Boardman Pro Carbon SLR - Crankset Problem

rcronin99
rcronin99 Posts: 4
in Workshop
Morning Everyone,

I hope everyone is well and any help on this topic will be much appreciated.

I purchased a second hand carbon road bike last year after my original bike was pinched a week before I underwent a charity cycle up Aple d'Huez and have had a few problems with the crankset.

I was cycling uphill and felt a strange sensation ending with the LH crank arm coming loose having stripped the lower quarter of the spline teeth.

I have noticed that the bike is fitted with a 73 mm overall length PF30 bottom bracket with a FSA PF30 24 Reducer and Ultegra FC R8000 crankset.

My research tells me that a 68 mm bottom bracket is needed for all road setups and im wondering if this has caused the problem.

My questions are; how can this be remedied as only one thickness reducer is on the market and why this road bike was manufactured with a 73 mm bottom bracket seemingly incompatible with road groupsets.

Regards,

Rob

Comments

  • Ben6899
    Ben6899 Posts: 9,686
    Morning Rob,

    The reducer is to allow you to install a crank spindle of 24mm (Shimano's standard) in the 30mm bearings (used in the PF30 bottom bracket installation).

    68mm is a bit of a red herring, nowadays. The traditional British Standard bottom bracket is 68mm, but there are so many (too many) bottom bracket "standards" nowadays.

    PF30 is Press Fit and sits in a bottom bracket shell which is 68mm, 73mm or 83mm.

    So all things equal, your bike and BB are fine. You just need a new chainset (with 24mm spindle and keeping the reducers) or with 30mm (make sure it's for PF30 and not BB30, I think they're different widths) and not using the reducers.

    I hope that helps!
    Ben

    Bikes: Donhou DSS4 Custom | Condor Italia RC | Gios Megalite | Dolan Preffisio | Giant Bowery '76
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  • rcronin99
    rcronin99 Posts: 4
    Thanks for the clarification Ben. I have now measures things up again and the shell width is 68 mm and then 73 mm including the lips of the press fit bottom bracket.

    The bottom bracket is a SRAM PressFit 30 Alloy Bottom Bracket and the reducer is an FSA PF30 24 Reducer Road (EE085).

    With this combination the LH crank arm doesn't close up enough and does not let the security pin go through the hole in the hollowtech axel.

    I will try an FSA BB392EVO 24 Reducer (EE084) to see if this is compatible.

    Thanks again,

    Rob

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