Pressfit Bottom Bracket

Triathlon Forum
1

Please someone help me understand what is a pressfit bottom bracket? Will they work on any bike? I have a cervelo s1 and the crankset is Ultegra will it work without an adaptor? Or will have to purchase the external bottom bracket cups? If it does work should I use it or are external bottom bracket cups better?

Thanks,

Jason

2

Have a look at your BB. If the cups are on the outside of the frame your bike has an external BB. I’m 99% sure the S1 is one of these. English thread and many have the FSA Mega exo BB fitted standard.

If the cups are inside what appears to be an oversized BB they are press fit. Although size is different. Some are BB30 some are BB90/86. It really depends on the maker, Cannondale/Specialized have a hard on for BB30.

3

Yes you are right the s1 has external bb. The pressfit bb that I have is a bb86. Which I am guessing is larger than the standard GXP because it all has to fit inside? So then the answer is no a BB86 pressfit would not work is that right?

4

sorry, I just realised I didn’t answer you question fully. no it is not suitable for your bike.

You can get adapters to fit gxp cranks to BB30 bottom brackets but not the other way. I can’t see how they could or why adapt a press fit BB external.

5

Wait a minute.

To use an Ultegra crankset on your S1 you will need a Shimano BB.

BB86 is a standard crankset without the BB cups(the bearings go right in the frame).

BB30 is different than BB86 which Rocketman is talking about. If you have 24mm spindle crankset it will fit in a standard BB frame(i.e. a Cervelo S1) but it requires an external bb.

6

Thanks makes sense. Thank you. Just to clarify.

I have a 24mm spindle Ultegra crankset and it came with a Shimano pressfit 91bb. Which I can’t use since it is 41mm but I can still use the crankset but I have to buy an english threaded external bb. Am I understanding correctly?

7

That is correct, but it needs to be a Shimano one or Shimano compatible like an aftermarket Token one for example. A Sram BB is not compatible with Shimano Crankset as the end of the spindle is shaped differently.