Pinging or knocking heard from bottom bracket
 

Hey All, Without taking the bike apart, I was hoping to figure out what a knocking or pinging sound is due to. It seems like it's coming from the bottom bracket. It happens at the same point in my peddle cycle (although that point has changed over time). I suspect something is loose like a ball bearing or something is cracked.. It only happens when I'm peddling and there is load on the chain. Any ideas? Thanks!

Audio: https://vocaroo.com/i/s1bidFnmnnGa

Put a new bb in and see if it goes away.

If you have another bike you might swap pedals with it temporarily. Sometimes when under a load, a bad bearing in a pedal can make that same feeling. Very hard to tell when not under load, so don't just think because they spin smoothly all is well.

Always do the easy and cheap thing first.

Check the bolts. Make sure nothing is loose. Tighten or torque as needed.

If nothing is loose then proceed to more difficult/expensive solutions.


-Tim-

I had a similar issue just last week, a ticking sound at the same point of the pedal cycle that I only could hear with weight on the cycle. I couldn't replicate it on the stand. If you have an alloy frame, the sound can travel and it's difficult to tell exactly where it's coming from. I took mine to the shop to possibly have the bottom bracket replaced, and it turned out the sound was coming from the seatpost. The tech cleaned the post, put some goop (I forgot what he said it was) on it and tightened her down....problem solved. While googling around trying to figure it out on my own, as the poster above said, pedal issues can cause this as well.

check chainring bolts

A knocking sound can also come from a freewheel. I just replaced a bottom bracket and still had some knocking on some speeds.

If your bike has a kickstand that's the first thing I would look at. If your BB is just a tad bit loose the load on the chain may be what's bringing the left crank arm in to where it hits.

Ditto the seatpost/saddle clamp suggestion. If the noise goes away when you stand while pedaling, that's it.

I'm ashamed to admit how long it took me to find that on my bike once, after replacing the bottom bracket too. It's amazing how noises telegraph in a bike frame.

Also, make sure the pedal threads (into the crank) are greased and tight. Lots of crank noises come from pedal threads.