Bodge for di2 to get lower gear?

A friend coaches a quadreplegic handcyclist, who has trouble with
shifting. we're thinking a bite valve might be rigged to make di2
work. But the 50-34 by 27 max cog is too high. I've heard the front
and rear shifting is linked, but can anyone sugest a way to run di2
with two smaller chainrings? Right now she uses 28 (triple) by 28
lowest cog.

Other suggestions, such as cable shifting options welcome too.

mtb Dad wrote:

A friend coaches a quadreplegic handcyclist,

Now that would be a Zen coaching job.

Don't you mean paraplegic?

Chalo

On Jan 25, 2:56*pm, mtb Dad wrote:
A friend coaches a quadreplegic handcyclist, who has trouble with
shifting. *we're thinking a bite valve might be rigged to make di2
work. *But the 50-34 by 27 max cog is too high. *I've heard the front
and rear shifting is linked, but can anyone sugest a way to run di2
with two smaller chainrings? *Right now she uses 28 (triple) by 28
lowest cog.

Other suggestions, such as cable shifting options welcome too.

If the build is custom, there's always using a second "bottom bracket"
with a couple rings to step down the gearing, but that's not terribly
elegant. What's wrong with using conventional mtb hand controls other
than fugly lengths of jiggly housing?

On Jan 25, 9:15*pm, Chalo wrote:
mtb Dad wrote:

A friend coaches a quadreplegic handcyclist,

Now that would be a Zen coaching job.

Don't you mean paraplegic?

Chalo

No, arms are affected. I don't know the extent, but her hands and
shoulders are good enough to operate the pedals, but not so good for
shifting mechanisms.

"quadriplegia, is paralysis caused by illness or injury to a human
that results in the partial or total loss of use of all their limbs
and torso; Paraplegia is similar but does not affect the
arms." (wikipedia)

On Jan 25, 9:32*pm, landotter wrote:
On Jan 25, 2:56*pm, mtb Dad wrote:

A friend coaches a quadreplegic handcyclist, who has trouble with
shifting. *we're thinking a bite valve might be rigged to make di2
work. *But the 50-34 by 27 max cog is too high. *I've heard the front
and rear shifting is linked, but can anyone sugest a way to run di2
with two smaller chainrings? *Right now she uses 28 (triple) by 28
lowest cog.

Other suggestions, such as cable shifting options welcome too.

If the build is custom, there's always using a second "bottom bracket"
with a couple rings to step down the gearing, but that's not terribly
elegant. What's wrong with using conventional mtb hand controls other
than fugly lengths of jiggly housing?

Thanks. I will pass that along. I think it's the manipulation of
smaller levers that's the problem. And, IIRC, she has her hands
strapped to, or inserted in the pedals somehow, so moving them to
shift is slow. From watching her, I'd say regular grip shifts are out
too. Maybe a larger paddle-style handgrip/pedal, that she twists, like
a grip shift but with more leverage? But then her wrist would be
cocked in some gears, unless it was ratcheted.

Why not go with a triple, with regular mechanical shifting, coupled
with a di2 electronic rear?

Mount 27/38/48 rings on the triple with some form of cable shift - but
that will not be used very often. Use the 12/27 cassette and she'll
have the same low gear as she has now, and quick/easy electronic
shifts. Even the able bodied rarely shift at the front, it's 99% rear.

On Jan 25, 4:04*pm, mtb Dad wrote:
On Jan 25, 9:32*pm, landotter wrote:

On Jan 25, 2:56*pm, mtb Dad wrote:

A friend coaches a quadreplegic handcyclist, who has trouble with
shifting. *we're thinking a bite valve might be rigged to make di2
work. *But the 50-34 by 27 max cog is too high. *I've heard the front
and rear shifting is linked, but can anyone sugest a way to run di2
with two smaller chainrings? *Right now she uses 28 (triple) by 28
lowest cog.

Other suggestions, such as cable shifting options welcome too.

If the build is custom, there's always using a second "bottom bracket"
with a couple rings to step down the gearing, but that's not terribly
elegant. What's wrong with using conventional mtb hand controls other
than fugly lengths of jiggly housing?

Thanks. *I will pass that along. *I think it's the manipulation of
smaller levers that's the problem. *And, IIRC, she has her hands
strapped to, or inserted in the pedals somehow, so moving them to
shift is slow. From watching her, I'd say regular grip shifts are out
too. Maybe a larger paddle-style handgrip/pedal, that she twists, like
a grip shift but with more leverage? But then her wrist would be
cocked in some gears, unless it was ratcheted.

Cancel that. Can't see how you'd do a rachet shift mechanism on a
pedal. Maybe an elbow device on each side? One tap for up, two for
down? Hey, that sounds familiar....

On Jan 25, 6:04*pm, mtb Dad wrote:
On Jan 25, 9:32*pm, landotter wrote:

On Jan 25, 2:56*pm, mtb Dad wrote:

A friend coaches a quadreplegic handcyclist, who has trouble with
shifting. *we're thinking a bite valve might be rigged to make di2
work. *But the 50-34 by 27 max cog is too high. *I've heard the front
and rear shifting is linked, but can anyone sugest a way to run di2
with two smaller chainrings? *Right now she uses 28 (triple) by 28
lowest cog.

Other suggestions, such as cable shifting options welcome too.

If the build is custom, there's always using a second "bottom bracket"
with a couple rings to step down the gearing, but that's not terribly
elegant. What's wrong with using conventional mtb hand controls other
than fugly lengths of jiggly housing?

Thanks. *I will pass that along. *I think it's the manipulation of
smaller levers that's the problem. *And, IIRC, she has her hands
strapped to, or inserted in the pedals somehow, so moving them to
shift is slow. From watching her, I'd say regular grip shifts are out
too. Maybe a larger paddle-style handgrip/pedal, that she twists, like
a grip shift but with more leverage? But then her wrist would be
cocked in some gears, unless it was ratcheted.

How limited is her hand dexterity? That would be of huge interest to
us in the peanut gallery.

On Jan 25, 7:26*pm, landotter wrote:
On Jan 25, 6:04*pm, mtb Dad wrote:









On Jan 25, 9:32*pm, landotter wrote:

On Jan 25, 2:56*pm, mtb Dad wrote:

A friend coaches a quadreplegic handcyclist, who has trouble with
shifting. *we're thinking a bite valve might be rigged to make di2
work. *But the 50-34 by 27 max cog is too high. *I've heard the front
and rear shifting is linked, but can anyone sugest a way to run di2
with two smaller chainrings? *Right now she uses 28 (triple) by 28
lowest cog.

Other suggestions, such as cable shifting options welcome too.

If the build is custom, there's always using a second "bottom bracket"
with a couple rings to step down the gearing, but that's not terribly
elegant. What's wrong with using conventional mtb hand controls other
than fugly lengths of jiggly housing?

Thanks. *I will pass that along. *I think it's the manipulation of
smaller levers that's the problem. *And, IIRC, she has her hands
strapped to, or inserted in the pedals somehow, so moving them to
shift is slow. From watching her, I'd say regular grip shifts are out
too. Maybe a larger paddle-style handgrip/pedal, that she twists, like
a grip shift but with more leverage? But then her wrist would be
cocked in some gears, unless it was ratcheted.

How limited is her hand dexterity? That would be of huge interest to
us in the peanut gallery.

Ah, caught that other post. Limited would be the word. If she's able
to operate a brake lever, though--I'm gonna make the assumption that a
shifter shouldn't be too difficult--as the pressure involved is often
less? Or is it the complexity of moving a hand from a brake, to a
shifting position? The more details, the better. :-)

"mtb Dad" wrote in message
...
A friend coaches a quadreplegic handcyclist, who has trouble with
shifting. we're thinking a bite valve might be rigged to make di2
work. But the 50-34 by 27 max cog is too high. I've heard the front
and rear shifting is linked, but can anyone sugest a way to run di2
with two smaller chainrings? Right now she uses 28 (triple) by 28
lowest cog.

Other suggestions, such as cable shifting options welcome too.

Di2 ain't going to do the job on its own. I was trying to figure out if you
could switch the cage on the rear derailleur, but probably not a good idea
to mess with it. And the front... forget it. The reason it works at all (and
works so well) is that you've got known quantities for it to deal with, and
an outrageously-stiff chainring set.

But maybe there's a simpler, more obvious solution. What if you matched up
Di2 to an internally-geared hub? I'm trying to figure out why that wouldn't
work. Obviously you'd still have to work the (manual) controls for the hub,
but you might not have to do it too often.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA