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My MTB, having not received much TLC lately, was making a lot of squeaks and noises. After a long-overdue clean-up and lubrication of the drivetrain, most have gone away.

However there's something still making clicking (?) noises, and it seems to come from the bottom bracket area.

It only happens when I pedal, regardless if I use a lot of force or not, but not for super-light action - like pedalling by hand, with the bike on a stand.

See (and hear) this video.

Any suggestions to what may be causing this?

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  • My top guess, based on the video, is crumbling ball-bearings in your bottom bracket. Could also be bad chain links: check the chain links for 'kinks' or individual links that bind and do not pivot freely. If it's chain related, it should present as more of a rhythmic cadence as the bad link(s) make their way around the drivetrain. – Matt Goodman Sep 28 '20 at 12:13
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My first suspicion is the chain hitting the front derailleur cage. The clicking is fairly loud and occurs continuously whenever you pedal. If the bottom bracket bearings were damaged you would feel it through the cranks rather than hearing it and there would be clicks once per crank rotation.

It's also possible that you have chainsuck going on. A worn chainring can hold on to chain links past the point where they should disengage, then they pop off the chainring teeth with a click.

Put the bike in a workstand (or have a friend hold the back wheel of the ground), pedal manually and inspect the crank area to see where the noise is coming from. Try different gear combination to see if that makes a difference.

You can also check the bottom bracket bearings - turn the crank by hand and feel for clicks or 'notchiness'. Push and pull the cranks to check for any play in the bearings.

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  • Great suggestions! I noticed that pedalling "by hand" (bike on stand) doesn't produce clicking (This seems relevant, I updated the Q) Unless there's a lot of flex even under moderate tension (as compared to the stationary situation) I would rule out the chain hitting the front cage. Maybe chainsuck is more prone to happen under tension. I will next try to take the chain out of the equation by derailing it off the front sprockets and just pedalling freely. Maybe just my weight on the pedals is enough to trigger the clicking. Will update findings. – Cristian Diaconescu Sep 28 '20 at 21:25
  • Under pressure, is it possible to move the right-hand crank backwards/forwards slightly whilst holding the other crank fixed? This fault was common with (very) vintage cottered cranks and could still be happening if you have any problems in the bottom bracket/crank end of things. – Jeremy Boden Sep 29 '20 at 15:14

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