BB30 Front Derailleur Issues

Discuss light weight issues concerning road bikes & parts.
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by mortirollover

Have just replaced my Ultra Torque cransket with a Hollowgram BB30 on an SLR01 BMC Team Machine. My Campy front derailleur now cant get inboard enough to stop from rubbing the chain (the FD body hits the seat tube) the only cure is to raise it up an inch above the outer ring which is cludgy.
Anyone had a similar problem? seems kind of a design flaw that i would get a BB30 then need to space it out to get the FD to work.

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by motorthings

i have a hard time imagining how that would happen...can you post a photo?

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by mortirollover

Yup will try and post tonight. Its a compact crankset (36/50) maybe the front derailleur cant go lower than you'd need it on a 53 tooth. BMC did change to the wider BB86 for this model this year..........

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by btompkins0112

Sounds like you are missing a spacer on the drive side of the crank.....

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by BeeBee30

I had this problem on a SystemSix with Hollogram cranks, it only happened with a certain make and model of front mech which i can't remember but when I changed to a different brand the problem was eliminated.
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by thisisatest

two things going on here.
one is that campy front derailleurs dont have much room to be adjusted inward from what is exactly prescribed.
the other thing is that, and it's been this way since the beginning of SI cranks' time, Cannondale cranks have a chainline measurement that is smaller than anyone else, beyond what is ideal. why else would cannondale have all the issues with srm spiders rubbing here and there, but no other cranks have issues, even on otherwise identical frames?
there is other evidence to support this, but i'll leave it for another time. ideally, cannondale would change their spindle length to 108mm or so. in the meantime, i would recommend an SRM specific left bearing shield. it's essentially thinner, so the crank shifts to the right.
any extra spacers behind the spider will NOT move the chainrings to the right, unless you are crushing the bearings at the same time.

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by mortirollover

Thanks all for the responses. Yup originally had only a single spacer in there (manual says thats all you need for road). Three spacers did push it out to the right giving more room for the front deraillur to clear the chain before hitting the seat tube. However appreciate the comment that this has probably jacked up bearing pre load some. Maybe shouldnt have gone for the Hollowgram, guess I saved 100grams, added an unnoticable amount of stiffness but added a lot of mechanical drag?????

by Weenie

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