Classic & Vintage - French crank with a Shimano bb?

I placed a tapered French Stronglight crank on a tapered Shimano BB, are they tapered differently? will I have problems with it? If so is there any way (besides a Phil Wood BB) that I can make it work? (assumeing there is a problem?)

It shouldn't be a problem. Just measure your chainline for proper fit. Your Stronglight crank should be ISO taper and your Shimano spindle should be JIS taper.

Sheldon has the answer:

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.

Having cracked a Campagnolo Veloce crank at the spindle eye, possibly from mounting it on a later and larger Campagnolo BB spindle, I would avoid mix-and-match.

It shouldn't be a problem. Just measure your chainline for proper fit. Your Stronglight crank should be ISO taper and your Shimano spindle should be JIS taper.

Sheldon has the answer:

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.


I'll take Sheldons advice. :thumb: Thanks Machin Shin, no disrepect John E, but Sheldons still "The Man" when it comes to advice on bikes. :)

I'm currently using a Shimano BB with a Stronglight 104.

Take Sheldon's advice, but recognize that you're giving up around 4.5 mm of the overlap between taper and spindle, your crank bolt is 4.5 mm less "engaged" in the spindle threads, and there's 4.5 mm more "air" between the head of the crank bolt and the end of the spindle; so if your crank splits or your arms get wobbly and the sockets are galled, please don't come crying to us!

Take Sheldon's advice, but recognize that you're giving up around 4.5 mm of the overlap between taper and spindle, your crank bolt is 4.5 mm less "engaged" in the spindle threads, and there's 4.5 mm more "air" between the head of the crank bolt and the end of the spindle; so if your crank splits or your arms get wobbly and the sockets are galled, please don't come crying to us!

Why would I come crying to you or anyone else on this forum if that happens? ^^^that^^^ ending statement doesn't make any damned sense?