Shifting Problem: Skipping Second-To-Largest Cog

[Ride-A-Lot]

(PeteCresswell) wrote:
> SRAM 9.0 with a brand new cog.
>
> Tried moving the chain wrap all the way in each direction w/no luck.
>
> It's shifting perfectly between every cog on all 3 chain wheels except for the
> shift from the third-to-largest to second-to-largest and largest down to
> second-to-largest.
>
> It'll try go engage, but in the end, it either jumps off or just jumps
> back-and-forth between that one and the one it's coming from.
>
> Bad cog?

Check the "B" screw. I had the same problem which was caused by the
derailleur cog to close to the cassette.

--
o-o-o-o Ride-A-Lot o-o-o-o
www.schnauzers.ws

 

[G.T.]

"Ride-A-Lot" <[email protected]> wrote in message
news:[email protected]...
> (PeteCresswell) wrote:
> > SRAM 9.0 with a brand new cog.
> >
> > Tried moving the chain wrap all the way in each direction w/no luck.
> >
> > It's shifting perfectly between every cog on all 3 chain wheels except
for the
> > shift from the third-to-largest to second-to-largest and largest down to
> > second-to-largest.
> >
> > It'll try go engage, but in the end, it either jumps off or just jumps
> > back-and-forth between that one and the one it's coming from.
> >
> > Bad cog?
>
> Check the "B" screw. I had the same problem which was caused by the
> derailleur cog to close to the cassette.
>

I have a feeling that's what he meant by "Tried moving the chain wrap all
the way in each direction."

Greg

 

[(PeteCresswell)]

SRAM 9.0 with a brand new cog.

Tried moving the chain wrap all the way in each direction w/no luck.

It's shifting perfectly between every cog on all 3 chain wheels except for the
shift from the third-to-largest to second-to-largest and largest down to
second-to-largest.

It'll try go engage, but in the end, it either jumps off or just jumps
back-and-forth between that one and the one it's coming from.

Bad cog?
--
PeteCresswell

 

[(PeteCresswell)]

Per Ride-A-Lot:
>Check the "B" screw. I had the same problem which was caused by the
>derailleur cog to close to the cassette.

Bingo.

That plus cable stretch.

I think I had everything almost right when I put everything together the nite
before - but the "B" adjust was a little more than the .25" specified in the
instructions. It worked well enough then, but the cable stretched beyond it's
adjustment range during the day.

I think the root problem was that, when I put it all together, I tried to get it
about right with the barrel adjuster in the middle of it's range - figuring that
would give me the most latitude when things settled down in use.

Wrong, I think: too much initial stretch.

This time, rolled the barrel adjuster back to zero, assembled the der with the
cable about tight - a little too tight, even. Then I shifted the der to mid
cog and pushed on it with my hand - stretching the cable a little.

Then I shifted the der back to the smallest cog and had to tighten up a little
on the barrel adjuster.

Seems tb working ok now. Gotta get somebody to ride it to be sure. (this is my
loaner bike...)
--
PeteCresswell