triple front derailleur question

Joe Dewberry said:

Hi,

What is the mechanical/technical difference between a triple and double
front derailleur? I happened to get ahold of a real gem of a bike but
it's a triple...don't need/want triple. Trying to get to double at
lowest cost w/out compromising performance.

--
Joe

Longer, wider cage, no dragging of the chain when in small ring, longer
arms for longer, farther travel per cable pull to get all the way to
the outer ring.

In article <[email hidden]>,

Joe Dewberry said:

Hi,

What is the mechanical/technical difference between a triple and double
front derailleur? I happened to get ahold of a real gem of a bike but
it's a triple...don't need/want triple. Trying to get to double at
lowest cost w/out compromising performance.

--
Joe

The cheapest way would be to not use the inner ring. No cost!

Your shifters are designed to move the FD cage that exter distance and
you could drop the chain often.

HTH

On 7 Sep 2006 05:36:16 -0700, "Joe Dewberry" <[email hidden]>

Quoted message said:

Hi,

What is the mechanical/technical difference between a triple and double
front derailleur? I happened to get ahold of a real gem of a bike but
it's a triple...don't need/want triple. Trying to get to double at
lowest cost w/out compromising performance.

Are you racing this bike?
Do you need the weight savings?
Afraid that a triple will damage your street cred?

If the answer to the three above questions is no, then leave the
triple. You can go with a close ratio cassette, and use the small ring
only if/when needed.

I'm assuming that the bike in question is a road bike, here are two
examples of modern day front derailleurs.

Double:
http://www.nashbar.com/nashbar_photos/medium/SH-FD5501.gif

Triple:
http://www.nashbar.com/nashbar_photos/medium/SH-FD5503.gif

Unfortunately the pics aren't that helpful, but take a look.

Life is Good!
Jeff

Joe Dewberry said:

Hi,

What is the mechanical/technical difference between a triple and double
front derailleur? I happened to get ahold of a real gem of a bike but
it's a triple...don't need/want triple. Trying to get to double at
lowest cost w/out compromising performance.

If you want to, you can remove the inner ring and reset the FD limit
screw. Instant double. Or, you can leave the inner ring in place and
take Jeff Starr's excellent advice regarding triples and a close ratio
cassette. And keep in mind that the inner ring and the bolts holding it
in place only weigh about 4 ounces.

H M Leary said:

In article <[email hidden]>,

Joe Dewberry said:

Hi,

What is the mechanical/technical difference between a triple and double
front derailleur? I happened to get ahold of a real gem of a bike but
it's a triple...don't need/want triple. Trying to get to double at
lowest cost w/out compromising performance.

--
Joe

The cheapest way would be to not use the inner ring. No cost!

Your shifters are designed to move the FD cage that exter distance and
you could drop the chain often.

Well, not if you reset the FD limit screw.

Quoted message said:

HTH

Joe Dewberry said:

What is the mechanical/technical difference between a triple and double
front derailleur?

One minor difference: triples have a deeper inner plate so they require
a bigger difference in size between the middle and big chainrings than
a double requires between its chainrings.

- Simon

sodaquad said:

Joe Dewberry said:

What is the mechanical/technical difference between a triple and double
front derailleur?

One minor difference: triples have a deeper inner plate so they require
a bigger difference in size between the middle and big chainrings than
a double requires between its chainrings.

That ain't necessarily so. Even if you are talking about half-step
gearing, there have been half step capable FDs (e.g., the Shimano
FD-M735, 650 and 550) for use in a "half step plus granny" setup. In
the case the OP is asking about, I'm pretty sure we're looking at
crossover gearing, so we can probably expect a 10T (or more) difference
in the factory setup.

Quoted message said:

That ain't necessarily so. Even if you are talking about half-step
gearing, there have been half step capable FDs (e.g., the Shimano
FD-M735, 650 and 550) for use in a "half step plus granny" setup.

That's interesting. I've been looking for a FD that can do this. My
current setup is 24-36-48 with an LX (M581) and I'd like to close the
gap between middle and top just a little.

sodaquad said:

Quoted message said:

That ain't necessarily so. Even if you are talking about half-step
gearing, there have been half step capable FDs (e.g., the Shimano
FD-M735, 650 and 550) for use in a "half step plus granny" setup.

That's interesting. I've been looking for a FD that can do this. My
current setup is 24-36-48 with an LX (M581) and I'd like to close the
gap between middle and top just a little.

How close do you want the big and middle rings to be?

Quoted message said:

Quoted message said:

That's interesting. I've been looking for a FD that can do this. My
current setup is 24-36-48 with an LX (M581) and I'd like to close the
gap between middle and top just a little.

How close do you want the big and middle rings to be?

Just a smidge. 24-38-48 perhaps. Or 24-36-46 and use smaller sprockets
at the back.

My original idea was to keep it wide at the front and narrow at the
back to minimise overlap. Looked good on paper, but I find that I don't
use the middle ring very much, it tops out too soon. Of course it could
be that I'm taking the Shimano figures too seriously.