samatthias

Dear bikeforums.net community

As must of us know there are twho differen mtb shimano pressfit bottom brackets: 89.5mm and 92mm.
If we look carefully into the shimano techguide we see that the description mention that the 89.5mm ist for symetric frames and uses a 2.5mm spacet to become also 92mm total width.
The 92mm should be used with asymetric frames.

So my question is: Can someone explain me why there is 89.5mm + 2.5mm spacer version and a 92mm version? They both endup in a 92mm width.
From a numeric point of you that doesn't make sense at all.

I really don't get it - is there another tecnical mystery I overlooked or I still not able to catch?

Many thanks for your answers and your time spent replying me.

best regards
Matt

duanedr 

Simple explanation: Because it's the bike business. The one new standard I do like is the T47 BB - FWIW. The benefits of threaded cups and a lot of volume for big spindles, bearings and internally routed cables (where required) is, dare I say, intoxicating. Yes, I'm 1.5 cocktails into the evening.

I find this helpful
FSA – EasyBottomBrackets (fsaeasybottombrackets.com)

dsaul

One fits in a 92mm width bottom bracket shell and the other fits in an 89.5mm bottom bracket shell. The crankset has the same length spindle on both, so a 2.5mm spacer(outside the BB shell) is necessary to take up the extra space on the spindle.

unterhausen

Do they think you might need to move the chain line over that much? There was some bike I assembled that came with spacers and I forget where they intended for them to go. Mid-range Salsa, IIRC. The shop owner consulted with Shimano, but I don't think I ever heard the outcome of that

samatthias

Thanks a lot guys for your replies. I really appreciate your effort to help me.

best regards
Matt