Shimano LeTech Front Der: Adjustment?

I'm getting too much of this: http://tinyurl.com/ycl3qyw

The thing worked 100% at some time in it's life, but right here,
right now I can't get it to shift reliably to the big ring. Maybe
40% good shifts, 60% chain gets dropped to the outside.

Also, when the cable tension is adjusted tight enough so that I
can shift to the smallest ring, there isn't enough movement to
even begin to shift to the largest ring.

Der travel is limited to just enough for the outer ring to pick
up the chain. Giving it more does not seem to help.

I'm thinking one of these:

- Worn chain ring

- Some artifact of using a BioPace ring

- I'm doing something basically wrong.


Comments?
--
PeteCresswell

Per (PeteCresswell):
Giving it more does not seem to help.

I should add:

- Cage height is just barely enough to clear the big ring
at it's wide point - maybe 3-5mm

- Chain wear is within allowable limit per Rohloff's little tool.
--
PeteCresswell

(PeteCresswell) wrote:
I'm getting too much of this: http://tinyurl.com/ycl3qyw

The thing worked 100% at some time in it's life, but right here,
right now I can't get it to shift reliably to the big ring. Maybe
40% good shifts, 60% chain gets dropped to the outside.

Also, when the cable tension is adjusted tight enough so that I
can shift to the smallest ring, there isn't enough movement to
even begin to shift to the largest ring.

That's a SunTour, not Shimano FD yah got there. ISTR SunTours needing
lots of cable travel, so if you're using Shimano shift levers, possibly
they aren't pulling enough cable. Just a wild guess.

I'm sure that BioPace ring isn't helping you. The few bikes I set up
with BioPace, the FD was tough to position/adjust.

If it used to work right with /these/ parts, the above doesn't fit.
Maybe a fraying cable?

Could be too that the FD is shot somehow. It doesn't look like the cage
fits very closely to your rings.

Good luck,

Mark J.

On Oct 2, 7:59*pm, "(PeteCresswell)" wrote:
Per (PeteCresswell):

Giving it more does not seem to help.

I should add:

- Cage height is just barely enough to clear the big ring
* at it's wide point - maybe 3-5mm

- Chain wear is within allowable limit per Rohloff's little tool.

Sprocket teeth look good. Chain looks as if it's twisting. A new
basic chain without sideways slop may help. Bring the derailler mount
down so that the chain will only just unshift from the big ring, with
elliptical ring, finding the optimum height may be quite a bit of
trial and error. Make sure the inner blade of the fork stays parallel
to the outer ring during the shift. Re-profiling the outer fork so
that it suits the ring size better, will permit a lower mounting point
for the mech allowing the inner plate to work closer to the middle
ring so encouraging the shift without resorting to overthrow. You
will only be able to take a little off the lower front edge of the
outer fork, but it may be enough to make the shift satisfactory. The
alternative is to junk the mech and replace with a more suitable,
which might not be quite as suitable as expected. See Nate's postings.

I've been having a similar issue with a Campy Record FD (circa 2003)
shifting onto the big ring of a FSA compact 50tooth Gossamer crank.
Chain is newish KMC 10sp. When shifting onto the big ring the FD
plate almost always seems to push the chain too far and it kind of
runs on the outside of the ring before, if I'm lucky, falling into
place.

Rapid or under-power shifts often throw the chain. The limit is set
such that jamming the FD brifter will just barely get an upshift. If
the limit is set as much as an 1/8 turn further out, I'll throw the
chain and an 1/8th further in and it won't shift. I've played with
all the variables and have settled with the standard setup which still
does not work well, ie: FD plate is 1 penny's width above the teeth,
outer FD plate is parallel to the ring.

It might have something to do with the compact 50 vs. the 53 the FD
was designed for. Can anyone suggest which variable is most critical
here - possible the angle of the FD plate? Can I bend one of the
outer guide in some way to cause a more gradual shift onto the ring?
It seems the hair-trigger range of my limit screw is not acceptable.
The triples on my MTBs upshift in any condition with NO finicky
behaviour.

Thanks,

Chris

On Oct 3, 7:00*pm, "
wrote:
I've been having a similar issue with a Campy Record FD (circa 2003)
shifting onto the big ring of a FSA compact 50tooth Gossamer crank.
Chain is newish KMC 10sp. *When shifting onto the big ring the FD
plate almost always seems to push the chain too far and it kind of
runs on the outside of the ring before, if I'm lucky, falling into
place.

Rapid or under-power shifts often throw the chain. *The limit is set
such that jamming the FD brifter will just barely get an upshift. *If
the limit is set as much as an 1/8 turn further out, I'll throw the
chain and an 1/8th further in and it won't shift. *I've played with
all the variables and have settled with the standard setup which still
does not work well, ie: FD plate is 1 penny's width above the teeth,
outer FD plate is parallel to the ring.

It might have something to do with the compact 50 vs. the 53 the FD
was designed for. *Can anyone suggest which variable is most critical
here - possible the angle of the FD plate? *Can I bend one of the
outer guide in some way to cause a more gradual shift onto the ring?
It seems the hair-trigger range of my limit screw is not acceptable.
The triples on my MTBs upshift in any condition with NO finicky
behaviour.

Squeeze the derailler fork together. This is most critical at the
front, where the chain is located for the big ring, it need not be an
issue either way at the rear. You may get away with closing the fork
with the chain in place, this will save you overdoing it. The most
suitable tool is probably self locking pliers.