Metallic pinging sounds from cassette - but only when dirty
 

So I'm scratching my head over this one...

When my 11speed Shimano cassette is dirty my bike will emit a metallic pinging/clicking noise. It almost sounds like a creaking sound as if the bike is going to explode at any moment. But the noise only happens when the cassette is dirty. Take rear wheel off the bike, scrub the cassette with a degreaser/brush, put the wheel back on the bike and bingo! Sound/noise is gone.

But ride the bike for a distance (120k? 200k? distance varies) and as the cassette gets dirty the noise start up again. I've had the bike in to the LBS and they couldn't figure it out. At first they thought it was a spoke tension issue. It wasn't.

Anyone have any ideas what it may be? I'd like to get the cassette off the free hub and give it a proper cleaning, but I can't get the lock nut off (the subject of another post over here).

Thanks for your time/reading. Cheers.

My initial reaction was it has to be your spoke tension as well. I just had my rear wheel re-trued and tension checked. Two spokes were loose which caused it to ping under my weight from where it is attached to the hub. Does the sound get louder depending on which side of the bike you are leaning on? For example, on mine the pinging would be louder when I leaned to the right.

Since it's not your spokes, maybe it is your hub and the process of degreasing the cassette cures it temporarily until it gets gunked up again? Have you tried a different chain to eliminate a chain issue?

Who put your bike together? that lock ring sounds like it is either fused on there or way overtightened.

@jadocs the noise does not get louder depending on the side I'm leaning on. The noise DOES get louder and more frequent a) the dirtier the cassette gets and b) as more power is applied to pedals.

I suspect it is the hub too, which is why I want to get the cassette off. I'd like to give the freehub a cleaning, and the cassette a solid cleaning too.

I suspect the lock ring has been over tightened through a combination of the LBS and me checking to make sure a loose cassette is not the issue for the noise.

I once had a cassette that was so clogged up with hardened chain wax that the chain would skip on the two smallest cogs. There was so much buildup between the 11t and 13t that the chain wouldn't seat fully and kept jumping out, causing a clicking sound and slippage. The wax was so hard that I had to chip it out with a small allen key, but after that it was fine.

So maybe if the cassette is super dirty, it's either interfering with chain engagement, or is somehow causing the chain to push up against the ramps for the next larger cog and making noise?

If the cassette is dirty with sand or similar particles, perhaps the sound is those particles getting crunched between the chain and cogs.

Your hub probably does need a good cleaning, but I’m still inclined to believe you have a spoke issue. Have you tried lightly squeezing the spokes in your hand (two at a time)...work your way around the wheel. If you hear the slightest of pings (it will most likely come from where it attaches to the hub) you have a loose spoke.

Edit: misread your reply, still think it’s a spoke though based on the description of the sound.

Thanks @jadocs. I have the cassette off the freehub now and gave the cassette a good cleaning this afternoon. I'll clean the freehub too and re-assemble everything tomorrow. I'll take a look at the spokes too. Thanks.

I was thinking last night about this. Take a close look at where the spokes go into the rear hub. It is entirely possible that the degreasing with cassette on temporarily cleaned the crud around the spokes where they go into the hub ...which could explain why the noise goes away and comes back when dirty.

I have found that the cassettes that have the larger cogs mounted on aluminum "carriers" can get noisier with time. I think it's because the carrier moves around a bit on the cassette body and when it shifts it makes a crunchy ping. In your case you cure it by removing, cleaning, and retightening the cassette... but once it starts moving again it won't stop.

Try cleaning all the pieces of the cassette again and then reassemble with a layer of grease on the cassette body and between the aluminum carriers. It won't stop the movement, but at least it won't be as noisy about it.

@Jeff Wills well you may be right. I had the cassette of the free hub and gave it a good scrubbing last night, then let it air dry and put it back on the freehub today. Only I put the cassette back on the freehub WITHOUT any grease. I was uncertain if I should put grease on the freehub or not. I did a lot of googling around and it seemed like the verdict was 50/50 on whether to grease or not to grease. The only grease I put on the freehub was a little bit on the lock ring.

And the cassette was noisier than ever...Frustrating as all get out.

Thanks for the suggestion to put a layer of grease on the freehub and aluminum carriers though. I hadn't thought of that.

The bit about the noise on the carriers. Is this an issue with the carrier that I need to worry about? Thank you.

I've not personally ever heard of any problems with cassette carriers/spiders, but along that theme, maybe some of the rivets that hold the cogs on have become loose? That might cause some creaking issues. I know chainrings can creak if the bolts come loose, so maybe cassettes can too.

There's just a lot going on back there and there are a lot of potential noise sources (i.e. many mechanical interfaces, bearings, pivots, spoke-to-rim and spoke-to-hub junctions, etc). Maybe the freehub is a little loose or something as well. Maybe the cleaning doesn't really do anything but the act of removing and reinstalling the wheel re-seats the axle or bearings in some way that makes the noise go away for a while.

How many miles on the cassette? How about the chain?

Seems I read somewhere that shimano 11speed cassettes required a spacer behind them. You might check into this.

For me it's most noticeable when starting from a dead stop in a low gear (which, naturally, are the cogs that are on an aluminum carrier). One or two strong pedal strokes and the cassette goes "Squark!" and then quiets down. I've never noticed that they wear out any faster if they make this noise.

I've dealt with this issue a couple times by ditching the expensive cassette and reverting to cheaper cassettes with all-steel cogs. This gets me in the weight-weenie side of my brain, but if I wanted to reduce weight I'd be on a diet. Good golly, what a potbelly...

Whelp...Mrs. NoWhammies and I were going away for five days of no riding. So I dropped my bike off with a Mrs. NoWhammies friend, who also owned a bike shop for many years, to have a look at my bike. Turns out a while bunch of work was needed/done...

Bearings in the rear hub - replaced and regreased
Bearings in the bottom bracket - replaces and regreased

And some other work not needed to be mentioned here. So tonight, once I get back home from work, I'll take the bike out and go for a spin. Based on all the work that was done on the bike though, I'm optimistic the noise is now gone.

@2manybikes there is approx 10,000km on the rear cassette and there there was over 5,300km on the chain.

@Baboo Next time I have the cassette off (which will likely be when I replace it next) I'll look for the spacer.

I think you have found your problem, No? Can't believe you didn't replace this stuff the first thing.
Tell Mrs. NoWhammies I have a bike too, and can drop it off with her.

Many of the other forum members would likely agree, that the chain and cassette would be a problem with the km totals on those parts.

No 11 speed cassette needs a spacer. Most Shimano 10-speed cassettes need a spacer for use on most any freehub. All non-11-speed cassettes need a spacer on Mavic road wheels or any 11-speed free hub.

The cassette should not be moving around on the freehub body. If it is, the lockring isn't tight enough. I doubt most people torque to the full 40 N*m.

Thanks for the clarification I must have read it wrong, not surprising though I’m wrong a lot.

@trailangel yes, the problem has been found and solved. Went for a ride last night and the bike was quiet. Finally! (although now I've probably cursed myself...)

How far did you go?