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Help ! Is there a mechanic in the house ?

datpat64datpat64 Posts: 85
edited February 2011 in Road beginners
Or at least someone to glean some advice from.

I've always had Shimano BB30 bottom brackets and Mega Exo, but just managed to get a real deal on an FSA Gossamer Compact crank set. It requires an ISIS bottom bracket rather than a BB30 but my question is what axle length ?

I looked at a couple of sites regarding chain line and thought a 108 mm would do. Have fitted that and i can't get front derailleur to work. Had a quick word with LBS and they reckon that BB30 adds almost 20mm (10mm per side) to a chainline and thus 108 should have been more like 118mm (maximum you can get ISIS in).

Anyone any ideas or do I sell the FSA and get a new crankset for BB30 ?



  • crakercraker Posts: 1,739
    No idea but I'll have your FSA off you when you give up on it.

  • Monty DogMonty Dog Posts: 20,614
    Standard ISIS road double is 108mm for 68mm BB shell - but by the sounds you're fitting it to a BB30 shell which is a standard 68mm shell and therefore should still work OK. Are you sure your frame is BB30 not BB86 or BB90? What make is your frame?
    Make mine an Italian, with Campagnolo on the side..
  • Shimano don't do BB30.

    *Edited to change incorrect info about megaexo, oops!
  • Frame is a Specialized Allez and I must admit thought I'd done the maths right when I looked at the chain line .

  • they were SHimano Hollowtech BB I used before if that makes any sense ! Wish I'd stayed with them now !
  • Monty DogMonty Dog Posts: 20,614
    Allez has standard 68mm British threaded BB shell - there's no reason why your 108mm ISIS BB shouldn't work - the inner chainring I presume clears the chainstay by about 3mm? Sounds like there's a problem with your front mech set up. Talking about BB30 appears to be completely spurious to your requirement.
    Make mine an Italian, with Campagnolo on the side..
  • Monty

    Thanks for the post and sorry for slow response. I I adjusted front mech and tightened cables and hey presto we now have a working derailleur. There's a slight catch when in cross chain gears, but as I don't use these it hasn't been an issue thanks for the advice and you've saved me another bottom bracket !
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