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Discussion Starter · #1 ·
I have changed my chain last week because the "old" one snapped. It had approx. 1200 km and the cassette that I still use (SRAM OG-1070) has the exact same mileage.

Now, when I spin the 11t cog when in the 50t chainring, there's an unpleasing noise. It sounds as if the chain was skipping slightly, although I didn't try to push my hardest to see if (or how bad) it really is skipping - I prefered to just not use that cog. Changing chainring doesn't solve the problem... Besides, the 34x11 combo is useless and causes much chain rub on the outer ring.

Note : all the other cogs are OK.

So far, I've tried adjusting the H-limit screw. Not much to do... The noise and shifting only gets worse if I tune it out of the initial adjustment.
What else can I do?

I just hope that the last cog is not effectively worn out and that I would then need to change the whole cassette... Cassettes have really gone up in price lately. Buying a new one would be a bummer.
 

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That noise is most likely where the gap in the teeth are. The cassette is broken in, but the chain is new. I'd bet it'd go away with time, as the cassette and chain work together.
I have the same cassette, and the sound is still there on several of my smaller cogs after about 600 miles.
 

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Discussion Starter · #3 ·
Peanya said:
That noise is most likely where the gap in the teeth are. The cassette is broken in, but the chain is new. I'd bet it'd go away with time, as the cassette and chain work together.
I have the same cassette, and the sound is still there on several of my smaller cogs after about 600 miles.
So basically, the advice is "ride it 'til the sound goes away"...
I'll try that :)
That solution is much less expensive than a new cassette!
I'll come back in a few hundred miles if it still rattles...
 

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Speed

Svooterz said:
Now, when I spin the 11t cog when in the 50t chainring, there's an unpleasing noise. It sounds as if the chain was skipping slightly, although I didn't try to push my hardest to see if (or how bad) it really is skipping.
100 rpm in a 50/11 is over 35 mph, so that is very impressive. Try "stand up" hard pressure in that gear at a lower speed to see if the chain skips. If it does, then at least that cog needs to be replaced. Can you see the chain trying to shift to the 12t cog, or is the derailleur upper pulley not centered on the 11t cog? When you adjusted the limit screw, are you saying the noise got worse regardless of which way you turned the screw?
 

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Discussion Starter · #5 ·
Kerry Irons said:
100 rpm in a 50/11 is over 35 mph, so that is very impressive. Try "stand up" hard pressure in that gear at a lower speed to see if the chain skips. If it does, then at least that cog needs to be replaced. Can you see the chain trying to shift to the 12t cog, or is the derailleur upper pulley not centered on the 11t cog? When you adjusted the limit screw, are you saying the noise got worse regardless of which way you turned the screw?
The upper pulley is now as close to perfectly centered on the 11t cog as my eyes can tell. The chain doesn't try to shift onto the 12t cog : it seems to bounce a tiny bit vertically, but there's no sidewards movement at all. Besides, when I adjust the limit screw, the noise gets worse regardless of the way which I turn it and I take this as a confirmation that my upper pulley is indeed well centered.

I haven't tried standing up hard on the cog at lower speed... My intuition told me "noisy = avoid" rather than "noisy = test to the edge", but I'll try that next time I go out.

That's the whole extent of the diagnostic... I think the description of the problem is much more complete now that I've answered your questions :)

P.S. You said that if the chain skips when I stand up hard on the 11t cog, that I should replace it. So it IS possible to change a single cog? I figured out it would be quite dumb to change all the cogs when a single one is toast, but I somehow presumed that the component makers would force us into buying a whole cassette when one of its parts starts failing...
 

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"Spinning?"

It may be normal. Large pedal forces at low crank revolutions often set up a chain vibration that could be construed as a "rattle" as said in your second post. But this is very different from the "skipping" you mentioned in your first post. So unless there's some clarification (is it skipping, rattling or both?), that's all I can surmise. :)
 

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How often do you lube your chain? Mine gets noisy after a hundred miles or so after a lube. I think I need a higher viscosity though.
 

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Discussion Starter · #8 ·
wim said:
It may be normal. Large pedal forces at low crank revolutions often set up a chain vibration that could be construed as a "rattle" as said in your second post. But this is very different from the "skipping" you mentioned in your first post. So unless there's some clarification (is it skipping, rattling or both?), that's all I can surmise. :)
Ok I said "if it still rattles" in my second post, but that was just a perhaps careless description of the noise it makes. There is definitly a very slight skipping... as I said to Kerry Irons, the chain bounces a very tiny bit vertically, something I noticed this when spinning the wheel on the repair stand. And yes, I did use the word spinning and I mean it in this case :)

As I said, I have yet to experience high torque, low RPM pedaling onto the cog. I've spun it (at a cadence of 90 to 120 rpm) only for a short time on fast downhills and on the repair stand. As a matter of fact, I first noticed the sound while spinning on a 70 kph (43mph) descent. I don't know yet how that "slight vertical bouncing" will turn out when I push my hardest on the cog.

Oh, and Peanya, I lube my chain approximately at every 150 to 180 kilometers, which is very close to 100 miles. However, it was very freshly lubed when I noticed the noise.
 

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I have found that the B-tension screw adjustment of the rear derailleur will impact the amount of noise coming from the smallest cog.
 

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spinning the the 50/11? - Im guesing downhill slight gradient?
as for breakin a chain - Ive been riding...chains and chains and chains and chains and chains and never broke one - I would love to know how so many people actually break their chains, and 2ndly if they are manly enough to admit that it was a crap installation that caused a weakpoint! :wink5:
 

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Svooterz said:
There is definitly a very slight skipping.
I'll go with Peanya's suggestion then—the cog's slighly worn, the chain is brand new, and all will be right after some miles on the chain.
 

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Chain skipping question

I was reading through the post here and it raised a question in my mind. Are you you more likely to have chain skipping (due to cog wear) in the smaller cogs or the larger cogs? Initially I would have said smaller cogs due to less teeth but with the smaller cogs the chain is more drastically angled over the teeth than with the larger radius cogs and thus may provide more "bite". Thoughts?
 
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