rear derailleur adjustment

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


--
flyingdutch

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???

Those screws only set the limits of travel.

If the "L" screw is too tight, the only result will be difficulty
shifting onto the biggest sprocket. If it's too loose, the chain might
overshoot and the derailer go into the spokes.

Difficulty shifting to smaller sprockets is usually caused by cable
friction, or possibly by incorrect indexing adjustment (that's the
adjusting barrel where the cable housing contacts the rear derailer.)

For more detailed instructions, see:

http://sheldonbrown.com/derailer-adjustment

Sheldon "http://sheldonbrown.com/derailer-adjustment" Brown
+-----------------------------------------+
| He not busy being born is busy dying. |
| -Bob Dylan |
+-----------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Sheldon Brown Wrote:

Those screws only set the limits of travel.

If the "L" screw is too tight, the only result will be difficulty
shifting onto the biggest sprocket. If it's too loose, the chain
might
overshoot and the derailer go into the spokes.

suspected as much and from what I had read it did seem that way but
just wanted confirmation. Neveer thought I would get a reply from
someone as noble as yerself tho :-)

Sheldon Brown Wrote:

Difficulty shifting to smaller sprockets is usually caused by cable
friction, or possibly by incorrect indexing adjustment (that's the
adjusting barrel where the cable housing contacts the rear derailer.)

For more detailed instructions, see:

http://sheldonbrown.com/derailer-adjustment

Sheldon "http://sheldonbrown.com/derailer-adjustment" Brown
+-----------------------------------------+
| He not busy being born is busy dying. |
| -Bob Dylan |
+-----------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

cheers for that. Oh well, more shed time for me. not that one needs an
excuse, mind


--
flyingdutch

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

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


--
flyingdutch


There's great articles on adjusting derailleurs and everything else
bike related at Park Tool's website:

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

Just click on the part of the bike you're interested in and it will
take you to the relevant articles.

This site has helped me where other sources of information have failed,
including repair books that I've bought.

Good luck!

-tom