Hub or brake drag?

Tom Butcher
Tom Butcher Posts: 3,830
edited July 2013 in Workshop
Mavic ksyrium ES rear wheel, spins freely, no discernible play and brake blocks not set ultra close.

Occasionally when pressing on hard I get a sudden drag/binding from the rear of the bike - it's almost as if someone has grabbed my seatpost or I've given the brakes a squeeze. Can anyone diagnose - is it possible something is momentarily binding in the hub? Brake rub would be my first guess bit it seems more of a sudden slow down than I'd expect from that, I thought possibly the wheel touching the frame too but it doesn't look close.
it's a hard life if you don't weaken.

Comments

  • sungod
    sungod Posts: 17,358
    can't see brake rub causing that much drag, if it were that i'd expect it to be highly repeatable, i.e. on every similar effort

    check qr, dropouts for any signs of damage/wear that could allow the axle to shift in the dropouts

    otherwise i'd strip out the hub and have a good look

    bear in mind it could also be the bb
    my bike - faster than god's and twice as shiny
  • nicklouse
    nicklouse Posts: 50,675
    check the frame for tyre rub marks.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • keef66
    keef66 Posts: 13,123
    Sudden drag like that is characteristic of the tyre hitting the frame due to wheel flex. Is the wheel centred between the stays and is the QR done up properly tight?
  • smidsy
    smidsy Posts: 5,273
    Wheel flex, how dare you! You do know he has Mavic Ksyrium's don't you? :-)
    Yellow is the new Black.
  • keef66
    keef66 Posts: 13,123
    smidsy wrote:
    Wheel flex, how dare you! You do know he has Mavic Ksyrium's don't you? :-)

    He could have thighs like Robert Forstermann. Bet he'd be able to flex a Ksyrium Elite. And / or very tight tyre clearances on his frame
  • Tom Butcher
    Tom Butcher Posts: 3,830
    There's nothing obvious in the hub I can see - had the freehub off anyway. Had the same thing with different bottom brackets and they are square taper so shouldn't be a the shell facing being slightly out. Clearance looks fine but it's only these wheels i've had the problem with so I'm putting it down to the thighs.
    it's a hard life if you don't weaken.
  • sungod
    sungod Posts: 17,358
    put some chalk on the frame (seat stays and chain stays), then when it happens again you've got an easy test if the tyre touched the frame
    my bike - faster than god's and twice as shiny
  • Tom Butcher
    Tom Butcher Posts: 3,830
    Not a bad idea will give that a go and see.
    it's a hard life if you don't weaken.

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