barbonator said:
i have an old italian fixed gear conversion but
i have cottered cranks and the cotter pins
are getting worn out so i might buy new ones.
But i'd rather just get a new bb and replace
my cranks
what sizes can i use
should it be a italian threaded, with this size
70width 36mm x 24 tpi
like this on sheldon brown -Shimano BB-UN54 square tapered Italian
anyone else do this?
can i even fit a modern bb?
Yes -- you can/must use ANY contemporary Italian threaded BB (36x24) ...
You just have to 'remember' that the FIXED CUP is also
right hand threaded ...
AND, choose a 'matching' crankset.
N.B. Campagnolo & Shimano have slightly different square tapers. SOME cranks use symmetrical spindles, others don't. Also, for example, a 118mm spindle may be used on some double cranks while the
same 118mm spindle might be used on some triples! So, while you may be lucky in randomly selecting a square taper BB & crankset, you can't be sure you'll get a combination which will work together optimally ...
So, 102mm Campagnolo BBs can only be used with Campagnolo Record & Chorus cranks from the past 10 years or so ... there may be a Sugino crank that uses the 102mm BB ...
Most-if-not-all Sugino cranks use the Campagnolo (ISO) taper.
OTHER Campagnolo cranks use longer, asymmetrical spindles. These cranks can be mounted on asymmetrical SHIMANO BB spindles as long as you understand that the crank arms will be a few millimeters further outboard on each side ... at the moment, I have a CAMPAGNOLO MIRAGE crankset mounted on an asymmetric, 113mm Shimano spindle.
A Shimano crank (or, equivalent) will bottom out on a Campagnolo taper. Most Shimano cranks use asymmetrical BB spindles.
About the only BB type that is hard to find with Italian threading are the ISIS BBs, and you should consider that to be a-good-thing because the ISIS BBs are, IMO, the least desirable/reliable of all the BB types due to poor bearings.
FWIW. I'm one of the few people, apparently, who like the Octalink BBs.
