Originally Posted by
BluesDawg
I can't quite follow your meaning. What I was saying is that if your bike now has a 10 sp Tiagra crank, an Ultegra crank will also fit since they would use the same type of BB, either English or Italian depending on which threading your bike has (probably English). To put either crank into a bike with a BB30 shell would require some kind of adapter which would work with either one. But a BB30 crank will not fit into a frame with an English or Italian threaded BB shell.
to simplify, will a given crank fit into bikes with different bb...so the crank part itself is no different (as in different length, diameter something) just the bb is different.
so for instance I have a giant defy with an ultegra crank. it has a bb30. Can I take that crank off the giant, buy a english bb and install it all on a new bike that needs the english bb (rather than buying a whole new crank and bb)