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Cranks coming loose

tjdixon911tjdixon911 Posts: 110
edited August 2010 in MTB workshop & tech
My cranks keep coming loose, does anyone know what can be causing this?

I'm running Truvaiiv FireX Cranckset (Double converted to single) with e*thirteen chain guide, I have to tighten them up every 10miles or so....

Any help much appreciated.

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    what fitting?

    splines/square taper or....
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The RookieThe Rookie Posts: 27,802
    I'll guess at Isis.........

    How tight are you doing up the bolts will be the next Q, so you may as well answer that as well!

    Simon
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • tjdixon911tjdixon911 Posts: 110
    nicklouse wrote:
    what fitting?

    splines/square taper or....

    Not Sure, its got two bolts, an inner one and an outer one, (self extracting?) for some reason the inner one is the one that comes loose, the outer remains tight.

    I am tightening them fairly tight!
  • nicklousenicklouse Posts: 50,675 Lives Here
    so external bearings.

    heave on the inner and make sure the outer is tight.

    but you may have already killed the splines.

    you need a long allen key.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • supersonicsupersonic Posts: 82,708 Lives Here
    Nick, i think he means a nrmal crank bolt and the extractor ring, my guess is an ISIS or ST as you first thought.
  • nicklousenicklouse Posts: 50,675 Lives Here
    but they dont have the lock ring. just the firex on the external.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The RookieThe Rookie Posts: 27,802
    Photo's I think......

    Simon
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • benpinnickbenpinnick Posts: 4,148
    nicklouse wrote:
    but they dont have the lock ring. just the firex on the external.

    He's right you know... Sounds like external BB. If they keep coming loose unfortunately they are possibly already toast. No amount of string arm allen key usage will keep them on. Worth trying with some loctite first though. Could just be poor thread match between the axle and the retention bolt.

    A small bottle of Loctite 243 might do the job.
    A Flock of Birds
    + some other bikes.
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