BMX, kids and huffy type department store gaspipe bikes use a large diameter, unthreaded bottom bracket shell. To confuse things a bit further, I think there are two slighlty different sizes of shells used. Design is principly to accomidate (cheap and heavy) one piece cranks. Better quality BMX cranks are three piece, but with large diameter unthreaded (press in) bottom bracket. There are adapters that allow the use of a standard threaded road bottom bracket in the unthreaded shell, I think this is what BMX riders think of as a "euro" conversion. THis mostly done so that it is possible to use square taper road cranks on a BMX frame. I dont think you are likely to ever find a bottom bracket that will allow the use of the splined BMX spindle into a french threaded road frame or a french threaded BB with splined spindle to accomidate the BMX cranks.