New chain skips on _new_ cassette

[Karl Nelson]

I replaced my cassette and chain at the same time. The chain
was an old style with bushings and it skipped on the smaller
sprockets, which I attributed to it being pushed sideways by
the ramps because it was too wide. However, after about
three miles I realized that it was also skipping on the
front chainring, which turned out to be very worn.

Now with new chainrings and a narrower chain ("SRAM-PC58"),
I get skipping on the 13t sprocket. (Both the 15t and 11t
seem OK but I have ridden much yet.) Of the three miles
ridden with the wider chain and worn chainrings, less than
1/2 mile was probably on the 13t sprocket. Most was probably
on the 18t sprocket.

The narrower chain was ridden about 100 feet on the worn
chainrings. I do see wear from this, I think: 24 links
measure about 24 1/32 inches.

I don't have the other chain in front of me to measure it.

Is it possible that the chainrings wore the chain which in
turn wore the cassette sprocket to the point where a new
chain now skips on it, all in 1/2 mile? Any other
explanations? Anything I can do about it?

Also, does my thought for why the chain with bushings was
skipping seem right? It's called a 6/7-speed chain ("KMC-
HP20"), on a 7-speed HG cassette--it seems like it should
have worked.

Thanks, Karl Nelson.

 

[Ron Hardin]

I've had new chains skip on new freewheels (none of this
high tech stuff) and it stopped when the chain wore a
little. That was years ago though.

I'd be surprised if anything skipped on the chainring. The
chain tends to pop off when it skips there. It's winding on
under tension on the chainrings and so doesn't ride up on a
tooth the way it does on a worn cog. So skipping on the
chainring is most likely an optical illusion.

Stiff link is the usual explanation. The stiffness only have
to be stiff against the derailleur tension, not your
pedalling tension.

A skip is caused by a hook in a worn cog, which lets the
chain pull up inside the hook, so the oncoming link doesn't
clear the tip of the next tooth (unless the chain isn't
stretched); the chain then rides on top of the teeth until
the whole army gets to the top of the cog, and then
everything slips until a random link catches a bottom tooth.
A burr on a cog could conceivably cause the same sort of
thing, I guess.
--
Ron Hardin [email protected]

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

 

[Ron Hardin]

Ron Hardin wrote:
> next tooth (unless the chain isn't stretched); the chain
> then rides

unless the chain is stretched

edit error
--
Ron Hardin [email protected]

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

 

[Nomisa]

[email protected] (Karl Nelson) wrote in message news:<[email protected]>...
> I replaced my cassette and chain at the same time. The
> chain was an old style with bushings and it skipped on the
> smaller sprockets, which I attributed to it being pushed
> sideways by the ramps because it was too wide. However,
> after about three miles I realized that it was also
> skipping on the front chainring, which turned out to be
> very worn.
>
> Now with new chainrings and a narrower chain ("SRAM-
> PC58"), I get skipping on the 13t sprocket. (Both the 15t
> and 11t seem OK but I have ridden much yet.) Of the three
> miles ridden with the wider chain and worn chainrings,
> less than 1/2 mile was probably on the 13t sprocket. Most
> was probably on the 18t sprocket.
>
> The narrower chain was ridden about 100 feet on the worn
> chainrings. I do see wear from this, I think: 24 links
> measure about 24 1/32 inches.
>
> I don't have the other chain in front of me to measure it.
>
> Is it possible that the chainrings wore the chain which in
> turn wore the cassette sprocket to the point where a new
> chain now skips on it, all in 1/2 mile? Any other
> explanations? Anything I can do about it?
>
> Also, does my thought for why the chain with bushings was
> skipping seem right? It's called a 6/7-speed chain ("KMC-
> HP20"), on a 7-speed HG cassette--it seems like it should
> have worked.
>
> Thanks, Karl Nelson.

I had same problem with new chain skipping on new cassette.
Stiff link was the culprit.

Backpedal with the bike in a stand and you can often see the
problem link as it comes off the cogs or pulleys. In my
case, it was the one I drove the replacement pin through. I
suspect this is pretty common
- the pin presses the plates together too tightly. Just take
a flat-head screwdriver, stick it btw plates, and gently
flex them so they're looser. I had no problems afterwards.
Hope this works for you.

Nom

 

[Neacalban1]

also, if using a superlink of some sort, they may need
special orientation when installed. I got a connex (I think)
which is asymmetrical, and only goes 1 way. I didnt
understand from the directions initially, and installed it
correctly by accident. the next time I cleaned the chain and
re-installed the link, it began to skip, but only in the
11T. A Park gauge showed less than .25 wear, and I knew the
chain had less than 1000 miles. turned out the link was on
backwards.