Chain won't stay on largest cog

I have a rear derailleur adjustment question. It is Shimano RSX, 7 speed.
I cannot keep the chain stay at the largest cog. It falls back to the 2nd
from largest unless I keep pressing the shifter. L limit screw setting
seems to be correct, because if I turn it 1/4 turn more, then the chain
jumps over the largest cog.. If I make the cable tighter by turning an
adjustment barrel, the chain won't shift down to the smallest cog. Is
there anything else I can try ? Could this be caused by a worn chain or a
gear ? TIA.

yk wrote:
I have a rear derailleur adjustment question. It is Shimano RSX, 7 speed.
I cannot keep the chain stay at the largest cog. It falls back to the 2nd
from largest unless I keep pressing the shifter. L limit screw setting
seems to be correct, because if I turn it 1/4 turn more, then the chain
jumps over the largest cog.. If I make the cable tighter by turning an
adjustment barrel, the chain won't shift down to the smallest cog. Is
there anything else I can try ? Could this be caused by a worn chain or a
gear ?

See if your changer is aligned in the vertical before you
have a long sad story like our 'changer in spokes'
concurrent thread poster.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Has it ever worked? Is the derailleur designed for the size of the largest
cog; is it an MTB cassette (28+ teeth) on a road derailleur (designed for
27 teeth)?

Justin Vincent

--

"yk" wrote in message
...
I have a rear derailleur adjustment question. It is Shimano RSX, 7 speed.
I cannot keep the chain stay at the largest cog. It falls back to the 2nd
from largest unless I keep pressing the shifter. L limit screw setting
seems to be correct, because if I turn it 1/4 turn more, then the chain
jumps over the largest cog.. If I make the cable tighter by turning an
adjustment barrel, the chain won't shift down to the smallest cog. Is
there anything else I can try ? Could this be caused by a worn chain or
a
gear ? TIA.

yk wrote:
I have a rear derailleur adjustment question. It is Shimano RSX, 7 speed.
I cannot keep the chain stay at the largest cog. It falls back to the 2nd
from largest unless I keep pressing the shifter. L limit screw setting
seems to be correct, because if I turn it 1/4 turn more, then the chain
jumps over the largest cog.. If I make the cable tighter by turning an
adjustment barrel, the chain won't shift down to the smallest cog. Is
there anything else I can try ? Could this be caused by a worn chain or a
gear ? TIA.



May be that you rear der is so 'over adjusted' that the first 'click' of
the lever, doesn't move the rear der to the next cog. Shift all the way
down, loosen the inner wire, screw the barrel adjuster almost all the
way down, pull the inner wire tight and reconnect. Then shift once, see
if the chain moves to the next cog, fine adjust, then shift up the cogset.

The Park Tool website (http://www.parktool.com/) has excellent,
step-by-step instructions for adjusting index-shift systems.

"Justin Vincent" wrote in message
. ..
Has it ever worked? Is the derailleur designed for the size of the largest
cog; is it an MTB cassette (28+ teeth) on a road derailleur (designed for
27 teeth)?

Justin Vincent

You may be right ! It is a road bike with 26inch wheels. It is REI's
Novara Radonee. I don't know history of bike. I got it used. It has
Shimano RSX STI shifter. and both rear derailluer and rear wheel hub have
RSX mark. They are probably original. As you guessed, the largest cog has
28 teeth. Does it mean MTB cassette and not compatible with the derailluer
?
Thanks.

"Qui si parla Campagnolo" wrote in message
news:1112019254.ede2092292056fbccaf725dd7832596a@t eranews...

May be that you rear der is so 'over adjusted' that the first 'click' of
the lever, doesn't move the rear der to the next cog. Shift all the way
down, loosen the inner wire, screw the barrel adjuster almost all the
way down, pull the inner wire tight and reconnect. Then shift once, see
if the chain moves to the next cog, fine adjust, then shift up the cogset.

I replaced the shift cable and follow the derailleur adjustment procedure
from scratch.
The problem is that the rear pulley does not line up with the largest cog
unless I keep holding the shifter.
There is a small offset that causes the chain to fall to the next cog.

On Mon, 28 Mar 2005 19:34:03 -0800, yk wrote:


"Qui si parla Campagnolo" wrote in message
news:1112019254.ede2092292056fbccaf725dd7832596a@t eranews...

May be that you rear der is so 'over adjusted' that the first 'click' of
the lever, doesn't move the rear der to the next cog. Shift all the way
down, loosen the inner wire, screw the barrel adjuster almost all the
way down, pull the inner wire tight and reconnect. Then shift once, see
if the chain moves to the next cog, fine adjust, then shift up the cogset.

I replaced the shift cable and follow the derailleur adjustment procedure
from scratch.
The problem is that the rear pulley does not line up with the largest cog
unless I keep holding the shifter.
There is a small offset that causes the chain to fall to the next cog.

There is a reasonable probability that your derailleur bracket is bent.
This will cause the problem you are having. There are tools to straighted
bent brackets. Check with a good local bike store.

"A Muzi" wrote in message
...

See if your changer is aligned in the vertical before you
have a long sad story like our 'changer in spokes'
concurrent thread poster.


No matter what I do, a rear pulley won't lineup to the largest cog once I
release the shift lever.

wrote in message
ups.com...
The Park Tool website (http://www.parktool.com/) has excellent,
step-by-step instructions for adjusting index-shift systems.

Actually I follow this instruction step by step, but cannot make the pulley
line up to the largest cog.
The problem may be an incompatible cassette or damaged derailleur ?