Mountain FDs that hug the seatpost more closely?

On 9/26/2008 5:41 PM Ed Pirrero wrote:

On Sep 25, 3:44 pm, Mike Rocket J Squirrel
wrote:
On 9/24/2008 9:28 PM Mike Rocket J Squirrel wrote:





On 9/24/2008 7:43 PM Hank wrote:
On Sep 24, 4:23 pm, Mike Rocket J Squirrel
wrote:
IN MY QUEST to narrow the tread, the "Q" factor, on my old Specialized
Sirrus while simultaneously lowering the gears, I have replaced the BB
with a 107 mm UN54, and mounted some triple off my mountain bike. The
cranks are 175 mm and I'm of a shorter race, so I like the 165 mm that I
use on my road bike.
So today I received an Acera FC-M341 crankset w/ 170 mm arms. This set has
a nice 22t inner, which I like. However, when the two cranks are set on a
flat surface, it's obvious that these new cranks are bent out farther than
the old, by almost a cm--which would make for a very wide Q factor, which
hurts my knees.
Even so, I figured I'd mount them on the bike and see how it all works.
First I had to modify the inner chain ring so it would not scrape the BB
shell on account of that measly 107 mm spindle -- the BB ends up actually
going inside the inner ring. I know I could use a longer spindle, but
since this crankset already has quite wide Q, this could be a Good Thing
and compensate for that. The short spindle works well with the other crankset.
Once the inner ring was modified, the crank mounted well.
However, the FD doesn't know what to do with chain rings so close to the
seat tube [was "seatpost"]. Even with the LOW stop screw backed all the way out, the cage
doesn't swing inward enough to drop the chain onto the inner ring.
Funny that the unknown 175 mm mountain triple, which doesn't have such a
wide Q factor, places the rings far enough away from the seat tube [was "seatpost"] that the
FD can deal with them.
ANYWAY, The FD is a Nexave. I also have an Acera and it doesn't look to
come any closer to the seat tube [was "seatpost"] than the Nexave.
So, are there any mountain-type FDs that come closer to the seat tube [was "seatpost"] than
these two? Inquiring minds want to know.
(I have coming on the way a Sugino XD300 crankset in 165 mm. Dunno if I'm
going to have the same issue with that puppy.)
--
Mike "Rocket J Squirrel"
There's a very important piece of information missing here - just how
far is that small ring from the seat tube?
It's tough to make suggestions without knowing how close is close
enough.
Picky, picky, picky. But right. I'll measure it in the a.m. and get back.
Okay, I'm back.

With the Acera FC-M341 mounted on the 107 mm spindle, the outer face of
the inner ring is 19.6 mm from the seat tube (I know I said "seatpost" in
my OP, I'm not as smart as I wish I was!). The ring looks to be about 2 mm
thick, give or take, so that puts the centerline of the ring 17.6 mm from
the seat tube.

The O.D. of the seat tube is 32.3 (or so) mm.

So, for those of you who showed up late to class, the question is whether
there is a mtb FD that can swing close enough to the seat tube to handle
an inner ring that close to the tube? Neither my Nexave nor my Acera can.

BTW, pm has suggested that "any old mtb derailleur in a bottom swing style
should work better."

Bottom-swing MTB FDs can be found on eBay.

Even in your seat tube diameter.

You can get those suckers to adjust right up next to the seat tube.

E.P.

Thanks, Ed.

Problem is, I don't know enough about the various models of FDs offered on
eBay to know what I'm looking at.

I guess my basic requirements a Bottom-swing, bottom-pull mtb FD that
will fit a 32.3 (or so) mm seat tube.

Maybe someone who know about these things can make a recommendation or
two? I prefer the Buy It Now option as I am terrible at guessing whether
the Price is Right or not.

--
Mike "Rocket J Squirrel"

On 9/26/2008 5:48 PM Ed Pirrero wrote:

On Sep 26, 1:22 pm, Mike Rocket J Squirrel
wrote:
On 9/25/2008 3:44 PM Mike Rocket J Squirrel wrote:





On 9/24/2008 9:28 PM Mike Rocket J Squirrel wrote:
On 9/24/2008 7:43 PM Hank wrote:
On Sep 24, 4:23 pm, Mike Rocket J Squirrel
wrote:
IN MY QUEST to narrow the tread, the "Q" factor, on my old Specialized
Sirrus while simultaneously lowering the gears, I have replaced the BB
with a 107 mm UN54, and mounted some triple off my mountain bike. The
cranks are 175 mm and I'm of a shorter race, so I like the 165 mm that I
use on my road bike.
So today I received an Acera FC-M341 crankset w/ 170 mm arms. This set has
a nice 22t inner, which I like. However, when the two cranks are set on a
flat surface, it's obvious that these new cranks are bent out farther than
the old, by almost a cm--which would make for a very wide Q factor, which
hurts my knees.
Even so, I figured I'd mount them on the bike and see how it all works.
First I had to modify the inner chain ring so it would not scrape the BB
shell on account of that measly 107 mm spindle -- the BB ends up actually
going inside the inner ring. I know I could use a longer spindle, but
since this crankset already has quite wide Q, this could be a Good Thing
and compensate for that. The short spindle works well with the other crankset.
Once the inner ring was modified, the crank mounted well.
However, the FD doesn't know what to do with chain rings so close to the
seat tube [was "seatpost"]. Even with the LOW stop screw backed all the way out, the cage
doesn't swing inward enough to drop the chain onto the inner ring.
Funny that the unknown 175 mm mountain triple, which doesn't have such a
wide Q factor, places the rings far enough away from the seat tube [was "seatpost"] that the
FD can deal with them.
ANYWAY, The FD is a Nexave. I also have an Acera and it doesn't look to
come any closer to the seat tube [was "seatpost"] than the Nexave.
So, are there any mountain-type FDs that come closer to the seat tube [was "seatpost"] than
these two? Inquiring minds want to know.
(I have coming on the way a Sugino XD300 crankset in 165 mm. Dunno if I'm
going to have the same issue with that puppy.)
--
Mike "Rocket J Squirrel"
There's a very important piece of information missing here - just how
far is that small ring from the seat tube?
It's tough to make suggestions without knowing how close is close
enough.
Picky, picky, picky. But right. I'll measure it in the a.m. and get back.
Okay, I'm back.
With the Acera FC-M341 mounted on the 107 mm spindle, the outer face of
the inner ring is 19.6 mm from the seat tube (I know I said "seatpost" in
my OP, I'm not as smart as I wish I was!). The ring looks to be about 2 mm
thick, give or take, so that puts the centerline of the ring 17.6 mm from
the seat tube.
The O.D. of the seat tube is 32.3 (or so) mm.
So, for those of you who showed up late to class, the question is whether
there is a mtb FD that can swing close enough to the seat tube to handle
an inner ring that close to the tube? Neither my Nexave nor my Acera can.
BTW, pm has suggested that "any old mtb derailleur in a bottom swing style
should work better."
Anyone?


Like this? (mind wrap, if necessary...)

http://cgi.ebay.com/Shimano-LX-front...d=p3286.c0.m14

E.P.

Cool. Thanks!

--
Mike "Rocket J Squirrel"