Hello,
It looks like an old school loose ball & cup bottom bracket and tapered spindle. If you're in need of a replacement most local bike shops keep them in stock. Make sure you also grab a spindle nut to lock it down.
The [url= http://dedhambike.com/product/sunlite-aluminum-low-profile-horizontal-square-crankarm-left-231199-1.htm ]replacement crank arm [/url]should run you $20-$30 and the nut a dollar or two.
Good luck!
Square taper crank spindle with cup and cone adjustable bottom bracket.
It's not mine. A friend is asking and I've never seen one before.
What would the bolt look like to tighten up the crank arm? Does it need a nut of some kind?
Yes, M8 (IIRC) nut. LBS will have dozens lying about.
Any square taper crank will fit, as said a nut will be needed.
What are doing? Fixing the BB? Replacing the cranks?
Any square taper crank will fit
Unfortunately not, there are two or three different taper standards, and just to complicate things the square hole in the crank is sometimes set at 90deg to the crank, rather than 45deg
That nutted spindle looks similar to either 1970s/80s Sugino or SR, but the welded frame could be much more recent and I don't know who uses them now
Replacing the crank arm, and wondering how to fix it to the bike. I assume the nut is missing.
[url= http://www.walkerscycles.co.uk/catalogue/retail/10/9/3600 ]Probably looks like this one at top left...[/url]
Thanks everyone.
If your refitting the old left hand arm after its fallen off on its own ? Don't bother it will only fall off again.
You will need a new left hand arm and maybe bb axle