Transmission service problem

"JohnS" <[email protected]> wrote in message "]news:[email hidden]...

Quoted message said:

On a XT 9-sp transmission set-up I've just replaced the chain (following

HG

Quoted message said:

failure) with a PC59 item plus I've renewed the middle front ring. Got the chain length right and
gears shift nicely on the bench. Under load (even fairly light) on the road/trail the chain is
jumping. Not between gears

just

Quoted message said:

within same gear. Can't work out exactly how and where. Jockey wheels are fairly new, cassette
less so but doesn't appear very worn - hard to tell without a fresh one to compare. Wonder if I've
bent the mech at some

point.

Quoted message said:

Cage isn't dead vertical (slightly angled in) when in most gears. Would you expect to replace the
cassette with each chain? John S

Replace the casette and all will be well. I know people who can get away with chainging just the
chain fairly regularly but it has never, ever worked properly for me.

Andy Chequer

On Sun, 23 Mar 2003 13:53:43 +0000, did issue forth:

Quoted message said:

On a XT 9-sp transmission set-up I've just replaced the chain (following HG failure) with a PC59
item plus I've renewed the middle front ring. Got the chain length right and gears shift nicely on
the bench. Under load (even fairly light) on the road/trail the chain is jumping. Not between
gears just within same gear. Can't work out exactly how and where. Jockey wheels are fairly new,
cassette less so but doesn't appear very worn - hard to tell without a fresh one to compare.
Wonder if I've bent the mech at some point. Cage isn't dead vertical (slightly angled in) when in
most gears. Would you expect to replace the cassette with each chain? John S

It's probably the cassette. You'll be very lucky if you manage to get a new chain to work with an
old cassette.

--
Huw Pritchard Replace bounce with huw to reply by mail

JohnS said:

On a XT 9-sp transmission set-up I've just replaced the chain (following HG failure) with a PC59
item plus I've renewed the middle front ring. Got the chain length right and gears shift nicely on
the bench. Under load (even fairly light) on the road/trail the chain is jumping. Not between
gears just within same gear. Can't work out exactly how and where. Jockey wheels are fairly new,
cassette less so but doesn't appear very worn - hard to tell without a fresh one to compare.
Wonder if I've bent the mech at some point. Cage isn't dead vertical (slightly angled in) when in
most gears. Would you expect to replace the cassette with each chain? John S

If it skips no matter which front chainring, then replace the cassette. If it skips only on one
front chainring, start with replacing that chainring (and then probably the cassette 🙂).

The problem is the chain "stretches" (not really... but, wear makes the links further apart). This
wears the gears for a different chain link spacing. When you put the new chain on, each link does
not bear the load because the gear spacing has been worn too far apart. It skips.

I can usually get 3 chains to a cassette, and 3 or 4 to a middle or small chain ring. I replace the
chain when the spacing of 6 links is 6-1/16" (it's supposed to be 6"😉. You can get more life out of
the chain, but not without replacing gears more often. YMMV.

Some people buy 3 chains with quick links (like the PC59) and rotate between them at each cleaning.
This way, all 3 chains and the gears wear about the same.

David

Thanks to all for the swift and considered reponses. Much as I thought. Rotating three chains seems
a sound idea otherwise this sport is going to get even more expensive!

Yours til me tyres wear out John S