Originally Posted by
Greyryder
Dan's sells a number of European bottom brackets designed for BMX cranks. The Demolition BB is only available in Mid size, but BBs to fit 19mm spindles are a dime a dozen. I'd recommend either the
Profile or
Redline bottom brackets. Both are available to fit Euro style crank hangers.
One word of warning: I don't know that MTBs and BMX bikes have the same width bottom bracket shells. If they do, you should be golden. If the MTB shell is narrower, you can probably get by with extra spacers. If it's wider, the spindle may not be long enough to properly engage the spindle splines.
I'm pretty certain the BMX "euro" BB shell is the standard 68mm width. For BMX bikes, they're commonly used on Mini-BMX frames where the "stress" isn't as great.
Another potential incompatibilty: chain width. BMX chainrings are available in 3/32" and 1/8" width- you want 3/32". Since you're going for a 1x9 drivetrain, you should be OK. If it were some whackdoodle 10-speed setup (which uses a 5/64" thick sprocket) then you'd be SOL.