Weird rumble, silent pop when pedaling - Solved
 

This one is hard to describe. I thought it was maybe the pedal bearings or some play in the pedals so I took them out this weekend, new grease, no play but this is still in there.

When I pedal sometimes I can feel it on my feet, some rumbling or pop but its silent I can only feel it. Sometimes its on one foot, sometimes the other and only at certain times, sometimes its smooth. I am thinking maybe crank bearings? The cranks are super record with ceramic bearings that I got from someone here in the forums. How long do ceramic bearings last? Could it be something else?

I would switch pedals and see if the issue persists. It's a process of elimination these things. Sucks.

Could it be slightly loose bb, chainring bolts, etc?

Does it happen when you wear sneakers?

The notchiness of bad bearings is usually too small to notice when riding.

A stronger possibility is a worn chain and/or sprockets, and or chainrings. When one (or more) of these are worn, the mismatch between the pitch of the chain and sprocket can cause a vibration as the teeth engage with the rollers. The larger magnitudes of the forces involved will make any vibrations caused larger and easier to notice than bearing notchiness. These vibrations will also vary between different sprockets and different chainrings, depending on the degree of wear difference between chain and sprocket/chainring.

In particular, chainrings wear can wear unevenly, with more wear on the teeth that are engaged during the power portion of the pedal stroke. There can be a very distinct 'jerkiness' (for lack of a better term) felt in the pedals as the chain transitions from the more worn to the less worn portions of the chainring.

@coloneljloyd - I need to do that and should have been what I did this weekend instead of re greasing the bearings. Will start there for sure.

@parris - thought that too, the campy cups look tight enough but might need to remove the crank and really check. I know that the C clip was coming out last week and I just put it back in. I checked chainring bolts by hand they all seem to be there, also chainrings not moving around.

@jtakeda - Have to try this. I did try to not clip in and still felt it.

@Mark McM - Could be chainring wear but the chainrings don't look like they have many miles to be honest. Definitely not chain or cassette wear as they both have less than 500 miles.

What rear wheel? Mavic krysirium by chance? Could be BB, crank off(remember clip on RH cup, you DO have a clip on RH cup, yes?)...spin in hand...feel smooth or not?

If it's crank-rpm related my money is on the bottom bracket bearings or the interface between the two side of the crank.

dave

wheels are hunt (so some sort of taiwan generic hub).

clip is on the RH cup. I won't have access to tools for a couple of weeks so would be able to take crank off but I will do that. I know that crank, without the chain on it spins like butter. I remember when installing, the bearings felt AMAZING.


@David Kirk - it does seem to be rpm based, I think. and I feel usually at a certain angle on the crankset.


edit- also thank you to everyone so far for the help and time!

I'm thinking chain/cassette/link/chainrings/chainline. Is the bike new to you? What kind of chainrings, chain, cassette, and chain link (if any)? How does the chainline look? Is the derailleur hanger straight?

only thing is I don't think it used to do it when I put it together. Bike is new to me but I put all the stuff together.

Its got a sram cassette, mid cage athena RD, KMC 11sp chain. Chainrings are super record.

Everything is new but the chainrings.

That's quite a mix of vendors. Technically it should work, but will it work as well as all Campagnolo?

Is the noise/feeling different in different gears or with different pedaling loads?

dave

well its mostly campagnolo. Only thing that is not campy is the sram cassette (which I am not a fan off, ultegra cassete is much better, quieter, more precise) and KMC chain which I exclusively use on all my bikes and never had a problem.

@davidkirk - there is no noise I hear. The feeling is the same on all gears but lighter gears I don't feel it as much because light pedaling. Definitely kicks in when I pedal heavier.

It sounds like a worn chain or that the BB bearings are toast. It's fast and free to pull the crank out and stick your finger into the BB bearing and slowing rotate it.....if it's anything but butter smooth it's toast.

dave