New Front Derailer not shifting to big ring of new Compact Cranks

Maddening. I can't get my front derailer to reliably shift on my
compact cranks. Shifting to the small ring always works. Shifting to
the big ring works intermittently. Once it stops working, it won't
work for a while (several minutes). Then, surprisingly, it will start
working again. It does not seem to matter which cog the chain is on.
When it fails to shift, the failure is due to the cage not moving far
enough to the right (outside). The chain rubs on the inner plate of
the cage, but is never "grabbed" by the big ring to complete the shift.
I have re-tuned it on the repair stand numerous times, only to have it
fail again and again on the road. The cable is old (and therefore
stretched). The cable runs over the little dog at the cable attachment
place (and therefore gives the greatest swing to the derailer). I have
cleaned the cable guide under the BB. I have lightly oiled the cable
at the cable guide. The front derailer clears the big ring by 1 mm. I
have had to set the cage to angle slightly to the outside to get the
front to shift. (My guess is that with the braze-on, this is the
setting that keeps getting lost. The problem with that hypothesis is
that the shifting will, after a time, start to work again.) The curve
of the cage does not match the curve of the big ring (it is less
curved).

Here is my setup:
FSA Energy compact cranks, 50/34
FSA Platinum BB
Campy Centaur CT (compact) front derailer, braze on
Mavic 10S chain
Campy Athena shifter
Cervelo Soloist 2004 frame

The FSA BB sticks out on the drive side about 2 mm (my old Campy Record
BB did not stick out at all). I don't know that the rings stick out
any further (I didn't measure them).

Any help is greatly appreciated. Having to stop to manually shift from
one ring to the other is no fun.

Thanks!

Kirby.

kirby wrote:
Maddening. I can't get my front derailer to reliably shift on my
compact cranks. Shifting to the small ring always works. Shifting to
the big ring works intermittently. Once it stops working, it won't
work for a while (several minutes). Then, surprisingly, it will start
working again.
Here is my setup:
FSA Energy compact cranks, 50/34
FSA Platinum BB
Campy Centaur CT (compact) front derailer, braze on
Mavic 10S chain
Campy Athena shifter
Cervelo Soloist 2004 frame

The FSA BB sticks out on the drive side about 2 mm (my old Campy Record
BB did not stick out at all). I don't know that the rings stick out
any further (I didn't measure them).

Any help is greatly appreciated. Having to stop to manually shift from
one ring to the other is no fun.

Thanks!

Kirby.

108mm BB spindle?

Outer cage of the front der parallel to the chain when in smallest cog
and big ring?

Does the arc of the front der cage follow the arc of the chainring?

I'm guessing it is associated with number three. Put something into the
vnbrazeon tab and 'GENTLY' bend it( I'm thinking aft) until the front
der cage follows the arc of the chainring.

If all else fails, use a standard front der. IME, this works better
anyway.

On 30 Jun 2005 05:06:52 -0700, "kirby"
wrote:

Campy Centaur CT (compact) front derailer, braze on

Get a regular Campy front derailleur. This particular derailleur in a
braze is crap. The design is optimized to protect the chain from
dropping inside the 34. It expects the pickup pins on the chainring
to be in an exact place and, evidently, the pins on FSA and other
chainrings aren't there. If you notice, the front cage doesn't even
follow the contour of the 50t ring with its tail sticking up. Campy
regular front derailleurs work fine and do Shimanos. If you want a
compact specific, the IRD works ok too.

108mm BB spindle?

I think so. It is sold as "BSC 108". I have not measured it.

Outer cage of the front der parallel to the chain when in smallest cog
and big ring?

No. I *must* angle the cage out a little more (inner cage parallel to
ring) in order to have it shift small to big at all. Parallel, or
slightly inwards-towards-the-back, and it it won't shift small to big.

Does the arc of the front der cage follow the arc of the chainring?

With the cage as close to the 50T ring as possible at 12:00, the gap
widens to quite a bit at 10:00. The ring is much more curved than the
cage. That the compact specific cage is not curved to match a 50T ring
is odd. If it did match, I am sure it would shift.

I'm guessing it is associated with number three. Put something into the
vnbrazeon tab and 'GENTLY' bend it( I'm thinking aft) until the front
der cage follows the arc of the chainring.

I would have to rotate it down. The braze-on tab is 1" long, and is
brazed along it's entire length. I don't think I can bend it. Moving
it so that the cage curve matches and follows the ring curve would
probably work.


If all else fails, use a standard front der. IME, this works better
anyway.

I went with the Campy CT front der. to solve a problem I was having
with dropping the chain inside when shifting big to little. I think I
picked that tidbit ("Use a Campy compact front der") in a long thread
here. Please see my other response in this thread.

Thanks for your response.

Thanks for your reply.

Get a regular Campy front derailleur. This particular derailleur in a
braze is crap. The design is optimized to protect the chain from
dropping inside the 34. It expects the pickup pins on the chainring
to be in an exact place and, evidently, the pins on FSA and other
chainrings aren't there. If you notice, the front cage doesn't even
follow the contour of the 50t ring with its tail sticking up.

I used my old Campy front derailer (Chorus or Record, I'm not home
right now) and suffered regular chain-dropping inside when shifting big
to little. In one thread here it was highly recommended to go with the
Campy compact front der. I am more than happy to go back to the
regular front der (I just want it to work reliably).

The Cervelo Soloist has what is effectively an airfoil-shaped seat
tube. Is there ANY anti-chain-suck device which I can mount to this
irregularly shaped tube?

Thanks again.

Kirby.

It expects the pickup pins on the chainring
to be in an exact place and, evidently, the pins on FSA and other
chainrings aren't there.

From observing how it (doesn't) work, this seems to be exactly the
problem.

On Thu, 30 Jun 2005 19:57:01 -0700, kirby wrote:

I used my old Campy front derailer (Chorus or Record, I'm not home
right now) and suffered regular chain-dropping inside when shifting big
to little.

A cheap chain-watcher will take care of this.

In one thread here it was highly recommended to go with the
Campy compact front der. I am more than happy to go back to the
regular front der (I just want it to work reliably).

The Cervelo Soloist has what is effectively an airfoil-shaped seat
tube. Is there ANY anti-chain-suck device which I can mount to this
irregularly shaped tube?

Thanks again.

Kirby.

--

David L. Johnson

__o | And though I have the gift of prophecy, and understand all
_`\(,_ | mysteries, and all knowledge; and though I have all faith, so
(_)/ (_) | that I could remove mountains, and have not charity, I am
nothing. [1 Corinth. 13:2]

A cheap chain-watcher will take care of this.

They all seem to require a round or roundish tube to mount them. Is
there one designed for an irregular tube, or a method of mounting one
of the available ones to such a tube. My frame is a Cervélo Soloist:
the seat tube has an airfoil cross-section. Thanks!

kirby wrote:


I'm guessing it is associated with number three. Put something into the
vnbrazeon tab and 'GENTLY' bend it( I'm thinking aft) until the front
der cage follows the arc of the chainring.

I would have to rotate it down. The braze-on tab is 1" long, and is
brazed along it's entire length. I don't think I can bend it. Moving
it so that the cage curve matches and follows the ring curve would
probably work.



Yes you can and the if the tail of the front der is too high, the
'bump' on the front der designed to grab the chain and put it onto the
big ring is too high.

It has nothing to do with placement of pickup pins or ramps but if the
chain while on the small ring stays below that bump on the front der.
gently bend the entire tab back to et the tial of the front der down. A
requirement since the seattube cannot accept a chain watcher.

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In article .com,
kirby wrote:
A cheap chain-watcher will take care of this.

They all seem to require a round or roundish tube to mount them. Is
there one designed for an irregular tube, or a method of mounting one
of the available ones to such a tube. My frame is a Cervélo Soloist:
the seat tube has an airfoil cross-section. Thanks!


_ 3rd Eye with zip ties instead of a steel clamp ?

http://store.airbomb.com/ItemDesc.asp?IC=CH2052

I have no idea if this would really work or not.

_ The larger question of why you are using a compact crank on a
TT bike puzzles me. But each to his own I guess.

_ Booker C. Bense


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