Source
r/bikewrench•
SmokePaw

BB30 Crankset on BB30A bottom bracket

Hello, I stripped my CAAD10 frame and am going to use all of the componentry to build up a CAAD12 frame.

However, the CAAD10 is BB30 and CAAD12 is BB30A, which means that the crankset is made to fit into the BB30.

Now the BB30A is 5mm longer than the BB30 bottom bracket. So what does the compatibility look like with the old crankset? Do I need to get spacers of some sort? Would it just plain not work?

The crankset is just the standard FSA crankset that came with the bike

EDIT: Went to a bike shop and then called Cannondale Tech team. It is not compatible. The BB30 Crank will not fit in the BB30A bottom bracket. I asked if getting a 5mm longer spindle would make it work. The man on the phone said that would not, however he didn't seem to know much since he had to consult the tech team....So maybe someone with more knowledge could make it work with a longer spindle. However, for me the final answer is no.

Posted May 31, 2017, 10:20 PM UTC · edited

26
nhluhr•

Kinda ironic that the company that released the widely despised BB30 is now helping muddy their own standard.

2
yolo_for_days•

In response to your edit:

Unfortunately even if you were able to extend the spindle of your current crankset, your q-factor would still be offset by 2.5mm to the left.

1
SmokePawOP•

What's a q-factor? Is this because the bb is asymmetric?

1
Lolor-arros•

From what I've read from Sheldon Brown, you might be able to get slightly larger bearings and use your shorter crankset in the new bracket.

Add 2.5mm to the bearings on each side and you might be in luck. You should definitely wait for more advice, though, I'm a newbie when it comes to bike hacks.

-2
yolo_for_days•

This seems incorrect to me. The BB30a shell adds 5mm of width on the non-drive side of the shell, so the compatibility issue here is that the spindle of OPs crankset is too short for the wider shell. Some newer BB30 cranksets use a 5mm spacer on the non-drive side that, when removed, allows the crankset to be used with BB30a. If OPs crankset does not have this spacer, it won't be compatible with the BB30a bottom bracket shell.

5
Lolor-arros•

Ah, that's another matter entirely then! That would make it incompatible, you're right.

2