Chain 'jumping' at master link



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Alexander Kahn

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I've been using a KMC BMX chain on my single speed since I bought it. I've removed the chain several
times for cleaning using its master link. For the past several months, however, the chain has been
'jumping' and making a loud noise when accelerating rapidly from a low speed when the master link is
on the chainring. If I am out of the saddle when this happens, it can be slighly dangerous. What
does this mean? What caused it? How can I fix it? Will it get worse? Should I buy and learn how to
use a chain tool? Thanks. :D
--
Alexander Kahn
 
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Ron Hardin

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Alexander Kahn wrote:
>
> I've been using a KMC BMX chain on my single speed since I bought it. I've removed the chain
> several times for cleaning using its master link. For the past several months, however, the chain
> has been 'jumping' and making a loud noise when accelerating rapidly from a low speed when the
> master link is on the chainring. If I am out of the saddle when this happens, it can be slighly
> dangerous. What does this mean? What caused it? How can I fix it? Will it get worse? Should I buy
> and learn how to use a chain tool? Thanks. :D
> --
> Alexander Kahn

If it's popping off the chainwheel, it's a worn chainwheel and worn chain combination. Things have
to be pretty worn for this to happen. The links ride out to a radius where there's no more teeth.

If it's skipping on the cogs, it's a worn cog (that has worn faster than the chain - a worn chain
fixes it in fact). The chain snugs up in the hook of a cog tooth and the oncoming link doesn't have
the slack necessary to clear the tip of the oncoming hooked tooth and so rides over it. Hence
skipping under load, to snug the chain into the hook of the worn teeth.
--
Ron Hardin [email protected]

On the internet, nobody knows you're a jerk.
 
A

Alexander Kahn

Guest
Ron Hardin <[email protected]>
> If it's popping off the chainwheel, it's a worn chainwheel and worn chain combination. Things have
> to be pretty worn for this to happen. The links ride out to a radius where there's no more teeth.

> If it's skipping on the cogs, it's a worn cog (that has worn faster than the chain - a worn chain
> fixes it in fact). The chain snugs up in the hook of a cog tooth and the oncoming link doesn't
> have the slack necessary to clear the tip of the oncoming hooked tooth and so rides over it. Hence
> skipping under load, to snug the chain into the hook of the worn teeth.

Thanks, but I don't think that helps.

It seems I have not explained my situation adequately since it is neither of the things you have
described. The chain is not coming off of the chainring. The chain isn't skipping on the cog (only
one). The chain is doing something like skipping, but on the chainring. I push hard, and I am
thrown forward with a loud clicking noise (too loud to describe with the word 'click' but I can't
think of a better one). The chain seems to be skipping and this seems to be happening when the
master link of my chain is on the chainring. I'm fairly sure the master link is related. I hope
that clarifies a bit.

P.S. The chain, freewheel and chainring are all the same age.
--
Alexander Kahn
 
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