Crunchy noise and feel after service

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honesty
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Crunchy noise and feel after service

Post by honesty »

So I had my bike serviced. Replaced chain and cassette, new cables, BB inspection etc. Got it back and I get what can only be described as a crunchy noise (sounds like a train going along as well as you pedal, that sort of rhythmic noise) from the drive train when I pedal. It's worse when putting power down. I also feel it through the pedals. Had a quick discussion with the LBS who did the work and their initial thoughts was trim on the front derailleur, but I have tested that theory (by putting it in a gear where the chain is clear on both sides) and I'm still getting it.

Ideas?
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[XAP]Bob
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Re: Crunchy noise and feel after service

Post by [XAP]Bob »

Does it do it in a workstand?

Is it per pedal rev or per wheel rev or per chain rev?
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pwa
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Re: Crunchy noise and feel after service

Post by pwa »

Narrow it down further by taking the chain off the chain rings and seeing if the BB is running smoothly. If it is, the problem must be in the area of the hub / rear mech. Does the rear wheel spin freely?

Problem with one of the jockey wheels?

Correct chain for your gear system?

Sounds daft, but has the chain been fed correctly around the derailleur? Not rubbing on something there?
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honesty
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Re: Crunchy noise and feel after service

Post by honesty »

It doesnt happen with no load/on the work stand. It doesnt happen in some gears. For example it happens when Im in the middle cog at the front across most of the rear cassette range, but doesnt happen in the small cog at the lowest gears and the high cog in the highest gears (the only times I use the small and large rings!)

Rear wheel rotates smoothly.

Not sure about the chain, the LBS selected it, so I have to accept they've done their job until I can research this!
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honesty
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Re: Crunchy noise and feel after service

Post by honesty »

Also it seems to happen on the down stroke of each crank, so rotation of the chainset rather than wheel.
oldmanonabike
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Re: Crunchy noise and feel after service

Post by oldmanonabike »

Why don't you just take it back to where you got it serviced?
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honesty
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Re: Crunchy noise and feel after service

Post by honesty »

Im going to when I have chance, but in the mean time would like to investigate what could be causing it.
rjb
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Re: Crunchy noise and feel after service

Post by rjb »

I wonder if the shop just replaced the chain and cassette without lubing it! :wink:
It's worth checking they tightened the cassette lock ring next time you have your wheel out.

Bit of detective work required. :wink:
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Re: Crunchy noise and feel after service

Post by MikeF »

pwa wrote:Sounds daft, but has the chain been fed correctly around the derailleur? Not rubbing on something there?
It's not daft. On Shimano derailleurs, at least some, it's possible that the chain has been put on the outside of a guide lug at the back between the two jockey jockey wheels. I've done it myself, :roll: but realised my mistake before riding. The chain needs to be "threaded through" so so it's forward of the guide. Why Shimano need all this when the Suntour ARX just wrapped the chain around the jockey wheels easily without needing to the break the chain, I don't know.
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Vantage
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Re: Crunchy noise and feel after service

Post by Vantage »

My bike did the same when a new cassette and chain were fitted (by me) earlier in the year. Constant horrible grinding feeling, like it had sandpaper on the teeth. No issues on the granny ring or big ring. Just the middle.
I decided the middle ring was knackered as pretty much every mile I do is done in that ring and as I fancied a new chainset anyway, bought one.
Problem gone.
Might be worth a look?
Bill


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Des49
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Re: Crunchy noise and feel after service

Post by Des49 »

As above, I was going to suggest that your chainrings may be a bit worn. The new chain is now running roughly on them, more noticeable on the down stroke as you are applying more pressure then and that will also be the area where the chainring teeth are most worn.

Chainrings can be surprisingly expensive, but at least you will start off with all new transmission. It sounds like you may only need to replace the middle ring anyway.
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honesty
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Re: Crunchy noise and feel after service

Post by honesty »

Makes sense. I do most of my riding in the middle chain ring. It doesnt look too worn, but it could be that a new chain is exacerbating the issue. I'll run in t back to the shop first but if theres nothing else I may bite the bullet and buy a replacement ring.
Des49
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Re: Crunchy noise and feel after service

Post by Des49 »

You can try taking the chainring off and re-mounting it as close to a 90 degree orientation as you can, this will put the most worn teeth away from the area of most pressure and wear. I try and turn chainrings on my fixed and hub gear bikes every so often to even out the wear. It may not be pssible on some chainsets where there are ramps and pins that need to be aligned for shifting.
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Re: Crunchy noise and feel after service

Post by Samuel D »

If it is just roughness arising from using a new chain on a worn chainring, I wouldn’t necessarily replace the chainring. Typically this dies down pretty soon, presumably as the new chain ‘stretches’.

The roughness/vibration of a new chain on a worn cassette or chainring can be astonishingly strong, though, especially when you put the power down. I’ve never fully understood the mechanism.
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