Front Derailleur Overshift of Large Chainring

[gary jacobson]

I just can't nail this problem.

TA Zephyr crank with 10 speed 46/34 rings and Campy 10 double front
deraillueur. I've used Sachs compact, Campy triple front, and 105 double-
same problem.
Chainline and crank spacing is set up so that inner ring lines up with bb
lockring when viewed from above. 2 mm between bottom of derailleur cage and
top of chainring. I can't adjust against overshifting with the limit screw.
If I turn the screw enough so there's no overshift then the chain won't go
into big ring. My thoughts are to either bend the front of the outer
drailleur in to prevent overshift, or bend the inner plate in and see if it
will trigger a shift with the limit screw set at the point where it wouldn't
shift before that tweak.

Interesting that the Sachs compact front seemed to do the poorest job of
matching profile of 46 chainring.

My goal for this summer is to get this riding season to get this to work. In
the past if it worked, it would only stay in tune for a few months. Yes I
have threadlock on adjusting screw.

Thanks.

Gary Jacobson
Rosendale, NY

 

[Qui si parla Campagnolo]

gary jacobson wrote:
> I just can't nail this problem.
>
> TA Zephyr crank with 10 speed 46/34 rings and Campy 10 double front
> deraillueur. I've used Sachs compact, Campy triple front, and 105 double-
> same problem.
> Chainline and crank spacing is set up so that inner ring lines up with bb
> lockring when viewed from above. 2 mm between bottom of derailleur cage and
> top of chainring. I can't adjust against overshifting with the limit screw.
> If I turn the screw enough so there's no overshift then the chain won't go
> into big ring. My thoughts are to either bend the front of the outer
> drailleur in to prevent overshift, or bend the inner plate in and see if it
> will trigger a shift with the limit screw set at the point where it wouldn't
> shift before that tweak.
>
> Interesting that the Sachs compact front seemed to do the poorest job of
> matching profile of 46 chainring.
>
> My goal for this summer is to get this riding season to get this to work. In
> the past if it worked, it would only stay in tune for a few months. Yes I
> have threadlock on adjusting screw.
>
> Thanks.
>
> Gary Jacobson
> Rosendale, NY

Look where the front der contacts the chain when moving it up and bend
that a wee bit towards the big ring. It is where they locate the pins
for these rings that makes it tough to shift. I've seen the same thing
with some FSA cranks, Compact.

You can also try to move the rings arond to match a Campag crank
location of pins as well.

 

[gary jacobson]

"Qui si parla Campagnolo" <[email protected]> wrote in message
news:[email protected]...

> You can also try to move the rings arond to match a Campag crank
> location of pins as well.

This brings up another question. Why/how does it matter where the pick up
pins are on the chainwheel in relation to crank arm?
Or are you talking about relation of pick up pins on both chain wheels.
(Does the small one have them?)

Thanks.

Gary Jacobson
Rosendale, NY