Rotor System Question

On 11 May 2004 13:37:22 -0700, [email hidden] (n crowley)

Quoted message said:

Using two bikes with rear wheels of identical size and with
identical gearing, one bike fitted with rotor cranks and
the other with normal cranks, set the upper crank of both
bikes to that forward position of the upper rotor crank
when its lower crank is at 6 o'clock. Now measuring the
exact distance that each bike will travel as its upper
crank is moved from that forward position to the 3 o'clock
mark, how will the distances compare ?

Dear N.,

I think that both bikes will move the same distance if you
push one pedal through 3/4ths of a revolution from top
dead center.

That is, view a bicycle from its left side with 12 o'clock
as top dead center, 9 o'clock as level and toward the front
wheel, 6 o'clock as bottom dead center, and 3 o'clock as
level and toward the rear wheel.

I may be wrong, but I have a vague notion that the pedal
arms of a rotor crank turn somewhat independently, the idea
being to train the rider to pull his idle foot up on its own
instead of being pushed up at least partly by the downward
force of the active foot.

If so, forcing one pedal through 3/4ths of a revolution will
produce the same effect on both normal and rotor cranks.

I don't think that any gearing advantage or change is
claimed, just a pair of pedal arms that require each foot to
pull its own weight on the back half of the pedal circle.
Whether such training has any practical effect is regularly
debated here on rec.bicycles.tech.

I'm not sure how much independence the rotor cranks offer.
If they're completely independent, both could hang straight
down at the same time. If they offer only a few degrees of
independence, then one might be able to trail the other by
twenty degrees, or some similar figure.

Carl Fogel

[email hidden] wrote in
:"]news:[email hidden]:

Quoted message said:

On 11 May 2004 13:37:22 -0700, [email hidden] (n

crowley) said:

Using two bikes with rear wheels of identical size and
with identical gearing, one bike fitted with rotor cranks
and the other with normal cranks, set the upper crank of
both bikes to that forward position of the upper rotor
crank when its lower crank is at 6 o'clock. Now measuring
the exact distance that each bike will travel as its upper
crank is moved from that forward position to the 3 o'clock
mark, how will the distances compare ?

I don't think we really know how far it is from the upper
position to 3:00. Or how much leverage you gain with the
Rotor cranks. As a guess, I'd say the rotor crank would move
not quite as far. Because you're not moving the crank arm as
much. Probably it catches up by 6:00, though.

<snip stuff>

Quoted message said:

I may be wrong, but I have a vague notion that the pedal
arms of a rotor crank turn somewhat independently, the
idea being to train the rider to pull his idle foot up on
its own instead of being pushed up at least partly by the
downward force of the active foot.

If so, forcing one pedal through 3/4ths of a
revolution will produce the same effect on both normal
and rotor cranks.

I don't think that any gearing advantage or change is
claimed, just a pair of pedal arms that require each foot
to pull its own weight on the back half of the pedal
circle. Whether such training has any practical effect is
regularly debated here on rec.bicycles.tech.

I'm not sure how much independence the rotor cranks offer.
If they're completely independent, both could hang
straight down at the same time. If they offer only a few
degrees of independence, then one might be able to trail
the other by twenty degrees, or some similar figure.

Actually, that's PowerCranks: www.powercranks.com Both crank
arms are completely independent, and they can indeed both
hang straight down.

Rotorcranks move the foot up more quickly on the up-stroke,
so that when the lower foot is at 6:00, the other foot is at
1:30 or so. Claimed to increase leverage, lower threshold
heart rate, and make you go faster.
rotorcranksusa.comrotorcranksusa.comOpen ↗

Owen

Owen Pope said:

[email hidden] wrote in
:"]news:[email hidden]:

Quoted message said:

On 11 May 2004 13:37:22 -0700, [email hidden] (n

crowley) said:

Using two bikes with rear wheels of identical size and
with identical gearing, one bike fitted with rotor cranks
and the other with normal cranks, set the upper crank of
both bikes to that forward position of the upper rotor
crank when its lower crank is at 6 o'clock. Now measuring
the exact distance that each bike will travel as its
upper crank is moved from that forward position to the 3
o'clock mark, how will the distances compare ?

I don't think we really know how far it is from the upper
position to 3:00. Or how much leverage you gain with the
Rotor cranks. As a guess, I'd say the rotor crank would
move not quite as far. Because you're not moving the crank
arm as much. Probably it catches up by 6:00, though.

<snip stuff>

Quoted message said:

I may be wrong, but I have a vague notion that the pedal
arms of a rotor crank turn somewhat independently, the
idea being to train the rider to pull his idle foot up on
its own instead of being pushed up at least partly by the
downward force of the active foot.

If so, forcing one pedal through 3/4ths of a revolution
will produce the same effect on both normal and rotor
cranks.

I don't think that any gearing advantage or change is
claimed, just a pair of pedal arms that require each foot
to pull its own weight on the back half of the pedal
circle. Whether such training has any practical effect is
regularly debated here on rec.bicycles.tech.

I'm not sure how much independence the rotor cranks
offer. If they're completely independent, both could hang
straight down at the same time. If they offer only a few
degrees of independence, then one might be able to trail
the other by twenty degrees, or some similar figure.

Actually, that's PowerCranks: www.powercranks.com Both
crank arms are completely independent, and they can indeed
both hang straight down.

Rotorcranks move the foot up more quickly on the up-stroke,
so that when the lower foot is at 6:00, the other foot is
at 1:30 or so. Claimed to increase leverage, lower
threshold heart rate, and make you go faster.
rotorcranksusa.comrotorcranksusa.comOpen ↗

Owen

Dear Owen,

You're right and I'm wrong (as private email also
pointed out).

I confused RotorCranks and PowerCranks--d'oh!

Homer Simpson

[QUOTE]Originally posted by Owen Pope
[B][email hidden] wrote in
:"]news:[email hidden]:

Quoted message said:

On 11 May 2004 13:37:22 -0700, [email hidden] (n

crowley) said:

Using two bikes with rear wheels of identical size and
with identical gearing, one bike fitted with rotor cranks
and the other with normal cranks, set the upper crank of
both bikes to that forward position of the upper rotor
crank when its lower crank is at 6 o'clock. Now measuring
the exact distance that each bike will travel as its upper
crank is moved from that forward position to the 3 o'clock
mark, how will the distances compare ?

Quoted message said:

I may be wrong, but I have a vague notion that the pedal
arms of a rotor crank turn somewhat independently, the
idea being to train the rider to pull his idle foot up on
its own instead of being pushed up at least partly by the
downward force of the active foot.

If so, forcing one pedal through 3/4ths of a
revolution will produce the same effect on both normal
and rotor cranks.

I don't think that any gearing advantage or change is
claimed, just a pair of pedal arms that require each foot
to pull its own weight on the back half of the pedal
circle. Whether such training has any practical effect is
regularly debated here on rec.bicycles.tech.

I'm not sure how much independence the rotor cranks offer.
If they're completely independent, both could hang
straight down at the same time. If they offer only a few
degrees of independence, then one might be able to trail
the other by twenty degrees, or some similar figure.

n crowley said:

Actually, that's PowerCranks: www.powercranks.com Both
crank arms are completely independent, and they can indeed
both hang straight down.

You are correct about the Powercranks

Quoted message said:

Rotorcranks move the foot up more quickly on the up-
stroke, so that

But here you are misinformed. It is over TDC ( Top Dead
Center ) where the foot moves quicker. The downstroke and
upstroke are perfectly normal, where you for instance can
let your upstroke leg be lifted up by the downstroke leg.
When the upstroke gets close to TDC it is speeded through so
that you can begin mashing down sooner. I can't remember if
the pedal pointing down at this moment is then speeded
through BDC ( Bottom Dead Center ) I would imagine so.

Quoted message said:

when the lower foot is at 6:00, the other foot is at
1:30 or so. Claimed to increase leverage, lower threshold
heart rate,

Now you're caught up again 😉

Quoted message said:

and make you go faster.

I tried them out shortly at a bikeshow, but they evidently
hadn't expected anybody to put any power on them so the
crankarms started slipping and came out of position. They
had to stop the demo for the rest of that day. Evidently
they need some attention getting set up right. From what I
experienced they felt perfectly normal in the sense that I
could just start pedaling away as opposed to the Powercranks
that take some getting used to.

--
Perre

You have to be smarter than a robot to reply.

[QUOTE]Originally posted by Per ElmsäTer

Bn crowley said:

Actually, that's PowerCranks: www.powercranks.com Both
crank arms are completely independent, and they can indeed
both hang straight down.

Quoted message said:

Rotorcranks move the foot up more quickly on the up-
stroke, so that

Quoted message said:

when the lower foot is at 6:00, the other foot is at
1:30 or so. Claimed to increase leverage, lower threshold
heart rate,

Quoted message said:

and make you go faster.