CAAD13 BB30 help?

[ridethecliche]

Err... Follow up question...

Are all the cannondale SI Cranks cross compatible if you use the correctly spaced 'BB'?

So no difference between actual BB30 and BB30A cranks other than the length of the metal BB that connects the two arms right?

[herb5998]

Depends on the year, older SI cranks aren't wide enough for BB30a. But most modern items should work without issue.

[ridethecliche]

Originally Posted by herb5998

Depends on the year, older SI cranks aren't wide enough for BB30a. But most modern items should work without issue.

What do you mean the cranks aren't wide enough? Isn't it just the connecting metal bottom bracket that needs to be long enough?

[tctyres]

Originally Posted by ridethecliche

So no difference between actual BB30 and BB30A cranks other than the length of the metal BB that connects the two arms right?

A BB30a crankset is offset for the asymmetry. They are only cross compatible if you have adjusted for the asymmetry of the chain line in swapping the cranksets. Even then, I'm not sure I would do it because the NDS crankarm would sit differently and not engage enough of the spline on that side.

Edit: I only know this because I screwed up and bought the wrong Wheels Mfg adapter for my shimano crankset installation on a CAAD12.

[ridethecliche]

Originally Posted by tctyres

A BB30a crankset is offset for the asymmetry. They are only cross compatible if you have adjusted for the asymmetry of the chain line in swapping the cranksets. Even then, I'm not sure I would do it because the NDS crankarm would sit differently and not engage enough of the spline on that side.

Edit: I only know this because I screwed up and bought the wrong Wheels Mfg adapter for my shimano crankset installation on a CAAD12.

I'm confused...

I was referring to using a cannondale SI bb30 crankset (vs bb30A)

The token thread together BB I'm using is for bb30a so I think I believe it takes the asymmetry into account so as to not make your stance lopsided!

[tctyres]

Originally Posted by ridethecliche

I'm confused...

I was referring to using a cannondale SI bb30 crankset (vs bb30A)

The token thread together BB I'm using is for bb30a so I think I believe it takes the asymmetry into account so as to not make your stance lopsided!

Chainline isn't "stance" or Q. Chainline is the relationship of the chainrings to the frame. You need to figure out where that is relative to the bottom bracket if you're mixing and matching bb30/bb30a cranksets/frames. All you need is a ruler.

My hunch, without proof, is that a BB30 crankset on a BB30a frame will move the chainrings outboard while leaving space along the drive side of the bottom bracket (hence the need for shims). Even though the spindles are the same length, the non-drive side arm won't be fully engaged with the splines.

[ridethecliche]

Ugh. It's still clicking and I can feel it. Same spot in the pedal stroke on the NDS.

Time to take apart the dang BB...

Originally Posted by tctyres

Chainline isn't "stance" or Q. Chainline is the relationship of the chainrings to the frame. You need to figure out where that is relative to the bottom bracket if you're mixing and matching bb30/bb30a cranksets/frames. All you need is a ruler.

My hunch, without proof, is that a BB30 crankset on a BB30a frame will move the chainrings outboard while leaving space along the drive side of the bottom bracket (hence the need for shims). Even though the spindles are the same length, the non-drive side arm won't be fully engaged with the splines.

Yeah sorry I totally misread what you said.

[tctyres]

Ooof ... sorry.


Yeah, if you get it together, it's tight, and shifting is good, I wouldn't worry about it.

[herb5998]

Originally Posted by ridethecliche

What do you mean the cranks aren't wide enough? Isn't it just the connecting metal bottom bracket that needs to be long enough?

Spindle lengths for SI cranks varies (6 lengths in total based on the application). 109mm is the 68/73 Road version.

[ridethecliche]

Originally Posted by herb5998

Spindle lengths for SI cranks varies (6 lengths in total based on the application). 109mm is the 68/73 Road version.

Haha the metal bottom bracket thingy I was describing is called a spindle. Who knew...

It's been a day lol