I went for a bike ride as usual, and after a few kilometers, a loud noise started coming from the bottom bracket area (see video).
The noise only occurs when I’m not pedaling and its intensity seems to depend on the position of the pedals.
Aside from the noise, the bike functions normally. There are no issues at all, even when applying significant torque.
Do you have any idea what might be causing this, and what components I should consider replacing?
Thank you!
Noise from bottom bracket when not pedaling
byu/living_direction_27 inbicycling
by living_direction_27
7 Comments
If the noise only occurs when you stop peddling it’s not the bottom bracket – my guess would be the freehub is unhappy. Is there any feeling that comes with the noise ?
It seems to be in sync with the rotation of your wheels and changed slightly when you moved the cranks. Check your rear hub and freehub, the bearings my be running dry
Yeah there’s something going on with your hub or a wheel rubbing. I would suggest putting in a stand to see if you can duplicate the sound. If it only happens when you’re not peddling, freehub makes the most sense.
Probably rear hub, things can sound in different places to they actually are on a bike. Do you have a workstand you can put it on and replicate it?
Borrow someone else’s back wheel and see if it gets rid of the noise? At least that way you can check if it’s the wheels or not.
It is unlikely that the source is your bottom bracket, even if, as you describe, the sound changes or stops with crank position. They just aren’t the kind of thing that make noise when the pedals aren’t turning. Many people have replaced bottom brackets because they’ve been convinced it’s bad, only to find the problem is elsewhere.
The sound is rhythmic, in time with wheel rotation. Since it stops when you pedal, it must be somewhere in the drivetrain. That rules out the front hub. It also rules out the rear hub bearings since they rotate when you pedal, too.
That leaves the freehub. The fact the sound changes with pedal position doesn’t contradict this conclusion, as moving the freehub relative to the axle could change how parts are interacting.
I had this noise too. Opening up the freehub and cleaning and lubing the ratchets fixed it for me.