Can of Worms Mk2

Given Andy Mc has started the discussion on the various groupset manufacturers I thought I'd have an ask whether anyone has any thoughts on the various bottom brackets available.

So far my digging has shown a load of different standards predominantly arranged around either the width of the frame shell (threaded BSA vs Italian) or the internal diameter of the frame shell (ID) combined with the width of the frame shell. On top of all this you have axle size as well.

If you're going straight Shimano they only do BSA/Italian BB cups it seems otherwise you're looking at someone like Rotor with a 24mm axle bearing solution (fortunately Rotor do a chart). Rotor will also do a threaded bearing cup set-up for 30mm axle if you want to use their 30mm axle cranks.

So any comments on pros and cons?

Tony this hasn't been spawned by our discussion on Twitter, just an extension of something I've been thinking.

Probably.....now where did I put that pasty..

Liking the standard hollowtech setup....simple to install and service and so far fairly hard wearing.......BB30 etc looks to be a pain in the arse with regards servicing.

That's my current thinking Chris, after all it's predominantly frame manufacturers that have gone this way with SRAM, FSA and Rotor being main adopters on the mechanical side.

Both Shimano and Campagnolo have stuck with outside cup bearings as far as I can tell with adaptors for BB30 and PF30. Rotor do bearings that will fit the various press fit standards that will take a 24mm axle (Shimano Hollowtech) and also screw in bearing cups that will take a 30mm axle.

Some reading I found today suggests that the main reasons (unsurprisingly) for moving to these press fit set ups are cost related. Cheaper bearings, shells and cheaper to manufacture the larger 30mm axle compared to 24mm. The fact that it's lighter is almost a secondary benefit and quite a few articles suggest replacing the standard press fit plastic shells with metal ones from Rotor or one of the other companies.

Ever so slightly out on tolerances and the plastic shells will cause creaking (too small and they are a slack fit, too big and they get crushed, crack and then creak). Oddly headsets use press fit bearings but these have more clearly defined tolerances and always use metal press in shells not plastic ones ...