Looking to replace the PF30 BB with a Praxis.

But from what I can the Praxis sets the bearings outside the frame just like an external BB.

However that would then make the width of BB shell approximately 2 cm wider. Which leads me to wonder if my crankset spindle would be long enough.

Any ideas?

Praxis is a BB30 to Shimano/GXP/Campag converter IIRC, so no if you have a FSA crankset in there as they have different widths and diams.

That’s also why you need adaptors to fit Shimano to BB30, iirc

Yes, the bearings are external to the shell. I’m using a Shimano crank in a Praxis PF30 BB, works perfectly.
What crank are you planning on using?

BB30 to Shimano converter here, easy to fit and works well. Simple to replace the bearing in.

Wanted to use my current cranks which are Shimano FC-R565. As far as I can tell they are Hollowtech II which means they should be fine. But to me it seems that the bottom bracket shell plus the extra width of the bearing cups would be too wide for the crank spindle.

If your cranks are Shimano then you won’t currently have a PF30 in there (unless there are also adaptors present)

Are you sure its PF30, it could be PF41/BB92? Measure the nominal diameter of the ID of the BB shell: BB92 = 41mm, BB30 = 42mm, PF30 = 46mm

Sorry I should have mentioned its a road bike. The current BB is a Shimano BB-71 which I think makes it a BB-86 which I thought was a PF30 type. But it seems BB-86 and PF30 are different standards altogether. Confusing stuff.

Yup, BB-71 is BB86/PF41 – the problem is some bike makers also adopt different terminologies for the same thing.

I have the Praxis OSBB (specializeds BB£0 equiv) in my Roubaix, the original BB lasted less than 400 miles before it was squeaking, the Praxis running with Ultegra cranks, has done more than 10000 miles and is only now starting to grind a bit.