Help with bb on a mtb!!

[flying start]

I'm building a mtb it's a trek 4300sl frame I've also got a rockhopper which has a single crank up front with nine on the back!!
Will the crank and bash gard fit on the trek? Are the bb's the same thanx Lee!

 

[PpPete]

I'm building a mtb it's a trek 4300sl frame I've also got a rockhopper which has a single crank up front with nine on the back!!
Will the crank and bash gard fit on the trek? Are the bb's the same thanx Lee!

Chances are they both "english threaded" so it's quite possible you will be swop the BBs. If you are lucky they may be the same spindle length too. If not you could have chainline issues.

Dont forget that "english threaded" has LH thread on drive side, and dont force anything that doesnt want to thread in easily.