Another BB30a

dboden
dboden Posts: 349
edited August 2016 in Workshop
Could anyone please confirm / help with a technical query have.


ok, I have a 2014 Cannondale Synapse.. I did not want to use BB30a BB
So I installed an FSA adapter to be able to use a threaded 24mm BBracket..
I obviously cannot use a Shimano chain set, as this is only for 68mm width BB. (I initially thought I could!! doh)

I know the SRAM bottom bracket is for 68/73mm width.
So can I just install a SRAM GXP BBracket along with a SRAM Force 22 chainset? (is the spindle/Axle long enough?)

Has anybody else done this?

Thanks Dave

Comments

  • svetty
    svetty Posts: 1,904
    You can use any normal Shimano hollowtech chainset. The FSA adaptor reduces the spindle size down from the native BB30A spindle diameter of 30mm to the Shimano 24mm spindle diameter. The only issue is that you might need shims to adjust the bearing axial preload and to enable adjustment of the chainline (Shimano standard is 43.5mm).
    FFS! Harden up and grow a pair :D
  • dboden
    dboden Posts: 349
    If you can use any Shimano hollow tech chain set, surely you need a different bottom bracket, as with standard bottom bracket, the spindle would be 5mm too short???
  • sungod
    sungod Posts: 17,156
    the bb shell in a threaded system then has the extra depth of the cups added to it, unlike bb30 where the bearings fit inside the shell

    i.e. a hollowtech crankset spindle is longer than a bb30 one
    my bike - faster than god's and twice as shiny
  • dboden
    dboden Posts: 349
    hollowtech crankset spindle is to fit 68mm + BB - BB30a is 73mm + BB

    I know this because I had a shimano Ultegra 6800 fitted to it... It turns out the spindle was 5mm shorter than it should be.
    It was running sweet.. but then the non drive side crank arm came off!! it had completely sheared the splines smooth.

    I now have the adapter in, as an option.. but am looking for a solution.
  • sungod
    sungod Posts: 17,156
    sorry, i missed the 'a', yes 73mm vs. 68

    to stick with shimano cranks, i think there are other adaptors you can use, for instance c-bear does this one...

    https://www.c-bear.com/en/products/bott ... face-rotor

    ...but best to check with them to confirm

    edit, also... http://kogelbearings.mysimplestore.com/ ... ano-cranks

    pricey though
    my bike - faster than god's and twice as shiny
  • svetty
    svetty Posts: 1,904
    It sounds as if you are trying to use ordinary external 24mm bearings on a 73mm shell? Clearly this won't work - as you say the spindle will be too short. You need to use the correct adaptor. Wheels Manufacturing are well regarded. You will need to shim the cranks to adjust the pre-load as previously stated

    http://wheelsmfg.com/bbright-adapter-fo ... ranks.html
    FFS! Harden up and grow a pair :D

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