BMX parts question?

Question

is a european bottom bracket threaded into the frame

Answer 1

Yes....both cups are threaded into the bottom bracket shell.  

They also make adapters so that you can run a euro bottom bracket in a frame that was designed for normal units.   Also, you'll hear euro bottom brackets (outside of the bmx world) referred to ISIS, Octalink, square taper, etc.....they're just different versions of the built-in spindle.

Hope this helps.....if you want to see pics of the different kinds, check out the FAQ's section of Dan's Comp.