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    Bicycle Motocross

    After every ride my cranks do this and everything is tightened beforehand

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    9 Comments

    2. idkfadoomcheat on

      Yor bolts shouldn’t be going loose like that, you should probably put some loctite on the threads of the bolts. That should help a lot

    3. quantumfox20 on

      The same thing happens to me, I just locktite’ed the bolt in and carry a hex key with me when I ride just in case. Not a permanent solution but it’s by far the cheapest.

    4. Gurnasaurus on

      Had this exact setup on a jump bike I had, did identical but not this badly. I’d recommend loctiting(sp) the bolts, and making sure (as I can’t see in the video) your preload bolts are in there and tight enough. These two things fixed it for me. The smaller locking bolts had to go pretty tight for me too, be careful of stripping them out of frustration tho lol.

    5. throwawaypi123 on

      Problem with 8 spline cranks are if you rode with your cranks loose at any point you could have warped the interface it sits on. No amount of tightening will do anything.

      Check for play when you put pressure on the cranks and wiggle them about.

      You can either replace crank arms or spindle. Otherwise the bodge is to cut some coke can and shim the crank.

    6. Another_Meow_Machine on

      In addition to Loc-Tite, make sure you’re torquing them down right. Cranks usually need a LOT of force, like cheater-bar sorta force sometimes

    7. Awkward_Importance49 on

      You need to tighten the two spindle end bolts before you tighten the crank arm bolts. Also, before you tighten anything, get the drive side crank on the spindle and with a wooden mallet give it some firm taps to make sure it is fully seated.

      Then put the other crank arm on and tap that home with a mallet too. Not hard, just enough to make sure you seat everything home and there is no slop. A little bit of slop can lead to everything coming loose.

      Following that, you should tighten both Spindle bolts to the point where there is just the start of stiffness in the crank rotation. Just a tiny bit. Riding will loosen that back up again.

      Then tighten the crank arm bolts after the spinlde bolts.

      If you use a threadlocker, use a blue gummy anaerobic threadlocker eg…

      https://www.loctiteproducts.com/en/products/specialty-products/specialty/loctite_threadlockerblue242.html

      And clean the bolt threads first with white spirit, and down the spindle holes with a cotton bud dipped in white spirit to dissolve oil and grease in there. Clean all the gunk out, then add threadlock, then tighten them home.

      I was having this problem with a set of Mission Transit 8 Spline cranks, but having refitted them and doing the above ^ they have remained tight and secure ever since.

    9. matrixgang on

      I’ve built so many bmxs and I’ve had this issue once. This shouldn’t be possible unless you are missing spacers and/or the bolt is unscrewing itself while you ride.

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