road derailleur for MTB frame

"Richard Goodman" <[email hidden]> wrote in message
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Quoted message said:

I've got a MTB frame that I want to build up with road components (never mind why, I've got the
frame so let's start from there). This means a triple road chainset (52T), Shimano STI levers, and
top-pull cable routing. It needs a band on front mech (31.8mm). I could use an adaptor for
bottom-pull mechs.. but which front mech is most likely to work? It seems one of the issues is
seat stay angle - but MTB mechs tend to be design for compact chainsets with 42T max (and would
they work with the STI lever?) There seem to be some 'hybrid' mechs, but still limited to 48T max.
Then there are the road mechs, but the seat tube angle, it seems, might not be ideal for them.

Any suggestions as to a front mech model that might best fit this situation?

If you're using a road crank/chainrings, use a road fd.

rich-<< I've got a MTB frame that I want to build up with road components (never mind why, I've got
the frame so let's start from there). This means a triple road chainset (52T), Shimano STI levers,
and top-pull cable routing. It needs a band on front mech (31.8mm). I could use an adaptor for
bottom-pull mechs.. but which front mech is most likely to work? >><BR><BR>

No top pull, MTB type front der will really work with STI and a triple. The arms of the der are not
compatible with STI.

I would use the road mech, the e-clamp pulley system and use a bottom pull front der, which
will work.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali costruite eccezionalmente bene"

"Peter Cole" <[email hidden]> wrote in message
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Quoted message said:

If you're using a road crank/chainrings, use a road fd.

This is what I'm inclined to think, although my LBS seemed to think a mtb fder would be the
better bet.

The issue seems to come down to which is the most critical dimension - chainstay angle or max teeth
- Shimano's tech docs for mtb fders say they're designed for chainstay angles (presumably wrt to the
seat tube?) of 63-66 deg and max teeth of ~42 -44; while their road fders are designed for chainstay
angles of 66 - 69 deg and 52 teeth max? I'm trying to use a frame which presumably comes within the
mtb chainstay angle range and the max teeth of a road chainset.

I'm inclined to think it must be max teeth, which makes a road fder right. But even then there are
different makes and models - is there, for example, a top-pull, 9 speed, 31.8mm band on road fder,
compatible with Shimano drop bar STI levers out there somewhere, which is also made for mtb
chainstay angles, or am I going to have to use an adaptor with a bottom pull one, and hope that the
chainstay angle isn't too far out of range or too significant a factor?

Rich

"Qui si parla Campagnolo" <[email hidden]> wrote in message
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Quoted message said:

No top pull, MTB type front der will really work with STI and a triple.

The

Quoted message said:

arms of the der are not compatible with STI.

Ah, I thought I'd heard something about mtb fders not working properly with road STI, quite apart
from the other issues.

Quoted message said:

I would use the road mech, the e-clamp pulley system and use a bottom pull front der, which
will work.

Thanks, that's what I'm going to do.

Rich

Richard Goodman said:

The issue seems to come down to which is the most critical dimension - chainstay angle or max
teeth - Shimano's tech docs for mtb fders say

You know, as I understand, those are both functions of the shape and size of the cage. What about
fabricating a new cage, or just whacking an existing cage of the right size into the right shape?

Quoted message said:

Rich

--
Rick Onanian