Gears - STX Derailleur adjustment
Mike Apsey
Doug Simon <s32...@student.uq.edu.au> wrote:
>Can anyone please help with some problems I'm having adjusting my gear
>changes?
>I have just put a new Shimano HG50 chain and HG 12/28 cluster onto my
>bike which has an STX derailleur. I am aware of how to do the min/max
>adjustments. I am just wondering why I can get it to run smoothly in the
>smallest rear cog but only by having it not quite right by the time I am
>in the largest rear cog. If I then adjust the derailleur usng the cable
>tensioner screw then the samller cog won't run smoothly again. I suspect
>it has something to do with my Rapid Fire index being not correctly
>adjusted (if that is possible?). Basically, I cannot get each of the
>seven different derailleur positions to align with the seven different
>rear cogs. Can anyone suugest either why this might be happening or refer
>me to a good book that might help. Are there any good overall MTB
>maintenance books all do they each only deal with the specifics of
>different components??
There exists a series of step-by-step adjustments for both front and
rear derailleurs which should be followed to "dial-in" a new or
upgraded system, presuming all the chosen components are compatible
and properly installed.
Each of those steps assures you the latitude to "tweak" any or all of
the adjustment screws/knobs when it's finished. In other words, no
single adjustment is "full-stopped" in either direction. "Hit and
miss" adjustment works, but it is both confusing and slow unless
you're experienced with the logic of the sequence. Tolerances in the
newer "Compact Cassettes" are critical. Meaningful instructions are
(as you suspect) beyond the scope of a brief posted reply.
Suggestions:
Your LBS may have a few extra "Rear Drive System" service instruction
sheets lying around that they will give you. Shimano ships one with
each derailleur and Fisher (for one) includes them in the bag with the
instruction/warranty book. Many LBS's remove them from those packages,
some just don't get them, I guess. #SI-R110B is an STX/Alivio sheet
but the process is the same for all rear deraileurs--so it'd work.
Your LBS may also have a mid to high-end owner's manual which explains
the process. There may also be a sympathetic LBS mechanic willing to
let you watch it happen and learn from him/her. Paying for one dial-in
may cinch that tutoring.
Often, when everything else is working, the pulley will touch the
smallest sprocket causing a chatter on the smallest ring when the
chain is most slack. The "B Tension" adjustment screw is used to pull
the chain from the sprocket and quiet things down.
Lastly, I once accidently placed the wrong length cable housing on the
rear derailleur by mistake, causing a pressure on the derailleur even
the "B-Tensioner" could not satisfactorily overcome. Check that too.
Hope this helps.
--
Mike Apsey
ap...@worldnet.att.net
http://www.geocities.com/Yosemite/2280
Mike Apsey
Almost forgot:
Why the 12-28? Aren't most rear cassette's 11-28 or is this a common
option I'm not aware of? Perhaps that's the problem--smallest gear
one-tooth too big for the STX. Higher end rear ends come in two
lengths for just that reason, I believe. Just a comment--I have no
clue.
Sorry folks, I just saw the cross-post but want these comments kept
together in case of correction. This is really a rec.bicycles.tech
issue that I am answering in rec.bicycles.off-road. <slap>
Doug Simon
Camiel Rouweler
ap...@worldnet.att.net (Mike Apsey) wrote:
>Almost forgot:
>
>Why the 12-28? Aren't most rear cassette's 11-28 or is this a common
>option I'm not aware of? Perhaps that's the problem--smallest gear
>one-tooth too big for the STX. Higher end rear ends come in two
>lengths for just that reason, I believe. Just a comment--I have no
>clue.
FIY:
Most eight-speed cassettes are indeed 11-28, but STX has a seven-
speed cogset. It doesn't have the smallest cog, so it is 12-28.
--
Camiel Rouweler (cami...@surf.phys.tue.nl)
"I don't want to be called 'boy' anymore. I find that term
sexist and demeaning!". "How do you want to be called then?"
"I want to be called 'chromosomally advantaged youth." (Calvin&Hobbes)
Dale
Camiel Rouweler wrote:
> >Why the 12-28? Aren't most rear cassette's 11-28 or is this a common
> >option I'm not aware of? Perhaps that's the problem--smallest gear
> >one-tooth too big for the STX. Higher end rear ends come in two
> >lengths for just that reason, I believe. Just a comment--I have no
> >clue.
>
> speed cogset. It doesn't have the smallest cog, so it is 12-28.
From what I can gather, the standard 7 speed cassette at the STX level
(and others) is an 11-28. It goes 11 13 15 18 21 24 28. 12-28's go
12 14 16 18 21 24 28 and 11-28 8 speeds go 11 12 14 16 18 21 24 28.
Note that a 11-28 7 speed is not available at the old 7 speed XT level
and one has to use a 12-28 or modify an 11-28 from the LX range (it seems
to require a thin spacer before installing the cassette on the freewheel
body).
Dale