BB: campagnolo square taper compatible with shimano square?
 

Hi, I am trying to purchase an italian thread BB for square taper. this has become an odd item over the years; shimano square tapers BBs are getting scarce. Anyways, I am trying to figure out whether I can put a Shimano 600 crank on a square taper campy BB. I am not sure whether the spindle size is equivalent.

Well, many bike shops could order IRD bottom brackets with italian threads + JIS (Shimano-like) spindle or you could go for Phil Wood bb's.

I believe that the Shimano crank would fit a bit "deeper" on a Campy bb (ISO spindle), since the Campy bb is a tapered a bit more. Perhaps there may be a bit more wear at the crank/spindle interface over time, since it's not a perfect fit...

Also, I just saw this from the Sheldon Brown site:

"ISO/J.I.S. Interchangeability

If you install an ISO crank on a J.I.S. spindle, it will sit about 4.5 mm farther out than it would on an ISO spindle of the same length.
Confersely, if you install a J.I.S. crank on an ISO spindle, it will wind up about 4.5 mm farther in than it would on a J.I.S spindle of the same length.

Theoretically, ISO cranks should only be used on ISO spindles, and J.I.S. cranks only on J.I.S. spindles.

In practice, you can very often get away with mixing these sizes, as long as you select a spindle length that gives the desired chainline.

Taper matching was fairly important back in the day of loose-ball cup-and-cone bottom brackets, because these required regular maintenance/overhauls, and this required removal of the cranks. Every time you remove and re-install a square taper crank, the hole in the crank is liable to get very slightly larger.

This was particularly an issue when using J.I.S. cranks on ISO spindles, because over time, as the crank went on farther and farther, you could run out of taper, and the square end of the spindle would become flush with the surface the crank fixing bolt/washer pushed against. At that point, further tightening of the bolt won't make the crank any tighter, since the bolt is bumping onto the end of the spindle.

These days, however, most folks are using sealed cartridge bearing bottom brackets. With these, there is no routine maintenance required, so typically the crank will be installed once, and will stay in place unless/until the bottom bracket needs to be replaced. This greatly reduces problems of wear to the interface.

I generally avoid mixing sizes on customers' bikes, but I have a lot of experience mixing ISO/J.I.S. in both directions on my own personal bikes, and it as never given me a lick of trouble."

oh ok thanks. The things are damned hard to find now. I should buy 2 if I can find it.

actually, there still relatively easy to find -- http://store.interlocracing.com/bobrisandsqt.html (but you'd also need to order the italian cups), Phil Wood, etc.

What spindle length are you looking for? I have an Italian threaded square tapered Shimano cartridge BB (UN72) with a 115 spindle that I wouldn't mind getting rid of. I used it on my Colnago for a short time (300 or so miles) before discovering that it was my crankset that I needed to replace. It's just been sitting in my parts box ever since. PM me if you're interested.

I can't believe I'm disagreeing with the late, great Sheldon Brown, but I have had issues with putting an ISO crank (Suntour Superbe Pro) on a JIS spindle (Shimano UN-73). It was making a maddening creak with each revolution. I put in a Campy Veloce BB and it's been fine ever since.

where were you for the last 3-4 weeks..I had 3 campy bb's, Italian thread on ebay...no bids and had to relist 2 times, the chorus went for a giveaway price of 19.00 :)

and you are right, they are getting rare..

also IIRC Phil wood still makes a square taper campy hub..pricey but will last a lifetime

That's why they make a special size for each crank. You've done well.

My interpretation of the issue is that a Shimano (JIS) crank gets a greater contact area with the facets of the spindle of a Campy (ISO) because it fits onto it further. I have done this with no issues.

Going the other way (ISO onto JIS spindle), as caloso did, suggests to me a much smaller contact area. Perhaps the reason for the creakage. It seems a much more fragile setup.

Lxpatterson should be fine if he locates the right length bb spindle for his desired chainline. I have had no problem finding Campy BBs recently.