Rear Wheel Resonating Noise

[rob de shan]

Hello All,

I was hoping I could get some advice on a noise issue that developed on recently purchased rear wheel. I've done no more than 120-130 commuting miles. Yesterday, the bike has suddenly started making single 'clunk' sounds as I was approaching a slightly hillier terrain, which got progressively more frequent, now even on small hills or when more pressure is applied to the pedals. Not a chain slipping sound, not a gear slipping sound, just a loud, resonating "clunk".

Having dug through the archive, one person's click is another's clunk and it could be a dozen of different possible things always suggested so I recorded a few clips, narrowing it down in stages to what I think is the faulty part, see the linked video below.

https://www.youtube.com/watch?v=_dwSzaCiu0U

As you can see the resonating sound was clearly coming from the rear wheel. Upon dismounting the wheel and inspecting the cassette I discovered that I could replicate the noise by grabbing individual cassette cog wheels with a chain whip tool by applying force just like a bicycle chain would. The same test was replicated with a single cog to eliminate a possible cassette issue. I should also mention that the cassette had been installed with a supplied 10 speed 1.85mm spacer in place with an additional 1mm spacer on top to that came with the Shimano cassette; it was also originally tightened to the required 40Nm and checked for any play just a few days prior.

I tried to reassemble everything today again, tightening it to slightly under Shimano's max value of 50Nm and it made no difference whatsoever. Grease or no grease on the freehub body. I initially thought that the cassette was jumping up the freehub body's splines as it had already bitten into the freehub body (aluminium) but I no longer think that's the case as you can see the the whole freehub body move in the final part of the video, rather than the cog on its own. Similarly, I thought that spokes might be loose but they sound evenly tightened on the free hub side. I also tried to apply a drop of oil to where they cross - no difference, the sound remains exactly the same.

I inspected the wheel and freehub and see no visible cracks, the spokes seem to be evenly tensioned as well. Like I said the wheel is pretty much brand new. Have I missed anything or is this simply a lemon that needs to go back?

Many thanks!
Pat

[Paulatic]

Sounds like it could be a spoke to me. Do any feel particularly slack?
Are they hand built or factory wheels?

[rob de shan]

Sounds like it could be a spoke to me. Do any feel particularly slack?
Are they hand built or factory wheels?

Thanks for having a look Paulatic.

No slack ones, they all look and sound even: slightly more tension on the freehub side and slightly less on the opposite but also sound appear to be tightened very even - I have no way to measure them, though. I did put thin pieces of cardboard as a test on all spokes crossing points on the non-freehub side to see if it changes anything, the ones on the freehub side are too tight to squeeze anything between them so I was only able to put a drop of oil, but no improvement.

The noise is "spokey" sounding but the freehub body seems to jump under pressure (see the final part of the video with a single cog and chain whip).
edit: hmm, I slowed down the clip to 0.25 speed and might just be the overall vibration. The tooth pattern is very fine on this hub 150 teeth. Difficult to say.

This is the set: https://www.merlincycles.com/pro-build-alex-cx28-chosen-cx-road-wheels-700c-81726.html

From the description: "These wheels are factory built and supplied to us ready to ship."

[Brucey]

from what you say there are two things that spring to mind

1) the freewheel pawls are sticking slightly and/or are not engaging consistently
2) for some reason the sprockets in the cassette are not being gripped correctly.

Maybe you have bottomed this out already, but on the latter point you have the (nominally) correct spacers but tolerances can add up in a bad way. Also there are other possibilities such as the top sprocket being fitted incorrectly; this only goes over ~1mm of spline length and looks like it is running out even when it is fitted correctly. It wouldn't be the first time that someone had not got the splines correctly aligned; if this has happened the larger sprockets may not be held securely; testing with a pair of chain whips (back and forth) shows up if the sprockets are moving too easily or not. That you are getting 'biting' early on suggests that you are getting some movement rather than none. If you have tightened enough of these things you can sometimes tell the difference between clamping a stack of sprockets (slightly squashy) and just the top sprocket (kind of firm) but it isn't guaranteed.

Regarding a) you need to check the pawls are working properly. If you find the pawls sticky but undamaged then some oil + grease mixture (ersatz SFG) ought to provide a good solution. If the pawls are not engaging cleanly (all three at a time) then typically what happens is that any one pawl that is half-engaged tends to pop out under load and this is what makes the noise. When the parts are new the chances of bad pawl engagement are higher; the parts tend to 'run in' over time. If you hold the cranks and turn the wheel forwards very slowly in the frame you may be able to hear if all (three?) pawls click/engage simultaneously or not. If there has been enough noise/slippage then the pawls/seatings can be damaged, and more such slippage/noise events are likely.

hth

cheers

[rob de shan]

(..) top sprocket being fitted incorrectly; this only goes over ~1mm of spline length and looks like it is running out even when it is fitted correctly. It wouldn't be the first time that someone had not got the splines correctly aligned; if this has happened the larger sprockets may not be held securely; testing with a pair of chain whips (back and forth) shows up if the sprockets are moving too easily or not. .

Thanks for the suggestions Brucey. It is a Shimano type cassette so there is only one way to fit it. I made sure that they all go in the exact same positions, facing the right direction, including orientation/position of the plastic spacers. I also made sure that the Shimano-spacer that comes with the cassette and has to be installed is perfectly aligned in a tiny grove against the largest three sprocket set frame.

I also tried both the largest sprockets separately with the chain whip - there are three of them combined - and single ones. I got the same noise regardless. It is a fairly new 12-25 Shimano 5700 model, I had it running on my old wheel for two weeks prior to installing it on the new wheels with no issues.

Regarding a) you need to check the pawls are working properly. If you find the pawls sticky but undamaged then some oil + grease mixture (ersatz SFG) ought to provide a good solution. If the pawls are not engaging cleanly (all three at a time) then typically what happens is that any one pawl that is half-engaged tends to pop out under load and this is what makes the noise. When the parts are new the chances of bad pawl engagement are higher; the parts tend to 'run in' over time. If you hold the cranks and turn the wheel forwards very slowly in the frame you may be able to hear if all (three?) pawls click/engage simultaneously or not. If there has been enough noise/slippage then the pawls/seatings can be damaged, and more such slippage/noise events are likely.

I will try to remove any excess grease and put a drop of precision bearing oil (used for high-end skatebaording bearings) in the pawls to see if it makes any difference. When I looked, neither of them is particularly different or sluggish, they all seem to spring up evenly. Although, the tolerances might be so fine that a naked eye, or untrained person, may not know what to look for. It is a rather 'busy' noise with the 150 teeth so hard to tell.

Thanks again!

[NATURAL ANKLING]

Hi,
Clunking?
Doesn't sound good at all at any time.
Something is loose and first thought as others have said is that the cassette is loose.

When you put the lock ring on in place and don't do it up, Hold it down and turn it backwards till the thread clicks.
Then how many turns till its near tight to spec torque?
Then undo it and remove one cog, replace lock ring turn it backwards whilst holding it down until it clicks again, then count turns till it bottoms out?

If it's a new wheel then who knows what has been assembled and how with what.

[reohn2]

I'd go for one of the freehub pawls not engaging/sticking.
Semi Fluid aerosol grease sprayed into the internals should sort it IMO.

[NUKe]

Think as this new wheel go back to vendor, sounds like a faulty free hub, which also looks tight(might be wrong on that) but it look to have some resistance to going backwards. Either way contact the vendor and get them to sort it out.

[rob de shan]

Thanks everyone for contributing. I can see this is not a straightforward answer.

I would continue to suspect the cassette if I haven't tested it with individual cogs, ruling out any locking ring tension issues, I think.

I have inspected the hub again just to see if anything looks wrong and noticed that one of the pawls is slightly wider / out of spec (?). Again, not sure if it does make any difference in this design but since the other two are completely flush, perhaps that introduces enough misalignment to cause this.

Adding a bit of thinner oil around the pawls and inside the housing has made no difference

I think it is the freehub as the noise always follows any freehub action (backwards or forwards). If I grab a chainwhip tool with the largest cogs installed and push gently to make the noise appear and then hold it in that position, bouncing the wheel a bit to see if any spokes would ring for instance, I am unable to repeat the noise. Whenever I turn and then engage the hub the noise will eventually appear, it is not consistent. You'll get 3 pings in 5 turns. I think this goes in line with the part in the video where you see me riding the bike or standing still. A lot of the crank actions are followed by the noise but if you continue pedalling it stays quiet for a while.

You're probably right Merlin Cycles will need to have a look, I think. Just wanted to make sure I haven't missed anything not be fobbed off with "oh it's the bottom bracket", "you'll be surprised how many noises are caused by a loose seat post" etc.

[NATURAL ANKLING]

Hi,
I've got to admit I never bother looking at the video.
Nice video, got to be a free hub problem hasn't it.Send it back

[pwa]

If it were mine and it were old, so not the responsibility of the shop, I might try removing the sticky-up pawl to see how it behaves with only the two non-suspect pawls. I realise that riding it like that would be asking for trouble, but just as a bench test....

[rob de shan]

Good tips, thanks.

I did go into a bit of trouble with documenting the issue as video footage because if you go by description, this could be interpreted as anything; you really had to dig beyond the usual suspects to get to the bottom of it. Hopefully it will be fairly obvious to the shop.

They haven't commented so far, just asked for a return so they can inspect the items. They will hopefully have a look at the clip when they receive the wheel. I will keep you posted.

Thanks again for the suggestions everyone.

[fausto99]

Well done on producing a video. It demonstrated the problem in the clearest way possible. Much better than long wordy descriptions which could easily be misunderstood.

[rob de shan]

Update

Disappointingly, following a repair from Merlin Cycles (12/06) with this response "I have your wheel back form our workshop, it has be repaired ,tested and is fully functioning." First impression, the wheel looks exactly the same, no parts replaced, no signs of it being ridden/tested, cassettes installed etc. My initial thought was that perhaps it was the spokes all along then if they managed to repair it...

However, I finally installed the wheel tonight and it still has the exact same issue. I did ask for more details on the repair on the 12/06 but my email was completely ignored. My gut feeling is, going by the lack of responses, that they failed to test it properly; possibly tested whether it is true or not, tightened spokes and concluded that it was fine to them... I uploaded another video herehttps://youtu.be/9IAkUt_GJc4 to show that the issue has not been resolved but I am not even sure they bothered looking at the original. A bit disappointed with the whole customer experience from them to be honest.

Also, I've been riding my 10-year old, tired Mavic wheel all month (while waiting for the warranty repair) and have not had a single "ping". It leaves me with no doubts that the wheel in question has a manufacturing defect.

Will need to email them again and ask for a wheel replacement if they failed to rectify the fault. What a waste of a nice evening this was...

[Pebble]

may be its your knee?


seriously though (I did watch the first vid) The noise sounds very similar to when my freehub body needs dismantling, cleaned and put back together. Although when my freehub body makes that noise, it is only once or twice on a ride, and I can never recreate it in the way you can. Can you not try another freehub and then at least you will know 100% that is what it is.

my freehub bodies only has two pawls, (maybe set 120° apart)