I have a LeMond Big Sky SLT & an Opus Triton. Every bikepedia-esque site I went on said they had incompatible bottom brackets.

When I actually read the brackets today the LeMond has a BSA. The Opus only states: BC1.37x24.

BSA has the same measurements: 1.37x24 (according to wikipedia.)

Does this mean the crank from one will fit in the other or am I missing something?

I've read a lot about all the crank differences and compatibility issues etc but frankly I can't identify what I have to know if they're different.

  • The BB's are both ISO threaded. You still need to know if the crank is splined or square tapered and the spindle length of the BB - see the Shimano cartridge bottom bracket section of sheldonbrown.com/bbsize.html for details. "As far as crank interchangeability is concerned, the most important thing is the overall length, and the offset if the spindle is longer on one side than the other (that's true of many older units.)"
    – Batman
    Jan 4, 2014 at 12:33
  • So it is a Splined crank. The length of the BB's both measure 91mm.
    – brianp
    Jan 5, 2014 at 4:46
  • It looks like the ISIS Splined crank on Sheldons page.
    – brianp
    Jan 5, 2014 at 4:59
  • I think I'm just highly confused about what is what. Only now am I realizing that the spindle is considered part of the BB and not part of the crank. I removed the spindle still attached to the drive side of the crank and thought I could just move the crank with spindle into the other bottom bracket (same 91mm length) without issue.
    – brianp
    Jan 5, 2014 at 5:12
  • I'm not sure what you have, but you may want to go to your local bike co-op or bike shop or something to see what you have and stuff. Alternatively, you may want to look at a book like "Bicycling Magazine's Complete Guide to Bicycle Maintenance and Repair" by Todd Downs for some details. Why do you want to swap the cranks anyway?
    – Batman
    Jan 5, 2014 at 6:09

1 Answer 1


Matching BB is one of the hardest jobs as a paper exercise compared to eyeballing them side by side. As suggest in @Batman comment, length and offset are both critical, yet most sellers only specify length.

As far as matching Cranks go, there are a number of systems - square taper was (an probably still is) the most common - there is some confusion over the compatibility between a couple of different standards, but it does not seem to be a problem in reality. Spline cranks come in a couple of different flavors, which are incompatible. Have a read of Sheldons webpage on the subject.

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