Know the rules The Paceline Forum Builder's Spotlight


Go Back   The Paceline Forum > General Discussion

Reply
 
Thread Tools Display Modes
  #31  
Old 05-14-2024, 03:38 PM
ridethecliche ridethecliche is offline
Senior Member
 
Join Date: Jul 2009
Location: Philly Philly!
Posts: 2,359
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?
Reply With Quote
  #32  
Old 05-14-2024, 08:50 PM
herb5998 herb5998 is offline
Senior Member
 
Join Date: Oct 2013
Location: Montreal, QC
Posts: 1,659
Depends on the year, older SI cranks aren't wide enough for BB30a. But most modern items should work without issue.
Reply With Quote
  #33  
Old 05-15-2024, 07:24 AM
ridethecliche ridethecliche is offline
Senior Member
 
Join Date: Jul 2009
Location: Philly Philly!
Posts: 2,359
Quote:
Originally Posted by herb5998 View Post
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?
Reply With Quote
  #34  
Old 05-15-2024, 09:44 AM
tctyres's Avatar
tctyres tctyres is offline
Tired Member
 
Join Date: Sep 2013
Location: New York, NY
Posts: 2,383
Quote:
Originally Posted by ridethecliche View Post
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.
Reply With Quote
  #35  
Old 05-15-2024, 10:56 AM
ridethecliche ridethecliche is offline
Senior Member
 
Join Date: Jul 2009
Location: Philly Philly!
Posts: 2,359
Quote:
Originally Posted by tctyres View Post
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!
Reply With Quote
  #36  
Old 05-15-2024, 11:15 AM
tctyres's Avatar
tctyres tctyres is offline
Tired Member
 
Join Date: Sep 2013
Location: New York, NY
Posts: 2,383
Quote:
Originally Posted by ridethecliche View Post
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.
Reply With Quote
  #37  
Old 05-15-2024, 12:30 PM
ridethecliche ridethecliche is offline
Senior Member
 
Join Date: Jul 2009
Location: Philly Philly!
Posts: 2,359
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...



Quote:
Originally Posted by tctyres View Post
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.
Reply With Quote
  #38  
Old 05-15-2024, 01:06 PM
tctyres's Avatar
tctyres tctyres is offline
Tired Member
 
Join Date: Sep 2013
Location: New York, NY
Posts: 2,383
Ooof ... sorry.


Yeah, if you get it together, it's tight, and shifting is good, I wouldn't worry about it.
Reply With Quote
  #39  
Old 05-15-2024, 07:40 PM
herb5998 herb5998 is offline
Senior Member
 
Join Date: Oct 2013
Location: Montreal, QC
Posts: 1,659
Quote:
Originally Posted by ridethecliche View Post
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.
Reply With Quote
  #40  
Old 05-15-2024, 10:42 PM
ridethecliche ridethecliche is offline
Senior Member
 
Join Date: Jul 2009
Location: Philly Philly!
Posts: 2,359
Quote:
Originally Posted by herb5998 View Post
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
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:07 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.