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Raceface bb problem - chainring movement

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  • 27-06-2012 4:45pm
    #1
    joxerjohn
    Registered Users Posts: 396 ✭✭


    I fitted a Raceface x-type cadence bb and chrankset to my bike which previously had a square taper bb fitted. After installation everything looked fine with cranks and chain rings nice and snug and rotating freely and true. After a few rides I noticed some in / out movement the chainring about 2-3 mm. I re-fitted it which fixed the problem. After another few rides 300 k or so the problem has re occurred again.

    The crank bolt is not loose and I don't think the spline is damaged but I am unsure how I might correct the problem. I also have not re faced the bb shell.

    Anyone got any ideas on possible cause and solutions and suggested links that I might consult. Would replacing the bb for a better one help ?

    Thanks
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    #2
    joxerjohn
    Registered Users Posts: 396 ✭✭joxerjohn


    Seems all are as puzzled as me on this one as I have had no comments or suggestions . Anyway here an update which hopefully will help others who may encounter this problem.

    The critical issue on fitting external type bottom brackets seems to be the BB shell width. The installation instructions talk about having to "face" the bb shell. This procedure requires a special tool and is really a specialist job. It also may not be necessary as it will have been done in the factory when the frame is being made.

    However my bike previously had a cartridge style BB fitted and so I decided to check the bb shell width. When I removed the external cups I had fitted I noticed that the faces of the BB had the original paint on them. When I measured the shell with a vernier calipers it came out at 68.8mm. The tolerance for this crankset in the instructions was between 67.25 - 68.25 mm so mine was slighty too big.

    I removed the excess paint from the BB shell faces with a blade and a light sanding to expsoe the metal faces (as shown in another Youtube clip) and then remeasured. The bb shell width came down to about 68.1mm i.e within tolerance. I refitted the external cups and the crankset with the spacers and the movement problem was resolved.

    Hopefully this has solved my problem, if the movement in the chainring does re occur this will mean that I have previously damaged the splines by not ensuring that the tolerance on the bb shell was correct in the first place.

    The lesson here is that if you are upgrading from a cartridge style bb to an external bb you need to ensure that the the bb faces are clear of any paint and that the width of the shell is within tolerance for the crankset you are fitting otherwise you will have problems. If you find that the cleaned bb shell is to wide you will need to have the facing job done using the facing tool by a competent bike shop I suggest.

    Good luck !


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    #3
    joxerjohn
    Registered Users Posts: 396 ✭✭joxerjohn


    Well I am afraid that the in and out moovement on the drive side returned on this crankset so I gave up in disgust and removed the whole Crankset and BB. I then tried to get the BB refaced but with no success, I tried three highly recommended cycle shops and one engineering shop in Dublin but all could not assist as they either did not have a facing tool or the one they had was broken. Not much good to me so I sourced an Ultegra cranket and a new Ultegra BB cup set.

    The design of the Ultegra is so much more forgiving and when I fitted it worked flawlessly on the bike and really highlighted the inferior and fussy design of the Raceface Crankset. Also the Raceface BB cups had totally seized after 500 km and the spacers were deformed and pretty beat up.

    All in all my advice would be avoid Raceface like the plague and go for the Shimano design if you are upgrading to an external bearing I would say that the Tiagra would also work very well. The Shimano installation instructions are straight forward with no critical warnings re facing and vetsry tight tolerance etc. I design where the non drive side crank arm position is essentially adjustable works really well.

    Amazing really how poor a crankset with a RRP of €200+ worked out to be.

    Be warned !!! and be advised !!!

    Good luck form Cranksville


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    #4
    gman2k
    Registered Users Posts: 4,076 ✭✭✭gman2k


    I presume you had the spacers set up correctly for the 68mm shell?


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    #5
    joxerjohn
    Registered Users Posts: 396 ✭✭joxerjohn


    The spacers really allowedd chain line adjustment and shouldn't have caused a problem no matter how they were put in. As it happens they were set as recommended.

    As I say in contrast no spacers needed with Shimano much simpler and better design IMO.


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