Can't work this one out....
I've got a Truvariv Firex chainset, but the non drive crank arm keeps working loose. I've tried loctite on both the inner and outer locking bolt, but it keeps working loose enough to allow play in the crank arm (and hence the whole chainset) after a couple of rides.
Anything I am obviously doing wrong?
the outer nut is there as a self-extractor. as you undo the inner screw it pushes back against the nut and pushes the crank off the bb axle. it has no 'locking' function.
you need to do up the bolt ba5tard tight, but unfortunately, if the arm has come loose on you a few times, you may as well save yourself a load of time and energy, and just go and buy some shimano right now. the splines are likely worn, and theres unlikely to be any coming back from it now. sorry. IME.
Aha! I had (have?) the exact same problem on the exact same crank!
Are you running spacers between the bottom bracket shell and the external bearings?
I found I had to play around with the spacing. Took me ages to work out why it kept coming loose.
Originally ran this chainset on my FSR with no problems, switched it to a Stumpjumper hardtail and it worked loose during a race.
Tightened it up afterwards and rode it without incident for about a month.Then I could feel play when I stood out of the saddle. Tightened it REALLY tight and loctited it. A week later it started to work loose again.
At which point I took the whole BB assembly to bits, got out the micrometer and all the BB spacers I owned and set about the perfect set up.
So far, two months down the line I've had no further issues.
I'd make sure the crank is as far on the splined axle as it is possible to get it then threadlok the bolt and tighten it up like your life depends on it.
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