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Loose forks

notsobluenotsoblue Posts: 5,838
edited September 2010 in Workshop
Hi chaps,

Got a question about the headset/forks on my new PX SL Carbon. There seems to be a bit of play in them (when using the front brake and rocking back and forth). I followed this guide: http://www.youtube.com/watch?v=3OnmM9EjeiE , but there still seems to be some play. I've loosened the stem bolts, undone the top cap, and lightly bounced the front of the bike to bed the bearings, tightened the top cap and stem bolts. Can anything recommend anything else to try? There isn't a disturbing amount of play, perhaps about a millimeter or so. But its noticeable when breaking. Am I being too sensitive or is there something wrong here?

Cheers,

NSB

Posts

  • alfabluealfablue Posts: 8,497
    Is there a sufficient gap between the insert in the steerer tube (the bung, equivalent of star nut) and the top of the steerer? If this is too small then the top cap tightens down on this rather than properly tensioning the bearings.

    This happened to me when I swapped out the original spacers for some carbon ones of slightly different size, but also there is the possibility that the bung may have slipped upwards.
  • notsoblue wrote:
    Hi chaps,

    Got a question about the headset/forks on my new PX SL Carbon. There seems to be a bit of play in them (when using the front brake and rocking back and forth). I followed this guide: http://www.youtube.com/watch?v=3OnmM9EjeiE , but there still seems to be some play. I've loosened the stem bolts, undone the top cap, and lightly bounced the front of the bike to bed the bearings, tightened the top cap and stem bolts. Can anything recommend anything else to try? There isn't a disturbing amount of play, perhaps about a millimeter or so. But its noticeable when breaking. Am I being too sensitive or is there something wrong here?

    Cheers,

    NSB

    1 mm is a lot of play...

    Cap bolt should be tihghtened last and undone first... then undo the stem bolts, push the stem down with your hand, tighten the bolts and recheck. The steerer should do its job with no play but no resistance either. Once you are happy, tighten the cap screw, maybe with a bit of thread lock to avoid coming loose.
    The cap should not be determining the amount of play, infact some bikes don't even have a screw on the cap... it's just there for extra security.
  • alfabluealfablue Posts: 8,497
    notsoblue wrote:
    Hi chaps,

    Got a question about the headset/forks on my new PX SL Carbon. There seems to be a bit of play in them (when using the front brake and rocking back and forth). I followed this guide: http://www.youtube.com/watch?v=3OnmM9EjeiE , but there still seems to be some play. I've loosened the stem bolts, undone the top cap, and lightly bounced the front of the bike to bed the bearings, tightened the top cap and stem bolts. Can anything recommend anything else to try? There isn't a disturbing amount of play, perhaps about a millimeter or so. But its noticeable when breaking. Am I being too sensitive or is there something wrong here?

    Cheers,

    NSB

    1 mm is a lot of play...

    Cap bolt should be tihghtened last and undone first... then undo the stem bolts, push the stem down with your hand, tighten the bolts and recheck. The steerer should do its job with no play but no resistance either. Once you are happy, tighten the cap screw, maybe with a bit of thread lock to avoid coming loose.
    The cap should not be determining the amount of play, infact some bikes don't even have a screw on the cap... it's just there for extra security.
    I'm not sure I agree with your method, it is far easier to tension the bearings using the top cap. I agree, AFTER the bearing is tensioned, and then the stem bolts tightened, the top cap could be removed if you so desired (but there is no point).

    Pushing the stem down and tightening stem bolts as the method is potentially unreliable, for instsance you may inadvertantly release the pressure as you tighten the stem bolts. I would say cap bolt should be tightened first, before stem bolts, as would the vast majority of others.

    Or have I misunderstood your post?

    Back to OP - you are looking for this sort of space between steerer and top cap, and bung/expansion plug and end of steerer:
    fork11.jpgtns06.jpgcomp-plug_1.jpg
    see http://www.parktool.com/repair/readhowto.asp?id=67
  • WIth your method I find that once I tighten the stem bolts, the tension is different and the steerer does not run smoothly
  • notsobluenotsoblue Posts: 5,838
    Well I passed by a LBS on the way home, and they simply repeated what I had tried before - loosening the stem bolts, then the top cap, bit of a wiggle, tightened the top cap, and tightened the stem bolts again. And oddly that did the trick. Perfect fit now and very happy with the ride. :)

    Just as a side note, I can't fault the bike build by PX. Love the bike!
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