-02, 06:05 AM
Ive had chains skip off single chainwheel setups. Modern chains seem to have a lot of sideways flex. A front mech works well as a chain guide, I scrounged mine from the used parts bin of my LBS.
11-12-02, 03:22 AM
Thanks for the help guys. It seems the chainline was not as straight as I thought it was.
The LBS fiddled with spacers on the rear axle and re-dished the wheel to get it spot on. Only charged me £10. I was well pleased.
I like the front shifter tip. might try that, and now that the chain line is straight I might try again with the chain tensioner. A gizmo called "the singulator". The chain seems fine now, I just don't fancy using the wheel clamp to control chain tension. I'd rather have the wheel right at the back of the stops and use the chain tensioner gizmo.
Spent last night setting up the lights, compter, final fiddling and was going to ride in to work today - first time in over amonth, but wimped out because it was raining so hard.
I've gone soft!
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