Deore XT rear derailleur (9sp?) on Ultegra 10sp system?

Could I use a new Shimano Deore XT "SGS" type rear derailleur (M760-
SGS, M761-SGS, M770-SGS, or M771-SGS), as the rear derailleur on an
all Ultegra 6600-series 10 speed drive train (incl. shifters)?

I'm trying to replace my old Ultegra drivetrain with new Ultegra
equipment that will give me a triple with hopefully a extra wide range
of gearing (e.g., 56-43-32 x 11-27). I've read the Ultegra 6603 front
derailleur might be nudged 2t beyond its capacity spec to handle that
crank chainring range, but Ultegra 6600-series rear derailleur spec is
only 37t capacity vs. the 40t+ that I need (52-32 + 27-11). So, ...

Would a Deore XT SGS RD (45t capacity) be a good match for an
otherwise Ultegra 10 speed system (6600-series triple STI, crank, FD,
cassette, chain, & bb; but using larger chainrings from, for example,
Specialites TA)? I understand that the Deore XT quality is similar to
Ultegra, though intended for 9sp mountain bikes.

In particular, is the XT RD able to handle a 10 speed cassette, or
would I have to downgrade the cassette to a 9 (old Ultegra or new XT)
or maybe I'd have to set the RD limit to stop before the largest
(10th) cog? ?

(If not, I may not be able to get the wide range of gearing I hoped
for.)

Thanks,

Craig in NJ

On Nov 16, 4:26*pm, CraiginNJ wrote:
Could I use a new Shimano Deore XT "SGS" type rear derailleur (M760-
SGS, M761-SGS, M770-SGS, or M771-SGS), *as the rear derailleur on an
all Ultegra 6600-series 10 speed drive train (incl. shifters)?

I'm trying to replace my old Ultegra drivetrain with new Ultegra
equipment that will give me a triple with hopefully a extra wide range
of gearing (e.g., 56-43-32 x 11-27). I've read the Ultegra 6603 front
derailleur might be nudged 2t beyond its capacity spec to handle that
crank chainring range, but Ultegra 6600-series rear derailleur spec is
only 37t capacity vs. the 40t+ that I need (52-32 + 27-11). So, ...

Would a Deore XT SGS RD (45t capacity) be a good match for an
otherwise Ultegra 10 speed system (6600-series triple STI, crank, FD,
cassette, chain, & bb; but using larger chainrings from, for example,
Specialites TA)? *I understand that the Deore XT quality is similar to
Ultegra, though intended for 9sp mountain bikes.

In particular, is the XT RD able to handle a 10 speed cassette, or
would I have to downgrade the cassette to a 9 (old Ultegra or new XT)
or maybe I'd have to set the RD limit to stop before the largest
(10th) cog? ?

(If not, I may not be able to get the wide range of gearing I hoped
for.)

Thanks,

Craig in NJ

Should work fine. Go for it!

On Nov 16, 6:28*pm, Hank wrote:
On Nov 16, 4:26*pm, CraiginNJ wrote:



Could I use a new Shimano Deore XT "SGS" type rear derailleur (M760-
SGS, M761-SGS, M770-SGS, or M771-SGS), *as the rear derailleur on an
all Ultegra 6600-series 10 speed drive train (incl. shifters)?

I'm trying to replace my old Ultegra drivetrain with new Ultegra
equipment that will give me a triple with hopefully a extra wide range
of gearing (e.g., 56-43-32 x 11-27). I've read the Ultegra 6603 front
derailleur might be nudged 2t beyond its capacity spec to handle that
crank chainring range, but Ultegra 6600-series rear derailleur spec is
only 37t capacity vs. the 40t+ that I need (52-32 + 27-11). So, ...

Would a Deore XT SGS RD (45t capacity) be a good match for an
otherwise Ultegra 10 speed system (6600-series triple STI, crank, FD,
cassette, chain, & bb; but using larger chainrings from, for example,
Specialites TA)? *I understand that the Deore XT quality is similar to
Ultegra, though intended for 9sp mountain bikes.

In particular, is the XT RD able to handle a 10 speed cassette, or
would I have to downgrade the cassette to a 9 (old Ultegra or new XT)
or maybe I'd have to set the RD limit to stop before the largest
(10th) cog? ?

(If not, I may not be able to get the wide range of gearing I hoped
for.)

Thanks,

Craig in NJ

Should work fine. Go for it!

I should add that the FD would be cause for greater concern than the
RD. Why the big gears? Recumbent or folder?

On Nov 16, 9:31*pm, Hank wrote:
Should work fine. Go for it!
I should add that the FD would be cause for greater concern
than the RD. Why the big gears?

Thanks for the thumbs up. Are you saying the XT RD should have no
trouble with the 10 Ultegra cassette cogs and STI's? (I imagined the
XT might be callibrated for slightly different spacing of a 9sp
mountain bike or might be unable to reach a 10th gear.)

FD concern: FD has 22t capacity, and I have read a good source
claim it can be pushed an extra 2t without much worry. In fact, I saw
one post from someone who had a 27t range (57-42-30) on his 22t-rated
Shimano road FD. Those references are why I don't think I need to
worry about the FD for the range I want.

Why the big range of gears? The usual reasons. With my old double, I
struggle with some steep climbs yet also spin-out on long slightly-
downsloped stretches. (Don't tell me to spin faster -- that just
isn't going to happen.)

Does anyone else agree that the XT RD should be a a good substitute
for an Ultegra?

Craig

On Nov 16, 9:29*pm, CraiginNJ wrote:
On Nov 16, 9:31*pm, Hank wrote:

Should work fine. Go for it!
I should add that the FD would be cause for greater concern
than the RD. Why the big gears?

Thanks for the thumbs up. *Are you saying the XT RD should have no
trouble with the 10 Ultegra cassette cogs and STI's? *(I imagined the
XT might be callibrated for slightly different spacing of a 9sp
mountain bike or might be unable to reach a 10th gear.)

Cable pull rate is identical for all Shimano SIS RDs except 6/7/8
speed Dura-Ace.


FD concern: FD has 22t capacity, and I have read a good source
claim it can be pushed an extra 2t without much worry. *In fact, I saw
one post from someone who had a 27t range (57-42-30) on his 22t-rated
Shimano road FD. *Those references are why I don't think I need to
worry about the FD for the range I want.

My concern is for the curvature of the cage...You can exceed the 22t
capacity by swapping the 30T ring for a 28. But by going with a 56T
ring, you'll not only need to raise it by the increase in
circumference, but you'll need to raise it to clear the tail end of
cage from the big ring. So if anything, the size of that big ring will
reduce the capacity of the FD down to 20 or 18T. And to hit the middle
ramp correctly, you'd probably need something like a 48T middle ring,
or it won't be able to shift onto the granny ring. And was the poster
you cite using STI or bar-ends? Most who use a ring that big are using
it on a Time Trial bike with bar-end shifters, which can be
overshifted then trimmed, while STIs can't. STIs have to follow mfr.
guidelines MUCH more closely, especially with a triple. A double FD is
about the simplest bike component to set up out there, but an indexed
triple is about the most complicated, and messing with the specs is
bad mojo.


Why the big range of gears? *The usual reasons. *With my old double, I
struggle with some steep climbs yet also spin-out on long slightly-
downsloped stretches. *(Don't tell me to spin faster -- that just
isn't going to happen.)

A 133 inch gear is over 35mph at 90rpm. At that speed on, say, a 10%
grade, the aerodynamic gains of keeping the crankarms parallel to the
ground and coasting will almost certainly outweigh anything you can
gain by pedaling a big gear. You'll feel like you're contributing, but
you're just expending energy that you don't have to.

If you really need a gear that big, you'd be better off getting a
Capreo rear hub and cassette, which is designed for small-wheel bikes.
A typical Capreo cassette is 9-26. With that, plus the standard
Ultegra 6603 52-39-30 chainrings, you'd get a lower low and a high of
over 150 inches. You'd also need a JTek Shiftmate since Capreo is only
available in 9-speed. Honestly, that would be a far more sensible
option.

Capreo Wheel + cassette + Shiftmate will almost certainly be cheaper
than 3 TA rings in oddball sizes.

Here's some info on Capreo:
http://sheldonbrown.com/capreo/index.html

Thank you for that most-excellent post, Hank.

"Cable pull rate" -- that's a very clear explanation that gives me
confidence not to worry about that concern.

curvature -- good discussion of the issues. I'm prepared to make
creative adjustments so the tail end of the cage clears the big ring.
Since 56 and 57 aren't unheard of, it doesn't seem an insurmountable
issue.

rpm & coasting -- guestimates are nice to play with, but on the
real-life sections of road I want the higher gear for, my speed drops
off fast if I don't keep pedaling. I can't sustain anything like
90rpm, nor do I want to. It's easier to change the bike to suit my
body than vice versa. (FYI - When I can coast, I do; powering down a
hill feels way too risky for me to push it for more than a few
seconds.)

Capreo -- I really love that suggestion. I had no idea a 9t cog
was possible. Yes, it sure seems effective, cheaper, less risky, and
lighter than a nonstandard chainrings on the crank. I wonder if
there's an inherent efficiency loss from having such a tiny 9t
circle. (It intuitively seems more efficient to have the leverage of
pulling on a circumference that is farther from the center of a ring,
though I don't know if that really matters to the physics of a bike's
chain & gears.)

Thanks, Hank! Very insightful. Excellent post. Much appreciated.

Craig in NJ

On Nov 17, 2:29*am, Hank wrote:
On Nov 16, 9:29*pm, CraiginNJ wrote:

On Nov 16, 9:31*pm, Hank wrote:

Should work fine. Go for it!
I should add that the FD would be cause for greater concern
than the RD. Why the big gears?

Thanks for the thumbs up. *Are you saying the XT RD should have no
trouble with the 10 Ultegra cassette cogs and STI's? *(I imagined the
XT might be callibrated for slightly different spacing of a 9sp
mountain bike or might be unable to reach a 10th gear.)

Cable pull rate is identical for all Shimano SIS RDs except 6/7/8
speed Dura-Ace.

FD concern: FD has 22t capacity, and I have read a good source
claim it can be pushed an extra 2t without much worry. *In fact, I saw
one post from someone who had a 27t range (57-42-30) on his 22t-rated
Shimano road FD. *Those references are why I don't think I need to
worry about the FD for the range I want.

My concern is for the curvature of the cage...You can exceed the 22t
capacity by swapping the 30T ring for a 28. But by going with a 56T
ring, you'll not only need to raise it by the increase in
circumference, but you'll need to raise it to clear the tail end of
cage from the big ring. So if anything, the size of that big ring will
reduce the capacity of the FD down to 20 or 18T. And to hit the middle
ramp correctly, you'd probably need something like a 48T middle ring,
or it won't be able to shift onto the granny ring. *And was the poster
you cite using STI or bar-ends? Most who use a ring that big are using
it on a Time Trial bike with bar-end shifters, which can be
overshifted then trimmed, while STIs can't. STIs have to follow mfr.
guidelines MUCH more closely, especially with a triple. A double FD is
about the simplest bike component to set up out there, but an indexed
triple is about the most complicated, and messing with the specs is
bad mojo.

Why the big range of gears? *The usual reasons. *With my old double, I
struggle with some steep climbs yet also spin-out on long slightly-
downsloped stretches. *(Don't tell me to spin faster -- that just
isn't going to happen.)

A 133 inch gear is over 35mph at 90rpm. At that speed on, say, a 10%
grade, the aerodynamic gains of keeping the crankarms parallel to the
ground and coasting will almost certainly outweigh anything you can
gain by pedaling a big gear. You'll feel like you're contributing, but
you're just expending energy that you don't have to.

If you really need a gear that big, you'd be better off getting a
Capreo rear hub and cassette, which is designed for small-wheel bikes.
A typical Capreo cassette is 9-26. With that, plus the standard
Ultegra 6603 52-39-30 chainrings, you'd get a lower low and a high of
over 150 inches. You'd also need a JTek Shiftmate since Capreo is only
available in 9-speed. Honestly, that would be a far more sensible
option.

Capreo Wheel + cassette + Shiftmate will almost certainly be cheaper
than 3 TA rings in oddball sizes.

Here's some info on Capreo:http://sheldonbrown.com/capreo/index.html

On Nov 17, 6:01*am, CraiginNJ wrote:
Thank you for that most-excellent post, Hank.

"Cable pull rate" -- that's a very clear explanation that gives me
confidence not to worry about that concern.

curvature -- *good discussion of the issues. *I'm prepared to make
creative adjustments so the tail end of the cage clears the big ring.
Since 56 and 57 aren't unheard of, it doesn't seem an insurmountable
issue.

56 and 57 aren't unheard of on double cranks on TT machines. The
FD-6600 Double FD specs a max. ring of 56. But the 6603 specs a 52
max. Those big rings just aren't supposed to go on triples.


rpm & coasting -- guestimates are nice to play with, but on the
real-life sections of road I want the higher gear for, my speed drops
off fast if I don't keep pedaling. *I can't sustain anything like
90rpm, nor do I want to. *It's easier to change the bike to suit my
body than vice versa. *(FYI - When I can coast, I do; powering down a
hill feels way too risky for me to push it for more than a few
seconds.)

Capreo -- I really love that suggestion. I had no idea a 9t cog
was possible. *Yes, it sure seems effective, cheaper, less risky, and
lighter than a nonstandard chainrings on the crank. *I wonder if
there's an inherent efficiency loss from having such a tiny 9t
circle. *(It intuitively seems more efficient to have the leverage of
pulling on a circumference that is farther from the center of a ring,
though I don't know if that really matters to the physics of a bike's
chain & gears.)

Larger ring & cog is ideal in most situations. Small/small will wear
quicker. In your case though, it seems to be the least undesirable
option.


Thanks, Hank! *Very insightful. *Excellent post. *Much appreciated.

Craig in NJ

No problem.

One other thing you might look at is the Schlumpf Speed Drive crank,
which has a 1.65 overdrive built-in.
http://www.schlumpf.ch/sd_engl.htm

Hank Wirtz wrote:
On Nov 17, 6:01 am, CraiginNJ wrote:
Thank you for that most-excellent post, Hank.

"Cable pull rate" -- that's a very clear explanation that gives me
confidence not to worry about that concern.

curvature -- good discussion of the issues. I'm prepared to make
creative adjustments so the tail end of the cage clears the big ring.
Since 56 and 57 aren't unheard of, it doesn't seem an insurmountable
issue.

56 and 57 aren't unheard of on double cranks on TT machines. The
FD-6600 Double FD specs a max. ring of 56. But the 6603 specs a 52
max. Those big rings just aren't supposed to go on triples.[...]

I run a 62/52/39 triple without problem, though the height adjustment of
the front derailer is critical. I could run a wider range if I trimmed
the cage with a grinder. It should be noted that this is shifter with a
SRAM twist-grip that has intermediate detents for trimming.

--
Tom Sherman - 42.435731,-83.985007
If you are not a part of the solution, you are a part of the precipitate.

Craig in NJ wrote:
[...]
Capreo -- I really love that suggestion. I had no idea a 9t cog
was possible. Yes, it sure seems effective, cheaper, less risky, and
lighter than a nonstandard chainrings on the crank. I wonder if
there's an inherent efficiency loss from having such a tiny 9t
circle. (It intuitively seems more efficient to have the leverage of
pulling on a circumference that is farther from the center of a ring,
though I don't know if that really matters to the physics of a bike's
chain & gears.)[...]

The greater loss (for a given chain tension) with a smaller tooth count
is primarily from bending the links at a greater angle as the wrap
around the sprocket.

--
Tom Sherman - 42.435731,-83.985007
If you are not a part of the solution, you are a part of the precipitate.

On Nov 17, 7:45*pm, Tom Sherman
wrote:
Hank Wirtz wrote:
On Nov 17, 6:01 am, CraiginNJ wrote:
Thank you for that most-excellent post, Hank.

"Cable pull rate" -- that's a very clear explanation that gives me
confidence not to worry about that concern.

curvature -- *good discussion of the issues. *I'm prepared to make
creative adjustments so the tail end of the cage clears the big ring.
Since 56 and 57 aren't unheard of, it doesn't seem an insurmountable
issue.

56 and 57 aren't unheard of on double cranks on TT machines. The
FD-6600 Double FD specs a max. ring of 56. But the 6603 specs a 52
max. Those big rings just aren't supposed to go on triples.[...]

I run a 62/52/39 triple without problem, though the height adjustment of
the front derailer is critical. I could run a wider range if I trimmed
the cage with a grinder. It should be noted that this is shifter with a
SRAM twist-grip that has intermediate detents for trimming.

--
Tom Sherman - 42.435731,-83.985007
If you are not a part of the solution, you are a part of the precipitate.


Is that a 6603 FD?

And I think that the 10t gap between big and middle is the key part
here - Craig was talking about a 13t gap at a higher mount than spec,
and like I mentioned, you can only get away with it if you're not
indexing.