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I'm having an issue with a creaking sound on a brand new bike (see video below). It seems to happen after 30+ min rides, you can faintly hear it when the pedals are spun backwards but this usually causes the sound to go away for 20ish minutes but will come back.

  • Sound happens at specific rotation point in crank
  • This happens on both road and trainer rides.
  • Its been to 2 different lbs and have not been able to find anything

BB is praxis M30 BB86

Any idea's on what could be causing this sound? I was told that it would eventually subside but after a couple of long ride it's starting to get to me.

video of the issue

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  • Welcome to the BB86 club, I've had a similar issue, a clicking noise at one point in the crank rotation, occurring after longer rides in warm conditions. My mechanic said that it comes and goes because of tolerances and material stretching (especially in summer). bicycles.stackexchange.com/questions/89316/… In my case, I had the bike shop re-install the bottom bracket, by the looks with lots of grease and the issue has been gone since then. Not sure if permanent but for a few longer rides, already.
    – DoNuT
    Jul 10, 2023 at 6:01

1 Answer 1

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That is quite a significant noise from the bike. Obviously abnormal. The best piece of advise I can give you is that as a new bike, presumably under warranty, the bike shop or online retailer should be helping you solve this issue. I would take the bike back there to them. Have a way to show them the video you linked to in your question since the noise is not always reproducible. Praxis has a 2 year warranty on their products. Working with the bike retailer, contact should be made with Praxis regarding the noise and possible fixes, up to and including replacement (at no cost to you).

Here is the link to the Praxis M30 road crank installation guide that also contains the details of their warranty.

A few things to try prior to the bike shop. Inspect the BB area, making sure there is only one dust cover on each side. Also determine that the drive side has a wave washer between the dust cover and crank. If all seems in place then check that the crankarm fixing bolt in the left crankarm is adequately torqued. The spec torque range for this bolt is 48-52 Newton-meters. That is a significant amount of torque that may be difficult for the average person to achieve with a simple "L" shaped Allen wrench. Especially one that is short. A socket with an 8mm hex head on it used with the appropriate ratchet is probably best. That will also fit on the torque wrench that should be used for certainty.

You can also check the torque of the chainrings bolts (should be between 8-10Nm). I don't believe the chainrings are the source of the noise because there isn't any pressure on the cranks when the sound is heard. It sure seems like the sound is related to a problem in the bottom bracket bearing system.

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