Gear Mystery

Following on from Neil Smith's message. . .

Quoted message said:

Dear All,
both front and rear gears got stuck on the smallest rings. Re-adjusted cable
several times, with in a few miles, they were back in the smallest rings.
Couldn't see any problem with either cables but replaced them anyway. I
still end up on the smallest rings! As it affects both derailleurs and don't
think it can be their fault. It is not the cables. What is it?
Thanks,
Neil.

What sort of shifters have you got? Is what's happening that they
'click' and have clicked and stay clicked into big-ring while the mech
is creeping into smaller rings.

Unless your frame is cracked through or your shifters moving on the
handle bars the problem lies with the cable/fixing.
* You have used proper gear cable and not brake cable?
* Mark a set amount from the allen key clamp on the mech with say nail
varnish (quick dry paint) to see if the cable is slipping through the
clamp.
NB Work on one gear set at a time to avoid confusion.

--
PETER FOX Not the same since the adhesive company came unstuck
[email hidden]
2 Tees Close, Witham, Essex.
Gravity beer in Essex <http://www.eminent.demon.co.uk>

Neil Smith <[email hidden]> typed:

Quoted message said:

Dear All,
both front and rear gears got stuck on the smallest rings. Re-adjusted
cable several times, with in a few miles, they were back in the smallest
rings. Couldn't see any problem with either cables but replaced them
anyway. I still end up on the smallest rings! As it affects both
derailleurs and don't think it can be their fault. It is not the cables.
What is it?

Sounds like your shifters are slipping, not tightened up properly or you've
used the wrong cable .. it has to be gear cable not brake cable.

If your shifters are 'click' shift then maybe something's broke, but that's
unlikely with two shifters, or you've fitted cables in wrongly, so it would
appear to be a maintenance/fitting issue. Indeed, thinking about it further
after having typed this reply I'd guess that you've [1] replaced/re-adjusted
cables slightly wrongly and/or that the shifters aren't rebuilt correctly.
Indeed they may simply be worn out ... the nylon ridges on a twist-grip, for
example, don't last forever, certainly not in my experience and especially
not if you ride off-road in dusty/sandy conditions.

Could also be the cable stays loosening, but again this is unlikely that it
would happen to both derailleurs at the same time, unless there's a human
element causing problems. 😉

If they're friction shifters maybe they're not tight enough or there's no
friction area left.

Have a look and post back what sort of shifter they are, might help with a
better diagnosis, or even a pic or three .. 😉

[1] Whoever rebuilt/maintains the gear shifts.

--
Paul - [censored]

Paul - censored said:

Neil Smith <[email hidden]> typed:

Quoted message said:

Dear All,
both front and rear gears got stuck on the smallest rings. Re-adjusted
cable several times, with in a few miles, they were back in the smallest
rings. Couldn't see any problem with either cables but replaced them
anyway. I still end up on the smallest rings! As it affects both
derailleurs and don't think it can be their fault. It is not the cables.
What is it?

Sounds like your shifters are slipping, not tightened up properly or you've
used the wrong cable .. it has to be gear cable not brake cable.

If your shifters are 'click' shift then maybe something's broke, but that's
unlikely with two shifters, or you've fitted cables in wrongly, so it would
appear to be a maintenance/fitting issue. Indeed, thinking about it further
after having typed this reply I'd guess that you've [1] replaced/re-adjusted
cables slightly wrongly and/or that the shifters aren't rebuilt correctly.
Indeed they may simply be worn out ... the nylon ridges on a twist-grip, for
example, don't last forever, certainly not in my experience and especially
not if you ride off-road in dusty/sandy conditions.

Could also be the cable stays loosening, but again this is unlikely that it
would happen to both derailleurs at the same time, unless there's a human
element causing problems. 😉

If they're friction shifters maybe they're not tight enough or there's no
friction area left.

Have a look and post back what sort of shifter they are, might help with a
better diagnosis, or even a pic or three .. 😉

[1] Whoever rebuilt/maintains the gear shifts.

I'm no expert on bicycle mechanics, but on every derailleur I've ever
ridden the 'bias' is for the mechanism to move 'outwards'.

So what makes this problem so weird is that the front mech is actually
creeping *away* from the bias.

Or am I making some false assumption?

Ziggy said:

I'm no expert on bicycle mechanics, but on every derailleur I've ever
ridden the 'bias' is for the mechanism to move 'outwards'.

So what makes this problem so weird is that the front mech is actually
creeping *away* from the bias.

Or am I making some false assumption?

I think you're making a false assumption. On all the front mechs I've had
the spring pushes the mech towards the inner ring.
--
Chris

Never call a man a fool; borrow from him.

On Sun, 29 Apr 2007 08:56:29 GMT, [email hidden] (Ziggy)

Quoted message said:

On Sun, 29 Apr 2007 09:35:42 +0100, "Paul - [censored]"
<[email hidden]> wrote:

Quoted message said:

I'm no expert on bicycle mechanics, but on every derailleur I've ever
ridden the 'bias' is for the mechanism to move 'outwards'.

So what makes this problem so weird is that the front mech is actually
creeping *away* from the bias.

Or am I making some false assumption?

Falsa assumption, I'm afraid. The front will move to the small ring
(low gear) if there is no tension.

ME

Chris Slade said:

Ziggy said:

I'm no expert on bicycle mechanics, but on every derailleur I've ever
ridden the 'bias' is for the mechanism to move 'outwards'.

So what makes this problem so weird is that the front mech is actually
creeping *away* from the bias.

Or am I making some false assumption?

I think you're making a false assumption. On all the front mechs I've had
the spring pushes the mech towards the inner ring.

Yes, of course, you're correct. I *knew* there was something wrong with
how I was thinking about that. It was the same with the ones I've
ridden, but I just confused myself.

"Ziggy" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm no expert on bicycle mechanics, but on every derailleur I've ever
ridden the 'bias' is for the mechanism to move 'outwards'.

So what makes this problem so weird is that the front mech is actually
creeping *away* from the bias.

Or am I making some false assumption?

Rear derailleurs move outwards when there is no tension in the cable, but
again this puts it onto the smallest cog.

If the front derailleur is attached to the bottom bracket, make sure it is
tightened up properly because if it's loose it will waggle around when you
change gear and ultimately stick on the smallest cog.
--
peter

Cheap train tickets database
http://www.petereverett.co.uk/tickets/

Email sent to this address is generally deleted upon arrival
Visit website if you want to contact me

in message <[email hidden]>, Neil Smith

(') said:

Dear All,
both front and rear gears got stuck on the smallest rings. Re-adjusted
cable several times, with in a few miles, they were back in the smallest
rings. Couldn't see any problem with either cables but replaced them
anyway. I still end up on the smallest rings! As it affects both
derailleurs and don't think it can be their fault. It is not the cables.
What is it? Thanks,

Your cable clamp screws, on the derailleurs, are slipping. You haven't got
them done up tight enough.

If not, then some part of your cable sheathing is slipping, but I'm fairly
confident my first answer is right.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

I shall continue to be an impossible person so long as those
who are now possible remain possible -- Michael Bakunin

in message <[email hidden]>, Ziggy

(') said:

Paul - censored said:

Neil Smith <[email hidden]> typed:

Quoted message said:

Dear All,
both front and rear gears got stuck on the smallest rings. Re-adjusted
cable several times, with in a few miles, they were back in the
smallest rings. Couldn't see any problem with either cables but
replaced them anyway. I still end up on the smallest rings! As it
affects both derailleurs and don't think it can be their fault. It is
not the cables. What is it?

Sounds like your shifters are slipping, not tightened up properly or
you've used the wrong cable .. it has to be gear cable not brake cable.

If your shifters are 'click' shift then maybe something's broke, but
that's unlikely with two shifters, or you've fitted cables in wrongly, so
it would
appear to be a maintenance/fitting issue. Indeed, thinking about it
further after having typed this reply I'd guess that you've [1]
replaced/re-adjusted cables slightly wrongly and/or that the shifters
aren't rebuilt correctly. Indeed they may simply be worn out ... the
nylon ridges on a twist-grip, for example, don't last forever, certainly
not in my experience and especially not if you ride off-road in
dusty/sandy conditions.

Could also be the cable stays loosening, but again this is unlikely that
it would happen to both derailleurs at the same time, unless there's a
human
element causing problems. 😉

If they're friction shifters maybe they're not tight enough or there's no
friction area left.

Have a look and post back what sort of shifter they are, might help with
a better diagnosis, or even a pic or three .. 😉

[1] Whoever rebuilt/maintains the gear shifts.

I'm no expert on bicycle mechanics, but on every derailleur I've ever
ridden the 'bias' is for the mechanism to move 'outwards'.

So what makes this problem so weird is that the front mech is actually
creeping *away* from the bias.

Or am I making some false assumption?

Yes, you're plain wrong. The only widely used derailleur where the spring
pulls towards the big ring is the Shimano 'Rapid Rise', where both
derailleur springs pull inward. On all other commonly used derailleur
systems, the rear spring pulls outward and the front spring pulls inward -
towards the smallest ring, as the OP says.

His cables are slipping.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
Copyright (c) Simon Brooke; All rights reserved. Permission is
granted to transfer this message via UUCP or NNTP and to store it
for the purpose of archiving or further transfer. Permission is
explicitly denied to use this message as part of a 'Web Forum', or
to transfer it by HTTP.

On Sun, 29 Apr 2007 18:07:32 +0100, Simon Brooke <[email hidden]>

Quoted message said:

Yes, you're plain wrong.

Yes, I did say that several hours ago :-)

in message <[email hidden]>, Ziggy

(') said:

On Sun, 29 Apr 2007 18:07:32 +0100, Simon Brooke <[email hidden]>

Quoted message said:

Yes, you're plain wrong.

Yes, I did say that several hours ago :-)

Sorry. Been out marshalling the SXC all day (and I have a bad habit of
replying to posts as I come to them, not reading the whole thread first).

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; L'etat c'est moi -- Louis XVI
;; I... we... the Government -- Tony Blair

Both gears are shimano, the gear levers are thumbshifters, one cable is
definitely gear, I'll replace the other new cable just to be 100% sure that
it is a gear cable and if I tightened the nuts anymore I would risk
stripping the thread.

"Simon Brooke" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

in message <[email hidden]>, Neil Smith

(') said:

Dear All,
both front and rear gears got stuck on the smallest rings. Re-adjusted
cable several times, with in a few miles, they were back in the smallest
rings. Couldn't see any problem with either cables but replaced them
anyway. I still end up on the smallest rings! As it affects both
derailleurs and don't think it can be their fault. It is not the cables.
What is it? Thanks,

Your cable clamp screws, on the derailleurs, are slipping. You haven't got
them done up tight enough.

If not, then some part of your cable sheathing is slipping, but I'm fairly
confident my first answer is right.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

I shall continue to be an impossible person so long as those
who are now possible remain possible -- Michael Bakunin

O.k. replaced gear cable for the second time. If by co-incidence both
de-railleurs are gone, how do you tell?
"Neil Smith" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Both gears are shimano, the gear levers are thumbshifters, one cable is
definitely gear, I'll replace the other new cable just to be 100% sure
that it is a gear cable and if I tightened the nuts anymore I would risk
stripping the thread.

"Simon Brooke" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

in message <[email hidden]>, Neil Smith

(') said:

Dear All,
both front and rear gears got stuck on the smallest rings. Re-adjusted
cable several times, with in a few miles, they were back in the smallest
rings. Couldn't see any problem with either cables but replaced them
anyway. I still end up on the smallest rings! As it affects both
derailleurs and don't think it can be their fault. It is not the cables.
What is it? Thanks,

Your cable clamp screws, on the derailleurs, are slipping. You haven't
got
them done up tight enough.

If not, then some part of your cable sheathing is slipping, but I'm
fairly
confident my first answer is right.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

I shall continue to be an impossible person so long as those
who are now possible remain possible -- Michael Bakunin

in message <[email hidden]>, Neil Smith

(') said:

O.k. replaced gear cable for the second time. If by co-incidence both
de-railleurs are gone, how do you tell?

What do you mean, 'gone'? What derailleurs die of is

(i) pivots so worn that the movement of the pantograph is sloppy and it's
easy to twist the cage out of line;

(ii) the chain wearing through one side of the cage;

(iii) the spring becoming too weak to reliably return the derailleur to the
relaxed position.

They don't die of anything else that I can think of.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

Hobbit ringleader gives Sauron One in the Eye.

Simon Brooke said:

in message <[email hidden]>, Neil Smith

(') said:

O.k. replaced gear cable for the second time. If by co-incidence both
de-railleurs are gone, how do you tell?

What do you mean, 'gone'? What derailleurs die of is

(i) pivots so worn that the movement of the pantograph is sloppy and it's
easy to twist the cage out of line;

(ii) the chain wearing through one side of the cage;

Especially on front derailleurs. Don't know if it's called the "cage"
but they do eventually wear through where they push the chain up onto
the big ring.

Quoted message said:

(iii) the spring becoming too weak to reliably return the derailleur to the
relaxed position.

I think that shouldn't happen in theory. A spring should go on springing
until ultimately one day it breaks altogether, but that might take a
very long time.

I wonder if this symptom might really be caused by a lot of grime
clogging things causing resistance in the mechanism. It looks like the
spring's got weaker, but in fact it's pushing with the same force, just
against more crud.

in message <[email hidden]>, Ben C

(') said:

Quoted message said:

(iii) the spring becoming too weak to reliably return the derailleur to
the relaxed position.

I think that shouldn't happen in theory. A spring should go on springing
until ultimately one day it breaks altogether, but that might take a
very long time.

I wonder if this symptom might really be caused by a lot of grime
clogging things causing resistance in the mechanism. It looks like the
spring's got weaker, but in fact it's pushing with the same force, just
against more crud.

Nah. The one I'm thinking about was a beautiful - top quality - Mavic on a
1980s time trial bike I was working on. We cleaned up that derailleur and
regreased all the pivots 'till it was like new, but the spring was
decidedly weak. It worked... but if you'd been able to replace it you
would have.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; in faecibus sapiens rheum propagabit

Simon Brooke said:

What do you mean, 'gone'? What derailleurs die of is

<snip>

Quoted message said:

They don't die of anything else that I can think of.

Don't forget shifting into the spokes.

--
Danny Colyer <URL:http://www.colyer.plus.com/danny/>
Reply address is valid, but that on my website is checked more often
"Daddy, put that down. Daddy, put that down. Daddy, put that down.
Daddy, why did you put that down?" - Charlie Colyer, age 2

In news:[email hidden],
Danny Colyer <[email hidden]> tweaked the Babbage-Engine to tell
us:

Quoted message said:

Simon Brooke said:

What do you mean, 'gone'? What derailleurs die of is <snip>
They don't die of anything else that I can think of.

Don't forget shifting into the spokes.

Ingesting a plastic bag, likewise with a chunk of tension-sheet and smiting
the kerb have done for three of mine.

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Funny... You don't /look/ like Martha and the Vandellas!

Mystery solved. I took it into a bike shop and he immediately pointed out
that the cable supports were slipping down the tube. It was a case of not
being able to solve a problem because you are staring to hard at the wrong
part of it.
I now have the problem of how to loosen a rusted bolt. I hope the light oil
works.
Thanks for your suggestions
Neil
"Simon Brooke" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

in message <[email hidden]>, Neil Smith

(') said:

O.k. replaced gear cable for the second time. If by co-incidence both
de-railleurs are gone, how do you tell?

What do you mean, 'gone'? What derailleurs die of is

(i) pivots so worn that the movement of the pantograph is sloppy and it's
easy to twist the cage out of line;

(ii) the chain wearing through one side of the cage;

(iii) the spring becoming too weak to reliably return the derailleur to
the
relaxed position.

They don't die of anything else that I can think of.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

Hobbit ringleader gives Sauron One in the Eye.