Author Topic: Are new chains ever faulty?  (Read 411 times)

Feanor

  • It's mostly downhill from here.
Are new chains ever faulty?
« on: February 11, 2019, 08:44:38 pm »
I've had a bear of a time tonight.

Yesterday, I cleaned my winter commuter bike up.
This involved chain off, cassette off, cranks off, and all put through the cleaner as per normal.
Re-assembly as per normal.

Checked the chain wear with the park tool, and decided it was time for a new chain.
Put new KMC 10-spd chain on.

This morning: un-ridable. Chain skipping under even the most modest loads.
I'm not talking honking on hills; just modest flats.
Hmm, cassette might be a bit old, and skipping on the new chain.
But that's usually only on the most-worn sprockets. Here, it was on *all* sprockets, even the 12 and 25, which see no use!
Swap to a nearly-new cassette off of my disk TT wheel: no better.
Chainwheel?
Same on small, middle, and big.
Swap middle chainring for a spare I found: no better.
Freehub slipping?
Swap rear wheel: no better.

Replace chain with original: all fixed.

Looks like a bad new chain.
Or something else?

bludger

  • Randonneur and bargain hunter
Re: Are new chains ever faulty?
« Reply #1 on: February 11, 2019, 09:02:36 pm »
I've had a bad chain in the sense of a significantly stiff link, which I got swapped under warranty. It was a real nuisance. Appreciate it can be fixed with tools.
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Re: Are new chains ever faulty?
« Reply #2 on: February 11, 2019, 09:03:43 pm »
I had a Taya chain which lasted all of about 50 yards. Threw it away and never bought another.
Rust never sleeps

FifeingEejit

  • Not Small just Far Away at the back
Re: Are new chains ever faulty?
« Reply #3 on: February 11, 2019, 09:06:17 pm »
Can you see where it's skipping when turning by hand?
The 2 most obvious possibilities are stiff links and a quick link that isn't fully engaged.

.

Re: Are new chains ever faulty?
« Reply #4 on: February 11, 2019, 09:38:53 pm »
Quick link would be my first port of call

Feanor

  • It's mostly downhill from here.
Re: Are new chains ever faulty?
« Reply #5 on: February 11, 2019, 09:40:27 pm »
No, it's none of these things.
It skips on each power stroke.

Same new quick link in both scenarios, felt fine by hand. Runs fine on the stand, just not under power. Skipping is not timed to a chain revolution, it's timed to power stroke on the crank.

My current thinking is that I actually have 2 worn cassettes.

The 'nearly new' one I took off my TT wheel was new when I got the Zipp wheel, and has this on it:
-Club evening League: 10 x 10-25 mile TT;
-Open events: 3 x 10m 3 x 25, 1 x 50, 1 x 100, 1 x 24h * (400+);
A modest enough mileage, but:
-done under more power than my normal pootling;
-all done on my Audax bike, who's chain might have seen several thousand k.
I need to check the chain on that bike; I might have killed the cassette.

I'm going to replace the cassette and see what happens.

zigzag

  • unfuckwithable
Re: Are new chains ever faulty?
« Reply #6 on: February 11, 2019, 10:24:14 pm »
i'd measure the chain stretch precisely, with digital calipers, to be certain. then go from there.

stretched chain can damage sprockets/chainrings pretty quickly.

Re: Are new chains ever faulty?
« Reply #7 on: February 11, 2019, 11:13:34 pm »
I'm going to replace the cassette and see what happens.

Same thing happened to me a few months ago with a new chain. 

One new cassette later, and it was fine.

FifeingEejit

  • Not Small just Far Away at the back
Re: Are new chains ever faulty?
« Reply #8 on: February 11, 2019, 11:21:41 pm »
The chain's definitely been shortened enough?
I've had chain slippage from that before...

Re: Are new chains ever faulty?
« Reply #9 on: February 12, 2019, 12:04:13 am »
other folk have measured a lot of  new chains very carefully and they are typically +0% to +0.05% of the nominal 0.5" pitch. However

a) occasionally you will get one that is genuinely  -0.02% or more  under the nominal dimension and
b) until the grease is pushed out of the bushings (*) a chain can behave as if it is ~0.05% shorter than it really is.

(*) and the rollers; note that the roller movement is also restricted in a new chain, and this can interfere with the chain engagement too.

If the chain is either genuinely or temporarily shorter than it should be then it will skip on pretty much any used cassette, even one that would take a new chain quite happily under normal circumstances. In the rarest cases you can get a cassette with one or two sprockets that won't work with a new chain.

It only takes a few microns of metal in the wrong place to cause a chain to skip; the mechanism is that under tension, the chain doesn't feed into the sprocket properly, and one link sits up above the teeth. When this raised link comes near the position where the chain is disengaging from the sprocket, the chain slips forwards about half a link in one go.  You can sometimes wheel the bike forwards whilst bearing down on one pedal, and actually see this happening.

If the chain is not properly tensioned (feeble or sticky rear mech) then this sort of skipping becomes more likely to happen.

 If you fit a new cassette and run it for a hundred miles or so, you may find that you can safely revert back to the present cassette with the same chain.

cheers

Re: Are new chains ever faulty?
« Reply #10 on: February 12, 2019, 06:35:21 am »
I did have a wipperman chain do this on a new cassete after about 200k. Rather inconviently that was 100k into pbp'07. Turned out it was a bad batch. I guess the peining of the pins had been overdone as every link became stiff.

robgul

  • HoECC & Cycle:End-to-End webmaster, S Warwickshire Bike Shop in Wellesbourne
  • . . cyclist, Cytech accredited, manages an LBS
    • Cycle:End-to-End
Re: Are new chains ever faulty?
« Reply #11 on: February 12, 2019, 09:55:38 am »
My money would be on the cassette being the problem with wear  - I fit about 10 chains a week at the shop and have yet to have a dud one (mainly KMC)

Rob