BMX BB on MTB

[Err]

Would it be a good idea to use a BMX BB on a MTB with a suitable BB shell?

 

[stevet1]

Are you thinking of sqeezing a BMX euro BB into a standard threaded BB shell, or fitting an american BB into an american style BB shell?

 

[Err]

Both. Immediately, i can put a euro bb on my singly, but in the future i'd consider buying a frame with an american shell.

 

[stevet1]

regarding the euro BB's, BMX'ers have come to their senses - there is just not enough space to fit decent bearings in with the large axles BMX'ers use. I'd stay clear unless you find you are snapping BB axles more frequently than wearing it out.
As for the american BB shell, I love the simplicity of these - I specced one on my custom curtis BMX even though very few BMX's use them these days. But I'm not sure what the sealing against mud is like on 'em as MTB's see a lot different use to my BMX.