flyingdutch wrote:
> OK, Im sure this has been asked (or similar) a zillion times but
> searchig hasnt fixed me up
>
> I hav recently changed cassettes and in the process my indexing at the
> rear has gone awol.
>
> I have set the H+Lscrews as accurately as i can, by my guesstimates
> 
and the shifting is generally 'OK' but on the inner/larger
> cogs its innacurate.
> I can shift up onto the largest one no probs, but going back to the
> smaller ones it seems to need more left-to-right movement of the
> derailleur.
> ie from 26-to-23 its not going far enuff to sit on the 23 cleanly ,etc.
> this applies down to the 21 (or 19. i cant remember accurately...)
> Im wondering if my Lscrew is allowing the inside (ie big cog) too much
> tolerance???
>
> fanx in advance
>
>
It's not yet spring but a good time to review basic gear
adjustments. Take a peek at Sheldon Brown's excellent pages
or any number of other resources.
What you want to do is check the _system_ rather than turn a
screw. That's a major turning point here in the development
of a new mechanic - and we've trained our fair share over
the years. A couple of minutes' observation saves time and
frustration. Don't pick up that screwdriver yet.
Check your chain wear. Is it the chain sticky with crud?
Lubricated? Does the hub bearing have excessive play? Are
the cassette cogs loose on the cassette body?
Undo the cable (Shift rear to low. Stop pedaling. Return
the lever to high. Slip a casing out of its stop). Pedal
and let the changer return to high gear. (unscrew the H
screw if it doesn't go) Get your head behind the changer and
look at the cage. Is it roughly parallel to the chainrings?
Are there cement marks on the outside edges of the changer?
Do the pivot springs both return snappily? Will the body
itself return easily to high gear? Check that by shifting
with your hand.
Place the first two fingers of your left hand behind the
adjuster. Press the right side of the nameplate with your
thumb while pedaling with your right hand. Let go and keep
pedaling. It should return smartly to high gear.
Now do that firmly for low gear. Make sure the changer
doesn't sail off beyond low gear into the spokes.
Slide the casing along the wire. Is is free? Is the end
ferrule kinked? Crud on the BB guide? For integrated
levers, does the wire move easily in the top casing? Pull
the wire with one hand while shifting with the other. For
any casing, pull the wire out, wipe any crud, look for rust
or kinks. Lubricate the wire where it will go in casing.
(We use Rock-N-Roll for nicer modern teflon lined cables,
oil on Huffys).
My point is that the vagaries of actually using your bike
make small degradations that add up. Once in a while you
ought to review the whole system before turning that screw.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
