Gears feel rough

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reohn2
Posts: 40711
Joined: 26 Jun 2009, 8:21pm

Re: Gears feel rough

Post by reohn2 »

peetee wrote:Yes, within 200 miles. A journey of a couple of miles on a wet road may spray a chain with a significant amount of road grime. Once you clean it with a clip in chain device the cleaning solution can be washed into the chain gaps and the grit with it. Unless you thoroughly rinse the solution out, and dry it with heat, the cleaning solution clings to the inside of the chain parts, especially between the pins and rollers. Then its free to mingle with the new wet lube and make its job far less effective. The method I use is pretty reliable and I have used it at work for years with no negative comments so far.
I did once forget to rinse and dry (3 jobs on the go at once :oops: ) and the chain wax I applied never set and plastered the rim with yuck when I ran through a gear index check. :oops: :cry:

I've used a clip chain scrubber for donkeys and never had the problems you mention,but I follow a set system which takes no more than a few minutes to complete.
Fill the scrubber with White Spirit,run the chain through it,then repeat,until the WS in the scrubber looks cleanish(I keep any dirty WS in a jam jar where it's let settle and reused,again and again until it's too bad to reuse ie; when I can't see through it after settlement) .
I then run the chain through an old rag to remove any excess WS.
The chain then gets a double dose of aerosol TF2,with any excess wiped off with the old rag.

I remove the chain to clean when the rest of the drivetrain is looking a bit grubby,then I put it in a wide topped plastic bottle and half filled with AS and given a good shake,then repeated until the AS is cleanish,wipe,let dry whilst the rest of the drivetrain is being cleaned then refit,double dose of TF2 wipe off excess and let dry before being ridden.
I never lube my chain before a ride,always after.
I usually get between 4,000,to 4,500 miles out of a Sram 971 chain and three chains before I need a cassette.

EDIT ,I can't say that I've ever noticed much difference between a worn chain and a new one if both are lubed up.However gear changing is a different thing,a worn chain usually has a lot more side slop and as such gearshifting can be "ponderous" at worst and slow at best.
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Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Re: Gears feel rough

Post by Fraz101 »

Here is a short video explaining the issue.

https://youtu.be/AExqWWtkgfY


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Samuel D
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Re: Gears feel rough

Post by Samuel D »

Thanks for the video.

The B-tension isn’t far off although the derailleur cannot follow the shape of the cassette perfectly. However, this should only affect shifting, not roughness in a gear. And shifting isn’t the problem (although you’d get slightly better shifting by tightening the cable a smidgeon with the barrel adjuster on the rear derailleur, just enough to get it to shift down as easily as it shifts up. There’s one down-shift in particular that hesitates in the video).

Chain length looks alright in the video although I can’t see the chainrings.

I now believe you’re noticing a roughness of engagement of the new chain on the partially worn front chainring(s). This is barely audible although it is felt as a vibration on the power stroke while pedalling. It goes away as the chain elongates with wear. You may have already noticed a reduction in this vibration since your first ride with the new chain (albeit offset by your heightened perception because the problem is persisting).

So why would you notice it only in the low gears? Possibly because it is in those gears that you push the pedals hard while climbing hills. In the high gears you’re just cruising along, and possibly at a higher cadence too, which masks the engagement of the chain on each tooth.

Or perhaps you usually use the low gears (big sprockets) with a smaller chainring that happens to be more worn.

If my theory is correct, you will feel the vibration in the smallest sprocket too if you deliberately push the pedals harder than you usually do in that gear. Try this in whatever chainring you usually use with the bigger rear sprockets.

Not much is talked about this effect of a new chain causing vibration with an old chainring, but it exists. You’re a proper pea princess!
Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Gears feel rough

Post by Brucey »

normally a worn chainring would be next on my list but if this were the case then presumably this chain would have run rough from the start and usually would only have become smoother over time.

BTW much of the 'settling' that occurs in use with a new chain and a worn chainring happens because the chainring wears to match the chain. With a new chain I have used chainrings that run as rough as a badger's behind to start with, and after a few hundred miles they are as smooth as silk, even though the chain has not yet worn.

FWIW occasionally I have seen a chain that has not worn badly on the pin bushings but has worn on the rollers. These run rougher than they should.

Certain cleaning regimes (eg that leave solvent on the chain, or a mixture of solvent and oil) promote chain wear, sometimes in the roller, sometimes in the bushings, sometimes in both.


BTW 'premature chain wear' in this context would be an extension of ~1mm in every 12" or so.

FWIW if you have a new chain, you could try fitting that temporarily and seeing if it makes any difference or not.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Re: Gears feel rough

Post by Fraz101 »

Here is a couple of images of my chainrings
ImageImage


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Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Gears feel rough

Post by Brucey »

those chainrings are worn alright; however those photos appear to be next to the crank and that is normally the least worn part of the chainrings. The most worn part of the chainrings, and the part that is relevant to whether the transmission feels rough under load, is the part between the cranks, not the part next to the crank.

If the chainrings are hooked they can run rough with a new chain because the chain doesn't (cannot in fact) engage smoothly under load.

However if this is the problem it is a bit mysterious why you didn't notice it before though.

cheers
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Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Re: Gears feel rough

Post by Fraz101 »

I’m not sure what part of the chain ring you mean?

And for the life of me I cannot remember whether it was like this or not when the chain was initially fitted.

I’m not overly concerned with it. It’s more annoying than anything as I’ve done a quite a bit of work to it recently and would like it running perfectly.

I guess I could always stick the new chain on for a day to see if it rectified the issue.




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Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Gears feel rough

Post by Brucey »

when a crank is horizontal the part of the chainring that is at the top (where the chain is engaging under load) is the part where the tooth wear really matters.

cheers
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NUKe
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Joined: 23 Apr 2007, 11:07pm
Location: Suffolk

Re: Gears feel rough

Post by NUKe »

Are you sure the issue isn't the bottom bracket or the pedals ?
NUKe
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Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Re: Gears feel rough

Post by Fraz101 »

Yes I’m sure. Pedals are free and not rough at all. Been removed cleaned and bearing re greased a month ago.

BB feels fine.




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peetee
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Re: Gears feel rough

Post by peetee »

Hub axle running OK?
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.
Fraz101
Posts: 146
Joined: 15 Feb 2018, 12:47pm

Re: Gears feel rough

Post by Fraz101 »

I fitted new weldtite bearings last weekend.


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reohn2
Posts: 40711
Joined: 26 Jun 2009, 8:21pm

Re: Gears feel rough

Post by reohn2 »

Fraz 101
I agree with SamuelD,I'd give the chain 100 miles to bed into the partly worn cassette.Brucey says the chainrjngs are worn,but I don't think they're are worn unduly,not enough to cause premature wear of the chain IMO.
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Fraz101
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Joined: 15 Feb 2018, 12:47pm

Re: Gears feel rough

Post by Fraz101 »

Thanks for all the replies!
Fraz101
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Joined: 15 Feb 2018, 12:47pm

Re: Gears feel rough

Post by Fraz101 »

Updated video

https://youtu.be/BOKV0WeeGuc

Image


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