Forum home Road cycling forum Workshop

BB30 and BB30a confusion

challengedavidchallengedavid Posts: 273
edited September 2018 in Workshop
thinking all BB30s were identical i purchased a new bb30 (a)?? chainset
upon fitting i realised the spindal was about 5mm longer than the old one so it did not fit!

purchased some 2.5mm shims, fitted one each side of the BB and thought job done!

that was until i realised i could not get the front mech to move far enough across to set the gears up properly

i have fitted both spacers on the NON drive side and i have setup the gears perfect but dont really want to leave it like this as it means its off centre by 5mm

so any ideas on how to get it evenly spaced with fully working gears?


thanks in advance!

Posts

  • Take it you've adjusted the limit screws correctly?

    Return the crankset and get the right one?
  • keef66keef66 Posts: 13,286
    This from the Cannondale website. They effectively started BB30 and more recently BB30A

    ".... BB30A found on the Synapse. The "A" stands for Asymmetric - the BB30A adds 5mm to the non-drive side of the BB shell for a wider, stiffer base. To accommodate the wider BB shell, the BB30A gets a longer spindle and the non-drive side crankarm angle is changed to maintain the same Q factor and even out ankle clearance on both sides. Cannondale Hollowgram BB30A cranks will work on both BB30 (68mm BB width) and BB30A (73mm bb width) by changing the non-drive side spacers".

    So what you've effectively done is correct, and is the only way to fit a BB30A chainset to your BB30 frame.

    What you haven't got is the 73mm BB shell for that "wider, stiffer base", but unless you're Andre Greipel I doubt you'll notice.

    But if the 5mm spacers on the NDS is troubling you, the only solutions are a BB30 chainset or a BB30A frame.
  • As I understand, the A means assymetric, so it is meant to be off centre. The different angle of the crank arm on the non-drive side should mean that the pedals are the same distance from centre.
    and then the next thing you know
  • A good excuse for a new bike, if ever I’ve seen one
  • keef66 wrote:
    This from the Cannondale website. They effectively started BB30 and more recently BB30A

    ".... BB30A found on the Synapse. The "A" stands for Asymmetric - the BB30A adds 5mm to the non-drive side of the BB shell for a wider, stiffer base. To accommodate the wider BB shell, the BB30A gets a longer spindle and the non-drive side crankarm angle is changed to maintain the same Q factor and even out ankle clearance on both sides. Cannondale Hollowgram BB30A cranks will work on both BB30 (68mm BB width) and BB30A (73mm bb width) by changing the non-drive side spacers".

    So what you've effectively done is correct, and is the only way to fit a BB30A chainset to your BB30 frame.

    What you haven't got is the 73mm BB shell for that "wider, stiffer base", but unless you're Andre Greipel I doubt you'll notice.

    But if the 5mm spacers on the NDS is troubling you, the only solutions are a BB30 chainset or a BB30A frame.
    Perfect answer. Thankyou

    I was concerned what i did was a bodge. But now it looks like its the correct official bodge.

    Thanks all for your replys
  • jgsijgsi Posts: 5,025
    You could just wait until Cannondale marketing department get bored with offcentre stuff and go back to all nicely symetrical again... much to the head against the wall action in the R & D department.
Sign In or Register to comment.