REAR MECH ALINEMENT PROBS

[Ade]

im current having problems alining a 8 speed "shimano" rear mech.

the problem is if i aline the system with the low gear i.e. gear 8 the chain wont reach gear 1. (and
visa versa) .

so i think the problem is the range to the system is not enough how do i alter this?

[Mseries]

ADE wrote:
> im current having problems alining a 8 speed "shimano" rear mech.
>
> the problem is if i aline the system with the low gear i.e. gear 8 the chain wont reach gear 1.
> (and visa versa) .
>
> so i think the problem is the range to the system is not enough how do i alter this?

You mean the rear mech will not move far enough to make the jockey wheel align below the sprocket on
the other end ? Without a chain does it look OK ? Have you tinkered with the two stops on the mech.
These are two small screws usually on the back of the mech. One stops the mech going too close to
the wheel, the other too far away from the wheel. Fiddle with them to learn how they work.

I presume you have eight speed levers and cassette and your mech is 8 speed compatible and not an
old six or seven. The mech doesn't really have any speeds just a distance over which it will travel.
Ones designed for six may not move far enough to cover eight sprockets.

I think your problem will be the stop adjusters on the mech. See if Sheldon Brown has any info, I am
sure he will. Shimano do on their site. It'll be all pretty generic so don't worry if you do not see
you particular model of mech.

--
The Reply & From email addresses are checked rarely.

[Simon Brooke]

"ADE" <BARRY@AOL.COM> writes:

> im current having problems alining a 8 speed "shimano" rear mech.
>
> the problem is if i aline the system with the low gear i.e. gear 8 the chain wont reach gear 1.
> (and visa versa) .
>
> so i think the problem is the range to the system is not enough how do i alter this?

You want to start with the chain on the middle ring by aligning the chain when it is on the
middle cog at the back. Then change up to smallest rear cog (highest gear). If it won't reach,
slightly loosen the high end stop screw - it will have a little 'H' beside it. If it overshifts
beyond the highest gear you want to slightly tighten the high end stop screw. Now change down to
the largest cog on the back (lowest gear). If it won't reach slightly loosen the low end stop
screw - with a little 'L' beside it. If it overshifts beyond the largest cog slightly tighten the
low end stop screw.

If you only have two chain rings use the larger chain ring while setting the high end stop screw and
the smaller when setting the low end.

Here endeth the lesson.

--
simon@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/ Windows 95: You, you, you! You
make a grown man cry...
M. Jagger/K. Richards

[Ade]

> You mean the rear mech will not move far enough to make the jockey wheel align below the sprocket
> on the other end ? Without a chain does it look
OK
> ? Have you tinkered with the two stops on the mech. These are two small screws usually on the back
> of the mech. One stops the mech going too close to the wheel, the other too far away from the
> wheel. Fiddle with them to learn how they work.

- these two stops are not being used (total lose) as i said of the befour i can only get the chain
to use 7 of the eight gears (ie 1 - 7 if set on the lower gear or 2-8 if set on the higher gear)

> I presume you have eight speed levers and cassette and your mech is 8
speed
> compatible and not an old six or seven. The mech doesn't really have any speeds just a distance
> over which it will travel. Ones designed for six
may
> not move far enough to cover eight sprockets.
>
the bike is a gt aggressor - brought from halford about april time, the gear wernt set correctly
when brought (p.s. it not my bike, but a freinds)

[Mseries]

ADE wrote:
>> You mean the rear mech will not move far enough to make the jockey wheel align below the
>> sprocket on the other end ? Without a chain does it look OK ? Have you tinkered with the two
>> stops on the mech. These are two small screws usually on the back of the mech. One stops the
>> mech going too close to the wheel, the other too far away from the wheel. Fiddle with them to
>> learn how they work.
>
> - these two stops are not being used (total lose) as i said of the befour i can only get the chain
> to use 7 of the eight gears (ie 1 - 7 if set on the lower gear or 2-8 if set on the higher gear)

Does the mech move far enough without the chain ? You need to see if the chain is the problem or the
mech. Has the lever got seven clicks or six ? The clicks refer to the spaces between the gears. What
I am getting at is this. Does the lever allow the mech to move far enough ? If it all looks OK it is
probably due to mal-adjustment. You have the two screws I mentioned before and a cable adjuster to
play with.

Remember also that is it not recommended that you use the small front chainring with the
smallest rear sprocket and largest front with largest rear. Chains tend not to like flexing too
much sideways. Can you actually use large(front)-small(rear) AND small(front)-large(rear) ? If
so I wouldn't worry about it, you (err your friend) will have a very similar gear elsewhere in
the cassette.

--
The Reply & From email addresses are checked rarely.

[Pete Biggs]

ADE wrote:
> - these two stops are not being used (total lose) as i said of the befour i can only get the chain
> to use 7 of the eight gears (ie 1 - 7 if set on the lower gear or 2-8 if set on the higher gear)

Put the bike in top gear (largest front chainring + smallest rear cog) and make sure the rear gear
cable is taut and is not badly frayed where it is clamped to the derailleur. Re-attach or replace it
if necessary and adjust cable.

Have a go with these instructions: http://sheldonbrown.com/derailer-adjustment.html

~PB

[Simon Brooke]

"ADE" <BARRY@AOL.COM> writes:

> > You mean the rear mech will not move far enough to make the jockey wheel align below the
> > sprocket on the other end ? Without a chain does it look
> OK
> > ? Have you tinkered with the two stops on the mech. These are two small screws usually on the
> > back of the mech. One stops the mech going too close to the wheel, the other too far away from
> > the wheel. Fiddle with them to learn how they work.
>
> - these two stops are not being used (total lose) as i said of the befour i can only get the chain
> to use 7 of the eight gears (ie 1 - 7 if set on the lower gear or 2-8 if set on the higher gear)

If both stop screws are loose you're stuffed: it isn't going to work. You need a new rear mech.

--
simon@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/ Windows 95: You, you, you! You
make a grown man cry...
M. Jagger/K. Richards

[Pete Biggs]

ADE wrote:
> - these two stops are not being used (total lose) as i said of the befour i can only get the chain
> to use 7 of the eight gears (ie 1 - 7 if set on the lower gear or 2-8 if set on the higher gear)

I'm not sure what you mean. Trouble is some people say "number one" to mean the largest, some the
smallest, and some people get high and low gears all mixed up. Let's stick to "smallest" and
"largest" (or "inner" and "outer" for the chainrings).

MSeries makes a good point about cross-over gears. Don't use those bad gears. That applies to all
derailleur systems on all normal bikes so you're not loosing anything.

~PB

[Pete Biggs]

Simon Brooke wrote:

> If both stop screws are loose you're stuffed: it isn't going to work. You need a new rear mech.

Not necessarily. All kind of weird things can happen if the cable is way out of adjustment or
something is bent/broken or missing, etc. I reckon it's worth trying to readjust it first. Might
just be the cross-over gears that are not working anyway.

~PB