Just trip along to your LBS and see what they’ve got on the shelf. BMX hubs are genreally the same width so that the forks are compatible with all hubs, i think moutain bike hubs do come wider, particularly if they’re tricked for fitting discs and that kind of stuff.
MTB hubs are wider than BMX ones, most will be available as a 36 hole, sealed bearings are quite common, and to get the right size axle, it’s just a matter of asking. 14mm axles are fairly easy to come across, 20mm is the new fat shit the Down hill riders are using, but 30mm… I’ve never seen that before
yeah, the 30mm hub is fork specific for the Foes…something. Beefy as can be. It looks like a more standard size is 10mm, which is something of a reason for everyone switching to 20mm. The biggest problem is that a big portion of non-20mm MTB hubs are quick release, which is definatly not ideal for a BC wheel. I know you can convert one way, but I’m inclined to say it’s 20mm to QR…it’s possible that you could do it the other way though shrug. The forces on a bike wheel are pretty big when you decide to do a 20’ drop, keep that in mind ;-). I don’t know how you could bend or break a 20mm axle on a BC wheel…