Thumb shifter not catching



I just dug my 1996 Mongoose Alta out of the storage closet after a year
hiatus. Upon test-riding last night, I found that the thumb 1-7
shifter on the right would not shift to a lower gear. (The left
shifter 1-3 worked fine.) On occasion I could shift from 7 to 6, but
no lower. I adjusted the rear derailer a half dozen times, but still
no luck. The gears in the shifter wouldn't catch. I took apart the
gear shift to find if any teeth brok apart, but they hadn't. Though I
wasn't quite sure that the thumb shifter tooth was correctly positioned
in the shifter teeth. Need help!
 
B

Brian Huntley

Guest
[email protected] wrote:
> I just dug my 1996 Mongoose Alta out of the storage closet after a year
> hiatus. Upon test-riding last night, I found that the thumb 1-7
> shifter on the right would not shift to a lower gear. (The left
> shifter 1-3 worked fine.) On occasion I could shift from 7 to 6, but
> no lower. I adjusted the rear derailer a half dozen times, but still
> no luck. The gears in the shifter wouldn't catch. I took apart the
> gear shift to find if any teeth brok apart, but they hadn't. Though I
> wasn't quite sure that the thumb shifter tooth was correctly positioned
> in the shifter teeth. Need help!


It's entirely possible the cable is the problem - they often sieze on
unused bikes.

If you're not in a position to replace it right away, try undoing it
from the derailer to get some slack, then work it back and forth a bit.
Once you can get it moving, try to get some light oil to drip down it
into the housing. If it's frayed on the end, be careful not to pull it
so far it that the end goes up inside the outer cable, or you might
have bigger problems. Note that modern cables actually work better
without lubrication (they have teflon-like linings) so this is really a
"quick fix" and not permenant.

A full set of shifter cables, including housings, should cost under $20
or so at your LBS, installation not included.
 
V

Vee

Guest
Brian Huntley wrote:
> [email protected] wrote:
> > I just dug my 1996 Mongoose Alta out of the storage closet after a year
> > hiatus. Upon test-riding last night, I found that the thumb 1-7
> > shifter on the right would not shift to a lower gear. (The left
> > shifter 1-3 worked fine.) On occasion I could shift from 7 to 6, but
> > no lower. I adjusted the rear derailer a half dozen times, but still
> > no luck. The gears in the shifter wouldn't catch. I took apart the
> > gear shift to find if any teeth brok apart, but they hadn't. Though I
> > wasn't quite sure that the thumb shifter tooth was correctly positioned
> > in the shifter teeth. Need help!

>
> It's entirely possible the cable is the problem - they often sieze on
> unused bikes.
>
> If you're not in a position to replace it right away, try undoing it
> from the derailer to get some slack, then work it back and forth a bit.
> Once you can get it moving, try to get some light oil to drip down it
> into the housing. If it's frayed on the end, be careful not to pull it
> so far it that the end goes up inside the outer cable, or you might
> have bigger problems. Note that modern cables actually work better
> without lubrication (they have teflon-like linings) so this is really a
> "quick fix" and not permenant.
>
> A full set of shifter cables, including housings, should cost under $20
> or so at your LBS, installation not included.


It's not the cable, it's the shifter. Spray it out with WD-40 or
another light lube or solvent. The lube in them gets sticky over time
and the pawls won't engage as you describe.

-Vee
 
M

Michael Press

Guest
In article
<[email protected]>
,
"Vee" <[email protected]> wrote:

> Brian Huntley wrote:
> > [email protected] wrote:
> > > I just dug my 1996 Mongoose Alta out of the storage closet after a year
> > > hiatus. Upon test-riding last night, I found that the thumb 1-7
> > > shifter on the right would not shift to a lower gear. (The left
> > > shifter 1-3 worked fine.) On occasion I could shift from 7 to 6, but
> > > no lower. I adjusted the rear derailer a half dozen times, but still
> > > no luck. The gears in the shifter wouldn't catch. I took apart the
> > > gear shift to find if any teeth brok apart, but they hadn't. Though I
> > > wasn't quite sure that the thumb shifter tooth was correctly positioned
> > > in the shifter teeth. Need help!

> >
> > It's entirely possible the cable is the problem - they often sieze on
> > unused bikes.
> >
> > If you're not in a position to replace it right away, try undoing it
> > from the derailer to get some slack, then work it back and forth a bit.
> > Once you can get it moving, try to get some light oil to drip down it
> > into the housing. If it's frayed on the end, be careful not to pull it
> > so far it that the end goes up inside the outer cable, or you might
> > have bigger problems. Note that modern cables actually work better
> > without lubrication (they have teflon-like linings) so this is really a
> > "quick fix" and not permenant.
> >
> > A full set of shifter cables, including housings, should cost under $20
> > or so at your LBS, installation not included.

>
> It's not the cable, it's the shifter. Spray it out with WD-40 or
> another light lube or solvent. The lube in them gets sticky over time
> and the pawls won't engage as you describe.


Time for my semi-annual WD-40 rant. The stuff is a
penetrating lubricant, yes, but the residue becomes a
tar-like substance. Thus the cycle of another
application regenerates. Better to flush out the WD-40
after it does its job and apply a lubricant that
remains a lubricant. Best to use a penetrating
lubricant that does not transmogrify into gum.

Why do you think so much WD-40 is sold?
 
C

catzz66

Guest
Michael Press wrote:
>
>
> Time for my semi-annual WD-40 rant. The stuff is a
> penetrating lubricant, yes, but the residue becomes a
> tar-like substance. Thus the cycle of another
> application regenerates. Better to flush out the WD-40
> after it does its job and apply a lubricant that
> remains a lubricant. Best to use a penetrating
> lubricant that does not transmogrify into gum.
>
> Why do you think so much WD-40 is sold?


What would you suggest as a replacement for WD-40 that would allow me to
target the moving parts inside my brifters? I have to keep my bike
indoors and they get dodgy in the wintertime. I guess the warm dry air
dries them out. I usually have to lube them at least once each winter.
 
J

JeffWills

Guest
catzz66 wrote:
>
> What would you suggest as a replacement for WD-40 that would allow me to
> target the moving parts inside my brifters? I have to keep my bike
> indoors and they get dodgy in the wintertime. I guess the warm dry air
> dries them out. I usually have to lube them at least once each winter.


You're having problems because WD-40 isn't a lube. Once it dries out,
it gums up the works. Try using a spray lubricant instead- I've used
LPD-9 since it was a Schwinn product. It's available from Giant dealers
nowadays:
http://www.giant-bicycle.com/us/035.000.000/035.000.000.asp?model=10919

Jeff
 
Vee wrote:
> Brian Huntley wrote:
> > [email protected] wrote:
> > > I just dug my 1996 Mongoose Alta out of the storage closet after a year
> > > hiatus. Upon test-riding last night, I found that the thumb 1-7
> > > shifter on the right would not shift to a lower gear. (The left
> > > shifter 1-3 worked fine.) On occasion I could shift from 7 to 6, but
> > > no lower. I adjusted the rear derailer a half dozen times, but still
> > > no luck. The gears in the shifter wouldn't catch. I took apart the
> > > gear shift to find if any teeth brok apart, but they hadn't. Though I
> > > wasn't quite sure that the thumb shifter tooth was correctly positioned
> > > in the shifter teeth. Need help!

> >
> > It's entirely possible the cable is the problem - they often sieze on
> > unused bikes.
> >
> > If you're not in a position to replace it right away, try undoing it
> > from the derailer to get some slack, then work it back and forth a bit.
> > Once you can get it moving, try to get some light oil to drip down it
> > into the housing. If it's frayed on the end, be careful not to pull it
> > so far it that the end goes up inside the outer cable, or you might
> > have bigger problems. Note that modern cables actually work better
> > without lubrication (they have teflon-like linings) so this is really a
> > "quick fix" and not permenant.
> >
> > A full set of shifter cables, including housings, should cost under $20
> > or so at your LBS, installation not included.

>
> It's not the cable, it's the shifter. Spray it out with WD-40 or
> another light lube or solvent. The lube in them gets sticky over time
> and the pawls won't engage as you describe.


It's a thumb shifter, not an STI shifter. It may not even have
any pawls, just a set of detents. Thumbies are fairly simple.
It's not clear from the OP whether the thumbie is shifting down
but not settling into position, or whether it is resisting being
pushed down at all. If the latter, the cause is usually sticky cables
(or sometimes a sticky derailleur parallelogram), not the shifter.

Things to check include where the cables enter the housings and
any place the cables are routed through a fitting in the frame
(such as an under-the-BB cable guide).

Ben
 
C

catzz66

Guest
JeffWills wrote:
> catzz66 wrote:
>
>>What would you suggest as a replacement for WD-40 that would allow me to
>>target the moving parts inside my brifters? I have to keep my bike
>>indoors and they get dodgy in the wintertime. I guess the warm dry air
>>dries them out. I usually have to lube them at least once each winter.

>
>
> You're having problems because WD-40 isn't a lube. Once it dries out,
> it gums up the works. Try using a spray lubricant instead- I've used
> LPD-9 since it was a Schwinn product. It's available from Giant dealers
> nowadays:
> http://www.giant-bicycle.com/us/035.000.000/035.000.000.asp?model=10919
>
> Jeff
>


Thanks. I'll see if I can track it down this weekend.
 
M

MattyMattyChooChoo

Guest
> It's a thumb shifter, not an STI shifter. It may not even have
> any pawls, just a set of detents. Thumbies are fairly simple.
> It's not clear from the OP whether the thumbie is shifting down
> but not settling into position, or whether it is resisting being
> pushed down at all. If the latter, the cause is usually sticky cables
> (or sometimes a sticky derailleur parallelogram), not the shifter.
>
> Things to check include where the cables enter the housings and
> any place the cables are routed through a fitting in the frame
> (such as an under-the-BB cable guide).


The index finger portion of the gear shifter works fine when I reach
down ot the read deraileur and start in a lower gear. I took the cover
from the bottom of the gear-shift and noticed that the tooth attached
to the thumb lever would not catch the teeth on the wheels intended to
shift the gears.

I would guess (and it may be a poor guess) that if the index finger
trigger catches, then the cable should be okay.

I did not disassemble the gear-shift any more than removing the plastic
cover, but I could not seem to manipulate the thumb lever in any way to
make the lever catch the tooth on the wheel. Is there something that i
need to tighten, hit with a hammer, or jam with a screwdriver?
 
J

JeffWills

Guest
MattyMattyChooChoo wrote:
>
> I did not disassemble the gear-shift any more than removing the plastic
> cover, but I could not seem to manipulate the thumb lever in any way to
> make the lever catch the tooth on the wheel. Is there something that i
> need to tighten, hit with a hammer, or jam with a screwdriver?


In general, you can't disassemble your Rapidfire shifter (that's
Shimano's name for what you're describing) any more than you have.
There's a variety of small pawls and springs in there that were never
available as spare parts.

Spray it down with lube. It sounds like the downshift pawl is stuck and
not catching. Clean it off, put the cover back on, put in a new cable,
and ride the bike. If the shifter still doesn't work, you'll have to
find a replacement shifter.

Jeff
 
J

Johnny Sunset aka Tom Sherman

Guest
Jeff Wills wrote:
>
> In general, you can't disassemble your Rapidfire shifter (that's
> Shimano's name for what you're describing)...


I thought it was "Rabidfire". ;)

What we need are 7, 8 and 9-speed XT quality level indexed thumb
shifters with optional friction mode.

--
Tom Sherman - Here, not there.
 
J

JeffWills

Guest
Johnny Sunset aka Tom Sherman wrote:
> Jeff Wills wrote:
> >
> > In general, you can't disassemble your Rapidfire shifter (that's
> > Shimano's name for what you're describing)...

>
> I thought it was "Rabidfire". ;)
>


Back in the day, it was "RapidFailure".

> What we need are 7, 8 and 9-speed XT quality level indexed thumb
> shifters with optional friction mode.
>


Easy enough, with Pauls "Thumbies" mounts:
http://www.paulcomp.com/frmthumb.html . You can even do 10-speed if you
combine them with the latest shifters:
http://cycle.shimano-eu.com/catalog/cycle/products/component.jsp?PRODUCT<>prd_id=845524441763091
(shrunken URL: http://tinyurl.com/ylk93a)

Jeff
 
M

Michael Press

Guest
In article <[email protected]>,
catzz66 <[email protected]> wrote:

> Michael Press wrote:
> >
> >
> > Time for my semi-annual WD-40 rant. The stuff is a
> > penetrating lubricant, yes, but the residue becomes a
> > tar-like substance. Thus the cycle of another
> > application regenerates. Better to flush out the WD-40
> > after it does its job and apply a lubricant that
> > remains a lubricant. Best to use a penetrating
> > lubricant that does not transmogrify into gum.
> >
> > Why do you think so much WD-40 is sold?

>
> What would you suggest as a replacement for WD-40 that would allow me to
> target the moving parts inside my brifters? I have to keep my bike
> indoors and they get dodgy in the wintertime. I guess the warm dry air
> dries them out. I usually have to lube them at least once each winter.


LPS-1 and LPS-2. Both are a penetrating lubricant and
given 24-48 hours will loosen some very stubborn locked
up moving parts. LPS-1 is a dry lubricant, LPS-2 leaves
a film of oil. LPS-1 is used by most locksmiths.

--
Michael Press
 
MattyMattyChooChoo wrote:
> [I wrote]
> > It's a thumb shifter, not an STI shifter. It may not even have
> > any pawls, just a set of detents. Thumbies are fairly simple.

>
> The index finger portion of the gear shifter works fine when I reach
> down ot the read deraileur and start in a lower gear. I took the cover
> from the bottom of the gear-shift and noticed that the tooth attached
> to the thumb lever would not catch the teeth on the wheels intended to
> shift the gears.
>
> I would guess (and it may be a poor guess) that if the index finger
> trigger catches, then the cable should be okay.


Well you just made my advice moot, because you have a
Rapidfire STI shifter, not a thumb shifter. A thumb shifter
predates STI and has only one lever - rotate one way to
shift up, the other way to shift down.

The fact that the index finger lever catches does not tell
you that the cable is okay, because that lever lets cable
out and is assisted by the derailleur spring, while the thumb
(downshift) lever pulls cable in and is opposed by the
derailleur spring. If your cable is stuck somewhere or
has very high friction, the upshift lever may operate while
the downshift lever doesn't.

It is more likely that the cable got rusty while the bike was
stored than that the downshift lever rotted into nonworking
condition while stored. It could happen, but why don't you
just clean out the guts of the cable and housings before
embarking on any more shifter disassembling missions?
If that doesn't work, try to buy a set of 7 speed click shifters
on ebay (or an 8 speed, since they pull nearly the same
amount of cable per click).
 
V

Vee

Guest
[email protected] wrote:
> MattyMattyChooChoo wrote:
> > [I wrote]
> > > It's a thumb shifter, not an STI shifter. It may not even have
> > > any pawls, just a set of detents. Thumbies are fairly simple.

> >
> > The index finger portion of the gear shifter works fine when I reach
> > down ot the read deraileur and start in a lower gear. I took the cover
> > from the bottom of the gear-shift and noticed that the tooth attached
> > to the thumb lever would not catch the teeth on the wheels intended to
> > shift the gears.
> >
> > I would guess (and it may be a poor guess) that if the index finger
> > trigger catches, then the cable should be okay.

>
> Well you just made my advice moot, because you have a
> Rapidfire STI shifter, not a thumb shifter. A thumb shifter
> predates STI and has only one lever - rotate one way to
> shift up, the other way to shift down.
>
> The fact that the index finger lever catches does not tell
> you that the cable is okay, because that lever lets cable
> out and is assisted by the derailleur spring, while the thumb
> (downshift) lever pulls cable in and is opposed by the
> derailleur spring. If your cable is stuck somewhere or
> has very high friction, the upshift lever may operate while
> the downshift lever doesn't.
>
> It is more likely that the cable got rusty while the bike was
> stored than that the downshift lever rotted into nonworking
> condition while stored. It could happen, but why don't you
> just clean out the guts of the cable and housings before
> embarking on any more shifter disassembling missions?
> If that doesn't work, try to buy a set of 7 speed click shifters
> on ebay (or an 8 speed, since they pull nearly the same
> amount of cable per click).


Are we reading different threads or what? He's saying the thumb lever
is not engaging, so the problem is not the cable.

-Vee