Trying to understand BB's + cranks

Chrystal

Retro Newbie
Hi

'94 Marin Bear Valley SE. It has STX Se cranks etc, however I need new ones. Can I get new Shimano ones? would they go on an existing BB or do I have to replace the whole lot? Are new BB's compatible with old frames or are the thread patterns different?

Im new to this so any help appreciated, thanks. I have looked at sheldon brown but am confused!
 
cranks

keep it simple to start with. you need new cranks so, look out for something similar on this site as it will come with advice thrown in.

what you need.....

a square taper, triple chainset with probably 175mm length arms( this number can be found on the rear of the arms towards the pedals) you also may have 170mm so, try and match those but, not essential!

you may find nos (new old stock) around but prepare to pay good money. used but good nick will suffice. one option is replace the rings rather than the whole thing but, let us see the chainset first to determine bcd and availability! stx is generally service friendly though.

you may have read up on chainsets and bottom brackets that command a certain chainline etc..etc.. just start by matching what you have or atleast a similar period and go from there. remove what you have, stick up a picture in the wanted section and ask for a suitable replacement.
as for the bottom bracket. if it feels smooth with no real play in it then leave it in. if it clunks about then it may be worth replacing as the cranks would be off already(efficient me ya know) ;)

once bb is out simply measure what axle length you are faced with(total length/ end to end). the shell width will most likely be 68mm. you need ENGLISH thread where, new ones are compatible with old frames. plenty around, again the wanted section on here will bring up many a choice and advice.

a shimano bb in a 68 x something-millimetre(square taper) a un 52/53/54 would be fine. again stick up a pic in the wanted and the 'team' will advise.

confused? don't be! we will help.
 
Square taper cranks are still made and sold. It depends on what you want. The shimano square taper cranks tend to be the lower end range for cheaper bikes. They are ust a bit heavy but work.

There are high end square taper cranks avaiable new. Middleburn still them for example.

However why buy new when you can get period second hand. Is it the cranks arms that need changing or is it the chain rings?
 
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Thats great thanks. I need new cranks and BB as they both were siezed and are now damaged, chainrings have gone as well. I want to keep it as standard as poss so will look at getting second hand cranks (hope for STX SE).

I ridiculously thought everything was standard!
 
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