A query about front derailleur alignment

Zog The Undeniable said:

For those with braze-on front derailleurs, is the front or the rear
of the cage closest to the large chainring?

I'm pretty sure mine are all with the front closest to the chainring,
but it's dark in the shed so I can't be 100% (only 99%).

Quoted message said:

http://www.peeble.com/bikes/mech2.jpg

That doesn't look right at all

--
Mike

Zog The Undeniable wrote on 14/03/2006 :

Quoted message said:

For those with braze-on front derailleurs, is the front or the rear of the
cage closest to the large chainring? In my experience the front of the cage
should contact first, since that's where Shimano stick that little
transparent 2mm gap measuring thingy, but on the frame I've just had back
from the builders, the rear of the cage is the first to scrape.

On a triple set up, the point on the mech at which the first contact
occurs tends to be further back. The design of triple changers reflects
this.

Quoted message said:

As there is
no elevation adjustment on a front mech, I suspect the hanger has been brazed
on non-parallel to the seat tube. The mech (a Shimano 1057 triple) is
designed for, and is being used with, a 52T big ring.

It certainly looks slightly out on your photos.

Quoted message said:

If it's been cocked up then it's incredibly annoying, since the fork has
already been sent back for having the wrong steerer length and for the
dropouts no longer being 100mm apart.

I don't think I'd give them my business again, if I were you.

Quoted message said:

If the frame has to go back that's
another respray and another 5 weeks (unless they pull their fingers out).

I think I'd contact the builder and let them know that you think
there's a problem. However, I'm not sure that I'd ask them to re-braze
/ re-spray.

The actual misalignment is very slight; firtsly, I'd try it out on the
road to see if it works! Really obviously misaligned mechs can actually
sometimes work perfectly well.

If there is a problem, I reckon it's worth nudging (okay, bending) the
plate slightly. You won't need to make a noticeable difference to it,
and you won't really even feel anything move very much when you do it.
It'll only take a nudge.

I spent 17 years in the specialist cycle trade, and, believe me, things
like this are regular in professional workshops. There aren't many that
go back for re-sprays, though...

--
Simon
www.simondaw.freeserve.co.uk

Zog The Undeniable said:

For those with braze-on front derailleurs, is the front or the rear of
the cage closest to the large chainring? In my experience the front
of the cage should contact first, since that's where Shimano stick
that little transparent 2mm gap measuring thingy, but on the frame
I've just had back from the builders, the rear of the cage is the
first to scrape. As there is no elevation adjustment on a front
mech, I suspect the hanger has been brazed on non-parallel to the
seat tube. The mech (a Shimano 1057 triple) is designed for, and is
being used with, a 52T big ring......

Quoted message said:

A couple of photos here (sorry, taking flash pictures of shiny objects
is a nightmare). One suggests the hanger is out of parallel, the
other shows how the mech cage is decidedly non-concentric with the
teeth of the big ring.

http://www.peeble.com/bikes/mech1.jpg
http://www.peeble.com/bikes/mech2.jpg

I think it looks wrong. All the installation instructions I've ever seen
show it tilted the other way with the top closest to the chainring.

Rather than send the frame back (though you'd be perfectly entitled to do
so), is there any option to shim the mechanism at its clamp point, using a
thin piece as a wedge to tip the changer in the required direction.

Quoted message said:

The reason for having braze-on hangers with the respray is that I've
had terrible problems with clamp-on mechs slipping and gouging the
seat tube. The cable tension on some of the modern ones is so high
that I had to practically strip the clamp bolt to get it to hold.

It might be easier to ask for a small "lump" to be fitted to the frame to
stop the band-on from moving. Or even drill the tube, fit a tiny grub screw
to act as an anti-gouge stop. I've done the latter on a cheap frame a dozen
years ago (which is so ancient and rusty, that this isn't a worry :-) ).

- Nigel

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Zog The Undeniable said:

For those with braze-on front derailleurs, is the front or the rear of
the cage closest to the large chainring?

Front, with my Campag triple braze-on and 51t big ring, but equal would be
ideal, I think.

~PB