Crank Arm loosening while riding

macleod113
macleod113 Posts: 560
edited October 2016 in Workshop
Hi All,

Just looking for advice. My FSA left crank arm has started loosening itself throughout my commutes. i can usually get to work but on the return leg its getting so loose it almost falls off (it has done once so far while riding).

I'm wondering if its my speedplay unclipping that is a bit firm and im putting too much welly into unclipping?

I have tried being gentler this week and its not been as loose but just wanted to ask in case there may be anything more sinister at work.

I did lose the crank arm washer when the arm fell off and have since replaced it but there is a small amount of play now when i test it.

Any advice would be greatly appreciated before i give up and ask the LBS.

thanks
Cube Cross 2016
Willier GTR 2014

Comments

  • StillGoing
    StillGoing Posts: 5,211
    FSA Gossamer by any chance? The old type FSA Gossamer was plagued with this problem. A ride buddy had the non-drive side crank arm come off on a particularly fast and busy road. It had been torqued correctly and had the wavy washer in place, but came loose losing the wavy washer in the process. The advice from FSA was to apply a dab of thread loc to the clamp bolt thread and I understand they started supplying the thread loc with cranksets. The new version of the Gossamer doesn't have the problem.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • ugo.santalucia
    ugo.santalucia Posts: 28,310
    yep, a friend had his coming loose at the bottom of the Tourmalet... I botched fixed it and he made it up the mountain, but less than ideal
    left the forum March 2023
  • macleod113
    macleod113 Posts: 560
    Oh yes, its a Gossamer i believe. No thread loc that i can see but i now carry my 8mm long handled allen key just adding to the weight im already carrying.

    Guess i'll be shopping for some now as i cant just drop £100 on a new chainset :-(
    Cube Cross 2016
    Willier GTR 2014
  • lpretro1
    lpretro1 Posts: 237
    Every time it works loose it will be wearing the splines more and more so it will get worse :(
  • The Rookie
    The Rookie Posts: 27,812
    Use some 'bearing lock' on the arm to BB interface, torque up and let it dry, this can sometimes fill in the gaps that the wear from riding loose has created, also a fresh dot if thread lock on the bolt so the play doesn't loosen it. Otherwise it's new cranks time, riding with it loose kills it in no time.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • macleod113
    macleod113 Posts: 560
    Tried some thread loc and after 4 commutes no movement so far. thanks for the advice Philthy3
    Cube Cross 2016
    Willier GTR 2014

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