126mm freewheel hub to 120mm??
So I'm in the process of building my first fixie. I'm considering making a bumbike rear wheel (standard freewheel hub and loctite) with some old 126mm wheels. I bought an old mercier with 120mm rear spacing. Is it bad to force the 126 to fit the 120 dropouts? Does anyone know if there are such thing as narrow spacers to get it down to 120mm?
Finally, I've read that you shouldn't mix and match the widths of the cogs/chainrings/chain?? Can someone confirm this?
there's a good chance there are spacers on the freewheel hub that you can just remove to get it down to 120. you can also cold set (http://www.sheldonbrown.com/frame-spacing.html) the frame.
you can mix 1/8 chain with 3/32 cogs and chainrings but not the other way around. it probably isn't ideal, but it works. some people complain about more noise because of it but i'm not sure how much of that is actually the mismatched drivetrain's fault.
don't pedal backwards...
Mixing chain/cog sizes is no big deal (except that you can't run a 3/32" chain on 1/8" cogs and rings). I run a 1/8" cog and chain with a 3/32" ring and have zero problems with it.
A 126mm hub should be off-center to better accomodate the freewheel. You can usually just remove the spacer from the drive side and be at or much closer to 120mm. Even if not, stretching each set of stays by 3mm won't hurt anything, but will be a pain. Cold-setting the frame to 126mm is pretty easy to do if yo are careful about keeping things aligned and you don't mind doing it to your frame.