sworley

I'm not sure if these pictures are of much use or not but I'm just trying to see if this might be the right size BB for this 720. It's a Shimano UN-52 and the spindle measured 4 3/4'' or roughly 122mm when I had it pulled out. The crankset I'm running is a Sugino XD 5 bolt triple (smallest ring missing in pic for cleaning), best I can tell as they're branded Cannondale PX. Does this seem like the correct spindle length? Sheldon seems to think I can get away with a 113/118mm: https://www.sheldonbrown.com/bbsize.html

The reason I ask, the bike was slopped together with mismatched garbage parts so I have reason to suspect it's wrong and also I was contemplating an upgrade to a UN72 or better.

leecycle

BB spindle appears to be too long for a double crankset, would be correct for a triple set up; the current crank appears to be able to have fittings for a 3rd chainring.

sworley

It is a triple, the smallest ring was removed at time of photo for cleaning.

Het Volk

Actually quite amazed that as late as 1985, bike manufacturers did not know to ovalize the seat stays of road bikes (both for better clearance as well as a more stiff bike where it counts).

bikemig 

You don't live too far from me as I'm in Des Moines. Pretty much every triple I've run with shimano triples, I've ended up using a 127 mm shimano BB to make it work. This is a sugino crank and it wouldn't surprise me if you might get away with a shorter axle. That said, why not run a 127? Chain lines won't be a problem with that bike as it has 18 inch chainstays. You're q factor will get a bit wider but I don't know if that matters much.

sworley

Thanks, bikemig! I have no qualms about running a 127mm, it’s just hard to find a nicer BB like a UN72 or UN91 with such a spindle, in my brief search so far. I was also curious if this spindle length was fitting and sounds like that consensus is yes.