BB Question.

ExigeR

I have just fitted a Pressfit BB91 to my bike and am using Shimano XT cranks so 24mm spindle.

I would like to change to Sram XX1 set up.

Am i right in thinking any pressfit bb fill fit eg GXP 24/22mm or BB30 as they use the same shell but just different bearing sizes???

I also guess there are next to no differences between both GXP and BB30 and its just to to personal taste.

JohnBurt

Isn't BB30 a 30mm spindle where the bearing is a firect fit in the frame, so I guuess you will need xx1 with 24mm spindle and 91mm reach if it exists and retain your original press fit BB

oxocube1

ExigeR wrote:

I also guess there are next to no differences between both GXP and BB30 and its just to to personal taste.

The BB30 is for cranks that have a 30mm spindle, hence the name. The GXP pressfit/external bearings are for a 24mm spindle so the two are not compatible. BB30s require an inner bottom bracket shell diameter of 42mm compared to the standard 35mm that the GXP will use.

ExigeR

Yeah my road bike has that set up but the MTB use this.

http://www.chainreactioncycles.com/Mode ... elID=44225

This is the BB30 press fit.

http://www.chainreactioncycles.com/Mode ... elID=51600

Im not fussed what i use but don't want to buy the cranks and find the BB wont fit lol....

oxocube1

Yea the first link you provided is for a 24mm spindle, so a GXP/hollowtech 2 crankset. The second link you provided is for cranksets that use the 30mm spindle so BB30 cranksets. So if you wanted to use your existing BB91, you would have to get an XX1 crankset that is designed for a GXP (24mm spindle). I not 100% sure on the compatibility of XX1 crankset though.

ExigeR

I think the GXP is not the same as the Shimano in the way of a 22mm bearing on one side.

I know I will need to change the BB I guess the question is will the press fit BB30 fit or are the cups over sized.

ExigeR

Think I found it, bb30 is 46mm GXP 41mm

http://bikeresource.blogspot.co.uk/2011 ... t-gxp.html

So it's going to have to be GXP.

ExigeR

If they posted this yesterday it would have saved me some time searching the web lol.

http://www.bikeradar.com/news/article/e ... -in-36675/