Bottom Bracket and Crank Standards

Browsing around the Cozy Behive, I found and article on the evolution of bottom brackets and interfaces in road and MTN bikes. Unfortunately, no mention of BMX bottom brackets. Here is the BMX-U page on BB's.

BMX has gone through the same evolution (loose ball, cartridge, press fit); the only difference being that BMX adopted the cupped, press fit US bottom bracket. Since then, we have moved independent, albeit parallel to the development of road/mtn bottom brackets. We have arrived at something very similar to the BB30 standard:

BB30: 42mm ID 68mm width

MID: 41.275mm (1 5/8") ID, 68mm width

Advantages of BB30

BB30 uses a standard metric ID, which makes off-the shelf bearings available for up to a 30mm spindle. Though it should be noted that to fit a fair sized bearing to take the extra side loads our bikes encounter, it may be best to limit spindle size to 25 mm. Even so, 25mm is larger than our existing 22, and 19mm spindles. With this increase comes the prospect of high strength 7068 or 7075 Aluminum.

Using an existing standard accepted by the rest of the cycling industry opens up the BMX market to larger manufacturers, higher technologies, and respectively, BMX companies' customer base. Hopefully, expanding their market will help smaller operations survive. Profile has a similar situation with their 48 spline cranks and dirt jumpers.