SHIMANO Bottom Bracket BBR60-68mm English Thread.

Product Information

ISO 6695: Cycles– Pedal axle and crank assembly with square end fittings– Assembly dimensions. International Organization for Standardization, Geneva, 1991. (also: British Standard BS 6102-14)

Trek introduced the proprietary BB90 standard in 2007 on the revamped Madone and soon followed with the mountain bike-specific BB95. So it’s mostly eyeballing and trial and error. Some very rough guide (what I often try with first) would be:In concept, at least, all of the standards we’ve covered are functionally sound. But the realities of relaxing tolerances can create other issues. Other notes Threaded shell can be made with better tolerances and can be replaced if it wears out. CeramicSpeed now offers a fully integrated bearing (akin to T47) that will fit 30mm spindles The explosion of standards is not good for consumers or dealers,” Doyne continues. “The bottom line is that bike companies are driving the standards. Threaded systems have very few limitations — they are easily cleaned and repaired at the shop level, and they do not affect the bearing fit.” Scott US marketing and PR director Adrian Montgomery touts similar reasons for his company choosing BB86/92 over other standards:

In terms of both BBs and cranksets, of course. There are so many (in)compatible standards and how not to get confused or get mismatching equipment? Just follow these simple steps:

Table of BB standard and compatible cranksets of different standard (all the BBs accept the same standard cranksets, of course, others require an adapter, as is explained in chapter 3): BB standard Campagnolo and SRAM offer BB30 cranksets, as do FSA and other groupset makers. But Shimano has never joined the BB30 party, preferring to promote its own press-in bearing standard. Which is why you’ll often see bikes sold with FSA chainsets in BB30 bearings, but otherwise using Shimano mechanicals.

Cranksets with 24 mm spindle diameter are the most versatile and, with the right BB, or adapters, can fit almost any frame. The 30mm bearing is a good choice when using thinwall aluminium spindles,” he says, “and the narrow bearing stance (relative to outboard bearings) works perfectly with our carbon arm design needing to make the turn into the spindle. The OSBB is basically the same as BB30 but with a little tighter tolerances and a 0.5mm difference in the clip-to-clip dimension. Cranks of both systems are compatible with each other.”

SRAM DUB bottom brackets (Durable, Unifying Bottom Bracket)

The idea is simple, by moving the bearings outboard of the shell, you can then use a much larger spindle. Currently, 24mm is the accepted norm compared to square-taper’s relatively minuscule 17mm diameter. Cranksets with 30 mm wide spindles won’t fit into frames with BB86, or BB90 BBs, but with correct BB some can be made to fit into threaded frames. Specialized uses PF30 for its high-end mountain bike, confusingly also calling it OSBB though it is a different standard to the OSBB standard found on its road bike. And here's where my problem is, I have no idea whether a BB I'm considering will fit the bike or not.