Chain keeps jumping - can anybody help me?

Your small cog is worn and the chain is not.

The cog gets a hook in each tooth, and when you pedal hard the chain snugs up into the hook. That
leaves not enough room for the oncoming link on the bottom to clear the tip of the next tooth, and
it rests on top. As do all following links until the whole resting chain reaches the top, and that
makes the chain slip until it catches another tooth.

It won't happen unless the chain is snugged up into the tooth, hence it works under no load.

Normally the chain stretches (pivoting points wear) at about the same rate a cog wears, and it all
works out for quite a while, the cog getting more hooked and the chain getting more stretched. A
cheap chain may never skip, by virtue of stretching faster.

If you put on a new chain though, the hook on the favorite cogs causes it to skip under load. A new
cog fixes it, or (easier today) a new freewheel.

Which means of course buying a freewheel removing tool. It never ends.
--
Ron Hardin [email protected]

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

James wrote:

>Hi, I got my old(not used for 7+ years) 18 speed Peugeot Ranger out of the shed the other day and
>surprisingly found it to be all in working condition. I went out for a bit of a ride, but the chain
>broke. So I bought a new one - a Taya
>1/2" x 3/32" x 116 links, bushless width 7.65mm tensile strength over 820kg - which says it's
> compatible with 5,6 & 7 speeds HG/UG, TY15/20/22/30.
>
>BUT now when I try to cycle it, it keeps going out of alignment and jumping on the smallest rear
>cog. It seems ok on the other larger cogs, but not the small one, which is most frustrating. Even
>worse it stays in alignment with no problems if I turn the bike upside down and pedal manually, it
>only goes out when the chain is being pressured/stretched.
>
>Does anybody have any ideas why this is happening or how to fix this?
>
>
>
>
>
There could be many possible reasons behind this. Here are just a few:

Chain is too long, did you remove any links before installing?

The chain is brand new, the rest of your drivetrain componentry is not. The rear cassette and front
rings could be so worn that a new chain will not properly interface with the remains of their pointy
little teeth.

The cables are rusty and fouled, especially inside the housings, preventing smooth travel.

Bent derailleur hanger.

Improperly adjusted limit screws.

Many answers here:

http://www.parktool.com/repair_help/index.shtml

A

>

"James" <[email protected]> wrote in news:[email protected]:
> BUT now when I try to cycle it, it keeps going out of alignment and jumping on the smallest
> rear cog.

Either your chain is not compatible with your freewheel or one of them is worn out.

James at [email protected] wrote on 3/4/03 8:57 AM:

> BUT now when I try to cycle it, it keeps going out of alignment and jumping on the smallest rear
> cog. It seems ok on the other larger cogs, but not the small one, which is most frustrating. Even
> worse it stays in alignment with no problems if I turn the bike upside down and pedal manually, it
> only goes out when the chain is being pressured/stretched.

When you say "out of alignment", do you mean it is not staying on the plane of the smallest cog?

If that is the case, I'd look at the adjustment of the rear derailleur - after 7 years in the shed,
the lube may have hardened, and you might not be getting full swing on the derailleur arm. Same with
the cables - they might have taken a bit of a "set", so when you release pressure with the cable,
they only move about 95% of the way back. Check that the the rear derailleur moves all the way
through its range (remove the back wheel, bike upright, watch that the parrallelogram moves all the
way to the stops).

Or, is it skipping over the cogs when you pedal?

That would put you back to worn cog (which I'd guess is a bit unlikely unless you spent all your
time in the small cog).

Also, look for stiff links in the chain. Bike upright, pedal backwards. The stiff link will hang up
in the derailleur pulleys. Then put your thumbs on the stiff link and work it back and forth
(sideways) to free it.

Hope that helps,

- Jim

On Tue, 04 Mar 2003 16:57:45 +0000, James wrote:

> Hi, I got my old(not used for 7+ years) 18 speed Peugeot Ranger out of the shed the other day and
> surprisingly found it to be all in working condition. I went out for a bit of a ride, but the
> chain broke. So I bought a new one - a Taya 1/2" x 3/32" x 116 links, bushless width 7.65mm
> tensile strength over 820kg - which says it's compatible with 5,6 & 7 speeds HG/UG, TY15/20/22/30.
>
> BUT now when I try to cycle it, it keeps going out of alignment and jumping on the smallest rear
> cog. It seems ok on the other larger cogs, but not the small one, which is most frustrating. Even
> worse it stays in alignment with no problems if I turn the bike upside down and pedal manually, it
> only goes out when the chain is being pressured/stretched.
>
> Does anybody have any ideas why this is happening or how to fix this?

Could be any one of the following: Loose chain, not enough tension. In smaller cogs, there's less
tension. Sticky tensioner. Work cassette, although this usually is in the higher gears too. Shifter
cable tension adjustment.

There's more, but I'd check these 1st.

-Bruce

a recent article in Bicycling addresses this. they also mention checking the frame's alignment
at a shop.

"James" <[email protected]> wrote in message
news:[email protected]...
> Hi, I got my old(not used for 7+ years) 18 speed Peugeot Ranger out of the
shed
> the other day and surprisingly found it to be all in working condition. I
went
> out for a bit of a ride, but the chain broke. So I bought a new one - a
Taya
> 1/2" x 3/32" x 116 links, bushless width 7.65mm tensile strength over
820kg -
> which says it's compatible with 5,6 & 7 speeds HG/UG, TY15/20/22/30.
>
> BUT now when I try to cycle it, it keeps going out of alignment and
jumping on
> the smallest rear cog. It seems ok on the other larger cogs, but not the
small
> one, which is most frustrating. Even worse it stays in alignment with no problems if I turn the
> bike upside down and pedal manually, it only goes
out
> when the chain is being pressured/stretched.
>
> Does anybody have any ideas why this is happening or how to fix this?
>
>

James wrote:

> BUT now when I try to cycle it, it keeps going out of alignment and jumping on the smallest rear
> cog. It seems ok on the other larger cogs, but not the small

What do you mean by "out of alignment". My guess is that the chain is jumping forward, over worn
teeth. That is common with a new chain. Was the small cog used a lot? Can you replace it?

Otherwise, repair the old chain. And eventually, replace both the chain and cluster at the same
time. A 6-speed cluster should be cheap anyway.

"James" <[email protected]> wrote in message
news:[email protected]...
> Hi, I got my old(not used for 7+ years) 18 speed Peugeot Ranger out of the
shed
> the other day and surprisingly found it to be all in working condition. I
went
> out for a bit of a ride, but the chain broke. So I bought a new one - a
Taya
> 1/2" x 3/32" x 116 links, bushless width 7.65mm tensile strength over
820kg -
> which says it's compatible with 5,6 & 7 speeds HG/UG, TY15/20/22/30.
>
> BUT now when I try to cycle it, it keeps going out of alignment and
jumping on
> the smallest rear cog. It seems ok on the other larger cogs, but not the
small
> one, which is most frustrating. Even worse it stays in alignment with no problems if I turn the
> bike upside down and pedal manually, it only goes
out
> when the chain is being pressured/stretched.
>
> Does anybody have any ideas why this is happening or how to fix this?

If you look at the rear cog assembly end-on, you'll notice the teeth of the larger ones are
symmetric, that is, U-shaped. The smallest cog, the one most riders use to exclusion, has worn such
that its teeth are undulate, that is, wave-shaped.

It is worn out.

You'll need to discover whether the rear cog assembly is a cassette or freewheel type and then
replace it.

Our FAQ is very good on this subject.

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

"James" <[email protected]> wrote in message
news:[email protected]...
> BUT now when I try to cycle it, it keeps going out of alignment and
jumping on
> the smallest rear cog. It seems ok on the other larger cogs, >

Not sure if your chain has a removable link, but if it does check that is has been fitted
right way up.

I had exactly the same problem trying to change to the 11 on my campy cassette (relatively new chain
and block - I confess the 11 does not get a lot of use from this little black duck).

I didn't know that some removeable links have to go the right way up (in my case on a Wipperman
chain the link has a gentle curve on one side and a deeper more acute indent on the side which must
be on the outside of the cassette as the chain goes around it - the gentler curved side addresses
the cogs on the block).

Failure to observe this consistently produced the result you describe however much I fiddled with
the rear der cable adjuster and was immediately fixed on putting the link on the right way.

Of course I could have read the instructions that came with the link, but as has been put before
many times, reading instructions need only take place when all else has failed.

Your other posters have more likely causes - its just this is one of the few cycling mechanical
mysteries I have ever managed to solve on my paddy malone.

best, Andrew (remove the .x1 to reply)

"But riding is my special gift, my chiefest, sole delight; Just ask a wild duck can it swim, a
wildcat can it fight... I'll ride this here two-wheeled concern, right straight away, at sight." A B
‘Banjo’ Patterson - "Mulga Bill" 25 July 1896.

> "James" <[email protected]> wrote in message
> news:[email protected]...
> > BUT now when I try to cycle it, it keeps going out of alignment and
> jumping on
> > the smallest rear cog. It seems ok on the other larger cogs, >

"Andrew Price" <[email protected]> wrote in message
news:[email protected]...
> Not sure if your chain has a removable link, but if it does check that is has been fitted
> right way up.
>
> I had exactly the same problem trying to change to the 11 on my campy cassette (relatively new
> chain and block - I confess the 11 does not get a lot of use from this little black duck).
>
> I didn't know that some removeable links have to go the right way up (in
my
> case on a Wipperman chain the link has a gentle curve on one side and a deeper more acute indent
> on the side which must be on the outside of the cassette as the chain goes around it - the gentler
> curved side addresses
the
> cogs on the block).
>
> Failure to observe this consistently produced the result you describe however much I fiddled with
> the rear der cable adjuster and was
immediately
> fixed on putting the link on the right way.
>
> Of course I could have read the instructions that came with the link, but
as
> has been put before many times, reading instructions need only take place when all else
> has failed.
>
> Your other posters have more likely causes - its just this is one of the
few
> cycling mechanical mysteries I have ever managed to solve on my paddy malone.

I was also mistaken about the "asymmetry" of the Wippermann link until a kind r.b.t. reader pointed
out that I was dead wrong. The link may be curved the "wrong way" on the outside but it will
necessarily be the "right way" on the inside. In short this is not the problem. Is your lockring too
big for an 11t??

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

I agree with Ron provided from what I have read thus far. You can verify this by reading John
Forester's book called: Effective Cycling.

It looks like the previous rider spent a lot of time riding in high gear (the smaller gear) in your
cogset. Also the reason you see bad behavior on the smaller gear is because one bad gear as a
percentage of all the gear touching the chain is much greater than one bad tooth in a big 28 tooth
gear. That's why you only get the jumps and skips on your 11, 12, 13 tooth gear.

What to do about it? Of course you can replace the whole cogset, or possibly just the single gear if
you are lucky. I suspect you will not. Here's what you can possibly do.

1. If you were able to remove the single gear, you might be able to flip the gear over and
re-install it and use the other face that is not worn. I know of only one or two models where
this might work.

or

2. Inspect the bad gear and you will see that the at the base of the tooth a groove has been worn
down to create what looks like a hook. You can look on the unworn side of the gear to see what
it should look like. Do you see that?

You can take a small file and re-shape the gear to remove that hook. And you should be able to get
more miles out of it. The good thing is that it's the small gear that does this, and so you have
fewer teeth to work on.

Also, if you screw it up, then you will know you really need to buy a new cogset. I think
harriscyclery.com has the lowest prices on screw on cogsets.

Right Sheldon?

-Wynn

Ron Hardin <[email protected]> wrote in message news:<[email protected]>...
> Your small cog is worn and the chain is not.
>
> The cog gets a hook in each tooth, and when you pedal hard the chain snugs up into the hook. That
> leaves not enough room for the oncoming link on the bottom to clear the tip of the next tooth, and
> it rests on top. As do all following links until the whole resting chain reaches the top, and that
> makes the chain slip until it catches another tooth.
>
> It won't happen unless the chain is snugged up into the tooth, hence it works under no load.
>
> Normally the chain stretches (pivoting points wear) at about the same rate a cog wears, and it all
> works out for quite a while, the cog getting more hooked and the chain getting more stretched. A
> cheap chain may never skip, by virtue of stretching faster.
>
> If you put on a new chain though, the hook on the favorite cogs causes it to skip under load. A
> new cog fixes it, or (easier today) a new freewheel.
>
> Which means of course buying a freewheel removing tool. It never ends.

I had this happen when I swapped cogs from my roadie to Tar Baby, my tourer. Seems like the cog was
warped...don't know how, but looking at it edge-wise, it was warped. Bad/weak cog?

> Hi, I got my old(not used for 7+ years) 18 speed Peugeot Ranger out of the shed the other day and
> surprisingly found it to be all in working condition. I went out for a bit of a ride, but the
> chain broke. So I bought a new one - a Taya 1/2" x 3/32" x 116 links, bushless width 7.65mm
> tensile strength over 820kg - which says it's compatible with 5,6 & 7 speeds HG/UG, TY15/20/22/30.
>
> BUT now when I try to cycle it, it keeps going out of alignment and jumping on the smallest rear
> cog. It seems ok on the other larger cogs, but not the small one, which is most frustrating. Even
> worse it stays in alignment with no problems if I turn the bike upside down and pedal manually, it
> only goes out when the chain is being pressured/stretched.

The chain is under tension when you pedal but it is NOT being stretched.

> Does anybody have any ideas why this is happening or how to fix this?

Three likely reasons.

First, the rear derailleur needs adjustment.

Second, there's a stiff link- backpedalling ought to find it, it'll look like a "V" shape as it
comes out of the derailleur.

Or, third, it's happening because the cogs are worn. In that case, replace the cogs or the freewheel
and all will be well.