WillyWonkaBike

Hi,

I have noticed that my transmission makes a strange noise, something I would describe as grinding. It is similar to the sound produced by air bubbles under water. I have included a link to a youtube video where I have recorded the noise: https ://youtu.be/q_5lLROkJdk (just copy the previous link and remove the white space after "https")

In the video you will see that I am backpedaling, but the noise is also present when normal pedaling (forward). I think it is mostly present when using the slow gears (high cassette rings and smallest crank ring). I can also feel vibrations when the noise is present.

The freehub has been replaced a couple of months ago, in a bike shop.

Any hint or comment about what could be the cause of the problem will be highly appreciated.

Thank you!
Willy

Schweinhund

Andrew R Stewart 

All I hear is the ratchet clicks and some breathing, no undo noise. But I'll bet someone here mentions checking the der hanger alignment (which seems to be a favorite thing to blame for all kinds of stuff Andy

On a second look I think I see some light between the small ring teeth valleys and the chain. If so this might indicate a worn chain. But since I can't touch and feel the bike I can't say anything for sure.

tFUnK

I just hear the ratchet as well. Definitely do not hear air bubbles under water. Maybe I need headphones for this?

maddog34

"air bubbles underwater... " this makes me think you might have bad BEARINGS or a rough Cone or two. Your "new' freehub may not be so nice, internally.... or the installer didn't get things quite right on the Axle bearings setup..
i'd take a close look/feel of that new Freehub.

as to the address... i just copy/pasted this part into youtube... youtu.be/q_5lLROkJdk your 'tube came right up. ;-)

Question: how tight is your Quick Release? they TIGHTEN the axle bearings when snugged , you know.......... Zero play when not QR'd means Too tight when QR'd.... I've had to use a helper pipe on QR's to get them loose before...!

WillyWonkaBike

Thank you all for the replies.

Andrew R Stewart actually the "breathing" noise you hear is indeed the noise I am talking about. I will check the rear derailleur alignment, but I am not sure it will eb the source of the problem as I can shift smoothly thought the cassette rings.
As for the chain and its quick release, this was changed last week, but the problem has been there before. The chain is also shimano 105.

The freehub was exactly the same brand and model as the original one. I bought it myself and was working smoothly. It could be that it was not properly installed...

Just to explain myself, with "air bubbles under water" I meant an intermittent noise going from low to high frequencies. Similar to squeaking brakes. I would say that there is some internal component grinding and/or rubbing, as I can also feel vibrations. What really puzzles me is that the noise is considerably reduced (lower intensity and less frequent) when the chain is in smaller cassette rings and the highest crank ring.

I have uploaded a second video (without breathing). Hopefully you might get a better feeling. Here is the link: https ://youtube.com/shorts/TI2wMGBKWsQ. I would suggest to use headphones, as with normal speakers it is harder to appreciate/distinguish the noise.

In the meantime, I will check the quick release and check whether the noise is still there when loosing it. -> Still there.

Thank you all for your help

FBinNY 

Are you sure it is not the chain rubbing against the front of the railer cage?

rm -rf

Quick release !?
EDIT--sorry, I didn't see maddog34's mention of quick releases. I'll leave this here anyway.

One of the group riders started getting quite annoying noises whenever he pedaled. A pretty continous noise whenever he pedaled, and it was there for a few weeks. I'd call it "crunchy",or "ball bearings clicking together". Your "air bubbles under water" would similar! It sure sounded like his press-fit bottom bracket bearings. He stood up, it was still noisy--so probably not the saddle or seatpost. He checked various bolts on the bike--no change.

I mentioned that a few years ago, I had been annoyed by an intermittent creak when I pushed hard on the pedals. After a lot of troubleshooting to no effect, I was standing next to the bike, and stood on the pedal to flex the frame. Now I thought it was coming from the back of the bike. It was the rear quick release creaking! Wiping it off and adding a thin film of light grease to the plastic cam seat fixed it! And I'm careful to have the correct clamping force now.

So near the end of the ride, he unclamped the quick releases and reclamped them slight tighter. FIXED!! Wow, that noise just didn't sound like anything related to clamping the wheels!! He serviced the quick releases and the noise hasn't come back. (He thought the rear might not have been seated all the way into the dropout, instead of the noise coming from the clamp itself.)

rm -rf

I just viewed your pedaling backward video:
https://www.youtube.com/shorts/TI2wMGBKWsQ#t=1s

My idea of "air bubbles" is different from yours. It's kind of a "whoop" noise? Very odd.

~~~
mavic freehub Death Squeal
Not the same symptoms -- but it is a freehub resonance noise:

Another rider has an older Mavic Kysrium freehub. If not serviced regularly, the plastic bushing inside the freehub will randomly fire off the Death Squeal when he stops pedaling downhill. Wow, it's loud! "What is that! Is it safe to ride??" Getting it greased about once a year keeps it quiet now.

Crankycrank

Are you sure the chain is routed through the rear derailleur pulley cage properly.? Occasionally it will get routed on the outside of one of the "guide tabs" on the cage and can make a noise similar to that.

Andrew R Stewart 

2nd vid is much better at providing the noise. I would want to try a few things to see if I could narrow down the source. Remove the chain from the ring and while keeping the chain from touching rotate the crank in both directions (and not by holding a pedal). Re attach the chain. Lift the rear wheel off the ground and rotate it backwards so the crank also is rotating backwards. Now try pedaling forwards with the rear wheel still off the ground. Remove the chain from the rear cogs and spin the wheel forwards (it's still off the ground) and, by placing your finger on a cog, stop the cassette from rotating but allow the wheel to continue to spin. Try spinning that RH pedal without moving the crank arm.

The noise doesn't sound to me like QR ones, or chain derailment off the pulleys, or pulley knock, or most chain/cage rub I have experienced. It does sound like a bushing or bearing is dry and worn. My next step would be to start taking stuff apart, clean, relube and reassemble. I have felt worn/dry BB bearings before only after I have removed the crank arms (as an example of how discovery can work sometimes). Did the noise start when the freehub body was replaced? Do you know the brand? How much water has this bike seen? How long since the BB was serviced? Is the cassette lock ring tight? Is there a spoke protector behind the cassette?

There are more questions and assessment data points that could come up but these are a good start. Andy (who wasn't serious in mentioning the der hanger alignment)

WillyWonkaBike

I have removed the chain. Then the crank is able to move freely. It does not make any noise at all. Besides, there is no rough friction, it turns smoothly. Therefore, the problem might originate from some component in the rear wheel. I also have removed the wheel quick release. Without the chain, the rear wheel can turn also freely in both directions. When turning in counterclockwise direction (forward pedaling) there is indeed a squeaking noise. This means that the problem might come from the wheel hub and not the freehub.
After some research, I have read that noises can be amplified through the bike frame. That might be reason why I was hearing the noise at the crank and it was like "air bubbles under water". Besides, since the freehub was serviced just a few months ago (in a shop), I though the mechanic would have made sure there was nothing wrong with the wheel hub.

Unfortunately, I do not have the tools neither the knowledge to service the wheel hub just by myself. I will then bring it to the shop.

I would like to thank you all for the assistance and discussion, which eventually helped me to (most probably) find the source of the noise.

maddog34

Remove rear wheel from bike... turn the AXLE with your fingers...does it feel rough or notchy? is there a TINY amount of play in it? if there is a notchy, rough feeling, you have found the noise source... If there is Zero play, You have found your noise source. Typical QR tension is.. set to begin tightening at 1/2 to 1/3 swing remaining when closing QR.... newer Exposed Cam QRs tend towards 1/2 closed... internal Cammed QRs tend towards 1/3 from closed to feel initial contact force. REMEMBER tightening a QR causes the Axle to Compress slightly, and the Bearing will be TOO TIGHT if there is Zero play in the Axle Bearing Adjustment.

Another thing to check(i know, i know!) is the Derailleur Cage alignment.are the cages aligned top-to-bottom? are the rollers in the same plane as the Chain rings? Is the Bottom Idler roller a Concave sided one? the Idler rollers get swapped sometimes...this allows the bottom of the cage to Scrape the roller IF that roller was originally the Top (typically Angular sides) roller........ Rollers have a bit of slop in their bushings by design... NO roller bushing slop means extra chain noise and a much more finicky adjustment...

and ANOTHER thingto check.. is there any excessive drag between the Axle and Freehub? As you were turning the Axle did the freehub remain stationary or did it turn with the axle? a bit of drag is typical... There is typically a SEAL that is pressed into the freehub or onto the Axle bearing Cone... it can, and often Does, get installed too deeply or crooked.... it can rub on the axle bearing balls causing intermittent drag and ODD NOISES......

finding odd bike noises through the internet is like looking for a needle in a haystack from 30 feet away and using an extended pitchfork while wearing Arctic Mittens and welding goggles.

Andrew R Stewart 

Some hubs (usually cup and cone designs) have an external "rubber" seal on the LH side. This seal often has a lip or contoured edge that interfaces with the hub shell. This interface can cause some odd noises, sometimes like a chirp or muffled squeak. A drop of Triflow at the interface cures this.

I really like maddog34's description of doing long distance sleuthing of noises. Andy

oldbobcat

OK, so the spinning crank is smooth and silent. That means the noise is coming from the rear. Let's have a video of that same action but at the rear wheel. I want to see how the chain is passing through the derailleur pulleys onto the cassette cog.

And by the way, the QR skewer tension problem only occurs when the chain is driving the rear wheel, and it's a click or clunk that syncs with the crank. In other words, it isn't a problem when coasting.

Andrew R Stewart 

I will suggest that a QR skewer noise is not as much a crank driving the wheel as is the rider's side to side rock/force on the bike. Andy

oldbobcat

I have embarrassing experience with this. The chain exerts more force on the axle-frame interface than rocking the bike.

maddog34

i recall some problems with using aluminum QR's on Horizontal dropouts proving your point well.....the torque would cause the wheel to mis-align after one somewhat fast start or one steep climb..................

there's a Cannondale F400 in my scrap load right now because of improper QR use... he tightened it like a wingnut instead of using the cam... i bought it anyway, needed the 1 1/4" steering stem.. the xt der.s were a bonus.

Andrew R Stewart 

Perhaps but with most current bikes having vertical drop outs and the drive side QR portion is a simple nut and bolt (compared to the LH side's cam and pivot) I still suggest a rocking force is at play. I will offer front QR skewers making noise on climbs or out of saddle sprints as an example of my experiences, that some QR noises don't involve any chain aspect. Andy

oldbobcat

Well, I imagine they do, but it this case the noise was emanating from a bike leaning against a wall being pedaled backwards excruciatingly slowly. Which is why I requested a video of the rear of the bike before offering any further opinion.

FBinNY 

Rather than argue, we need to think a bit.

For starters consider the QR. It doesn't matter which side is fixed and which has the cam, since they're connected through the axle, and Newton's 3rd Law dictates that they both press equally.

Also, the QR will very rarely be the cause of creaking since sliding loads are on the axle, not the QR which free floats within it.

The QR's job isn't to hold the wheel. It's to compress the frame ends against the axle faces so they can't move. The QR will only slip after the axle has and is now dragging it along by the skewer.

IMO the more likely hub related cause would be within the hub, specifically flex between hub shell and freehub.

OTOH it might be something goofy like a dry RD pulley bushing.