cotter freedom

Slurp

I have an older bike that uses cottered cranks. Does anyone know if it's possible to replace these with more modern fittings and end the tyranny of cotter-wear? I'm guessing I'll need to replace the bottom bracket too, but is that it? Would modern bottom brackets fit on a bike that's more than 20 years old?

If anyone's done this, I'd be grateful for some pointers. Or do I resign myself to helping keeping the local bike shop in business.

redvee

You'll have to replace chainset and BB. You can upgrade to tapered, or jump bang upto date with splined BB and chainset. Can't see no reason why a new BB shouldn't fit a bike 20yrs old. The only thing stopping you will be the shell width of your frame, 68 or 73mm.

CiderMartin

You may be able to obtain a square-taper axle (try St. John's Cycles). I managed to convert an old Carlton by canabalising an old bike obtained from the local tip, so they are about

As a word of caution, some old frames have a bottom bracket thread of 26 tpi and will not take the standard 24tpi bottom bracket. Alternatively you can purchase a bottom bracket that is a fix for frames with damaged threads; do an internet search.

aracer

Plenty of choice in square-taper bottom brackets - Shimano and Campagnolo both still make them. The only problem as CM mentions is if you have funny threading - though I'd suggest that is unlikely on something as young as 20 years - that's about how old my first race bike frame is, and current standards were pretty much the norm back then.

redvee

If the BB is threaded 26tpi then you might be able to bang a taper axle in and reuse the cups along with new bearings and grease.

meagain

"funny threading" most commonly on Raleighs but if it's only 20 y.o. even one of those should be current standard threads.