Derailleur weirdness

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

Quoted message said:

I've built up a new frame (K2) with some DuraAce components harvested off

of

Quoted message said:

an old frame where the front end was wrecked.

I'm having a weird problem with the rear derailleur. It sets up perfectly in the stand and will do
fine on an easy to moderate-intensity ride. But

if

Quoted message said:

I get out and hammer and get out of the saddle to jam up a small hill or something, the shifting
will become all screwy over the course of the

ride.

Quoted message said:

I'll stop and I'll find the derailleur pulleys a full cog out of

alignment.

Quoted message said:

I'll turn the barrel adjuster and get things back in order. It'll be fine for a couple of days,
then suddenly the episode will repeat itself.

This has gone on for well over a month now, so it's something beyond cable stretch (which is what
my LBS claims it is). I've been a high-mileage

rider

Quoted message said:

for many years and I've never seen cable stretch anything like this.

Another theory I heard is that there was leftover paint in the cable

housing

Quoted message said:

seats on the new frame and the housing is setting farther into the seats

as

Quoted message said:

time goes on. I guess that's plausible ... but what do the experts here think?

I'm no expert and this response may prove it but, could there be enough flex in the entire bike for
a tensioned chain to pull it out of alignment?

a.

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

Quoted message said:

I've built up a new frame (K2) with some DuraAce components harvested off of an old frame where
the front end was wrecked.

I'm having a weird problem with the rear derailleur . . .

[snip]

Dear Bob,

If you're baffled and the bike shop is baffled and the problem continues . . .

Maybe the front end wasn't the only thing damaged in the wreck?

The derailleur, for example, might have some hidden crack or bend or badly twisted spring that
wouldn't be expected. Or its control lever might have crash damage that isn't obvious.

Carl Fogel

Hey Robert. I know this will sound weird but it is probably the cable housing. Either the bits from
the levers to the frame or the bit from the chainstay cable stop to the rder. I'm guessing that the
compressionless wires that run the length of the housing are moving unconrollably due to a missing
or faulty housing endcap or the plastic on the outside of the housing has split and the wires are
about to splay out. Probably the endcap. Let us know what you discover. Keith Pears

"The knack lies in learning to throw yourself
- at the ground and miss" Douglas Adams.

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

Quoted message said:

I've built up a new frame (K2) with some DuraAce components harvested off

of

Quoted message said:

an old frame where the front end was wrecked.

I'm having a weird problem with the rear derailleur. It sets up perfectly in the stand and will do
fine on an easy to moderate-intensity ride. But

if

Quoted message said:

I get out and hammer and get out of the saddle to jam up a small hill or something, the shifting
will become all screwy over the course of the

ride.

Quoted message said:

I'll stop and I'll find the derailleur pulleys a full cog out of

alignment.

Quoted message said:

I'll turn the barrel adjuster and get things back in order. It'll be fine for a couple of days,
then suddenly the episode will repeat itself.

This has gone on for well over a month now, so it's something beyond cable stretch (which is what
my LBS claims it is). I've been a high-mileage

rider

Quoted message said:

for many years and I've never seen cable stretch anything like this.

Another theory I heard is that there was leftover paint in the cable

housing

Quoted message said:

seats on the new frame and the housing is setting farther into the seats

as

Quoted message said:

time goes on. I guess that's plausible ... but what do the experts here think?

Thanks, Bob C.

Also check to be sure no helical wires in the STI housing are creeping through any of the
cable stops.

[email hidden] (Carl Fogel) wrote in message
news:<[email hidden]>...

Quoted message said:

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

Quoted message said:

I've built up a new frame (K2) with some DuraAce components harvested off of an old frame where
the front end was wrecked.

I'm having a weird problem with the rear derailleur . . .

[snip]

Dear Bob,

If you're baffled and the bike shop is baffled and the problem continues . . .

Maybe the front end wasn't the only thing damaged in the wreck?

The derailleur, for example, might have some hidden crack or bend or badly twisted spring that
wouldn't be expected. Or its control lever might have crash damage that isn't obvious.

Carl Fogel

[email hidden] (Carl Fogel) wrote in message
news:<[email hidden]>...

Quoted message said:

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

Quoted message said:

I've built up a new frame (K2) with some DuraAce components harvested off of an old frame where
the front end was wrecked.

I'm having a weird problem with the rear derailleur . . .

[snip]

Dear Bob,

Could the coiled wire of the outer cable housings have been stretched, like a spring being pulled
apart? If so, perhaps it's slowly re-compressing and requiring repeated re-tightening of your
inner cable.

Carl Fogel

Robert Chambers said:

I've built up a new frame (K2) with some DuraAce components harvested off of an old frame where
the front end was wrecked.

I'm having a weird problem with the rear derailleur. It sets up perfectly in the stand and will do
fine on an easy to moderate-intensity ride. But if I get out and hammer and get out of the saddle
to jam up a small hill or something, the shifting will become all screwy over the course of the
ride. I'll stop and I'll find the derailleur pulleys a full cog out of alignment. I'll turn the
barrel adjuster and get things back in order. It'll be fine for a couple of days, then suddenly
the episode will repeat itself.

This has gone on for well over a month now, so it's something beyond cable stretch (which is what
my LBS claims it is). I've been a high-mileage rider for many years and I've never seen cable
stretch anything like this.

cable slipping through the clamp bolt?

[email hidden] (Carl Fogel) wrote in message
news:<[email hidden]>...

Quoted message said:

[email hidden] (Carl Fogel) wrote in message
news:<[email hidden]>...

Quoted message said:

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

Quoted message said:

I've built up a new frame (K2) with some DuraAce components harvested off of an old frame
where the front end was wrecked.

I'm having a weird problem with the rear derailleur . . .

[snip]

Dear Bob,

Could the coiled wire of the outer cable housings have been stretched, like a spring being pulled
apart? If so, perhaps it's slowly re-compressing and requiring repeated re-tightening of your
inner cable.

Carl Fogel

This doesn't apply to modern "linear" gear cable housing.

What Bob's describing is somewhat like I've experienced with ill-fitting housing ferrules and old
housing. I'd replace all the housing and ferrules- if it's more than a year or two old it's probably
due to be replaced anyway.

Jeff

[email hidden] (Jeff Wills) wrote in message
news:<[email hidden]>...

Quoted message said:

This doesn't apply to modern "linear" gear cable housing.

What Bob's describing is somewhat like I've experienced with ill-fitting housing ferrules and old
housing. I'd replace all the housing and ferrules- if it's more than a year or two old it's
probably due to be replaced anyway.

Jeff

Dear Jeff,

It's hell growing old and out of date, but thanks for your kind correction--I've got to look into
these new-fangled devices!

I assume that these "linear" cable housings offer some modern advantages over "coil" housings,
but why do they need to be replaced every year or so? Is it just cheaper to replace them than to
clean them up, or does some special wear pattern limit their life-span? Do you replace the inner
cables, too?

Thanks,

Carl Fogel

(Carl Fogel) said:

I assume that these "linear" cable housings offer some modern advantages over "coil" housings,
but why do they need to be replaced every year or so? Is it just cheaper to replace them than to
clean them up, or does some special wear pattern limit their life-span? Do you replace the inner
cables, too?

The main benefit of these cable housings with linear wires rather than helical ones is that they
maintain a constant length throughout the steering arc. This is to prevent the action of swinging
the bars from affecting the centering over the gear. The down side is that they have little
compressive strength, so one must be careful to not use them for the brake cables.

They last for years just fine, being lined with a plastic tube like brake cables. Hmm, I've got some
that are at least 7 years old on one bike, and some that are 4 years old on another. There's no
deterioration in their performance. IMHO some people just like working on their bikes and replacing
stuff whether it needs it or not (nothing wrong with that, I've been known to do it myself).