Rotor Cranks

Mike said:

Would be interested if anyone has any experience with these ... real or fiction?

I installed a set ten days ago , against my intuition.

My customer said yesterday that he is sore in places he never knew there were muscles. He considers
that a positive experience - that's just what he expected. He reports that he works a lot harder
when the crank doesn't lift the back leg.

OK, I understand it, but they seem awfully expensive. Ugly. Heavy, too. But they do what they claim

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

On 23 Dec 2003 20:03:50 -0800, [email hidden] (Mike) may have

Quoted message said:

Would be interested if anyone has any experience with these ... real or fiction?

This was a relatively recent topic of debate.

A few people thought they had a valid purpose. Others were of the opinion that the alleged reason
for their existence (training the rider to use the dead-spot and upstroke portions of the crank
rotation to produce propulsive effort) was either not sufficiently important to merit the exercise
in retraining, or that the same technique could be learned without either the expense or the
frustration of the rotor cranks. Some maintained that it was utterly useless. I can't say that there
was a genuine consensus, but my impression was that the majority opinion was that they're either not
worth the expense or not worth the effort. Your mileage may vary. I'd recommend consulting Google
for the previous threads in order to get the full discussion.

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Werehatrack said:

(Mike) may have said:

Would be interested if anyone has any experience with these ... real or fiction?

This was a relatively recent topic of debate.

A few people thought they had a valid purpose. Others were of the opinion that the alleged reason
for their existence (training the rider to use the dead-spot and upstroke portions of the crank
rotation to produce propulsive effort) was either not sufficiently important to merit the exercise
in retraining, or that the same technique could be learned without either the expense or the
frustration of the rotor cranks. Some maintained that it was utterly useless. I can't say that
there was a genuine consensus, but my impression was that the majority opinion was that they're
either not worth the expense or not worth the effort. Your mileage may vary. I'd recommend
consulting Google for the previous threads in order to get the full discussion.

I believe that you have confused "Power Cranks" [1] with "Rotor Cranks"
[2]. The two systems operate very differently.

[3] < powercranks.compowercranks.comOpen ↗>.
[4] < rotorbike.comrotorbike.comOpen ↗>.

Tom Sherman - 41 N, 90 W

A Muzi <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Mike said:

Would be interested if anyone has any experience with these ... real or fiction?

I installed a set ten days ago , against my intuition.

My customer said yesterday that he is sore in places he never knew there were muscles. He
considers that a positive experience - that's just what he expected. He reports that he works a
lot harder when the crank doesn't lift the back leg.

OK, I understand it, but they seem awfully expensive. Ugly. Heavy, too. But they do what
they claim

It sounds as though you are describing PowerCranks, a training system that forces the rider to
lift the pedal on the upstroke and where the two cranks are completely independent. Rotor Cranks
are a system that speeds each crank as it goes over top of the stroke and is claimed to provide
extra power.

--
Dave...

Quoted post said:

Originally posted by Mike
Would be interested if anyone has any experience with these ... real or fiction?

here is a review from roadbike rider.com

http://www.roadbikerider.com/pr8.htm#Rotor%20Crank%20System

personally the price and weight would put me off

"Mike" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Would be interested if anyone has any experience with these ... real or

fiction?

The true problem with all devices of this generic type - multiple-link cranks, non-circular rings,
arm-and-leg cranks, etcetera - is that over the distances usually traversed, the limit to human
power production in a reasonably fit individual is not the volume of muscle doing the work, when it
is at least that of the legs in normal cycling.

There remain the smaller disadvantages of increased weight, friction, complexity (read:
reliability) and cost.

The only possible advantage is that of placebo.

michael<< Would be interested if anyone has any experience with these ... real or fiction?

Quoted message said:

Quoted message said:

<BR><BR>

We have a pair on a test ride bike and altho they feel a little wierd at first, ya get used to them
fairly quickly. I think they would help big gear mashers, like some triatletes, but little to no
help for a person that has a smooth pedal stroke.

Where are you? If around the 'republic', come and ride the Serotta with them.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali costruite eccezionalmente bene"

On Wed, 24 Dec 2003 04:06:41 -0600, Tom Sherman

may have said:

I believe that you have confused "Power Cranks" [1] with "Rotor Cranks"
[2]. The two systems operate very differently.

[1] < powercranks.compowercranks.comOpen ↗>.
[2] < rotorbike.comrotorbike.comOpen ↗>.

Yes, I was confusing them. On the other hand, for myself, there's enough similarity between them in
important respects (the difficulty of synchronizing pedal positions, the even greater difficulty of
using them while not seated, the lack of availability of the upstroke-side pedal as a weight support
platform when encountering bumps, etc) that they share a lot of the same objections. There might be
places in human-powered devices where these ideas would be useful, but I question their validity for
bikes. Since the crank of a bike serves more purposes than just propulsion in fact, and those
purposes can be critically needed at times, I find the relegation of the crank to being reliably
useful solely for propulsion to be a disadvantage that rules out their use by me in everyday riding.

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Quoted message said:

Quoted message said:

On 23 Dec 2003 20:03:50 -0800, [email hidden]

(Mike) may have

Quoted message said:

Quoted message said:

Quoted message said:

Would be interested if anyone has any experience with these ... real or fiction?

Quoted message said:

Werehatrack said:

This was a relatively recent topic of debate.

-snip-

Tom Sherman said:

I believe that you have confused "Power Cranks" [1] with "Rotor Cranks"
[2]. The two systems operate very differently.

[1] < powercranks.compowercranks.comOpen ↗>.
[2] < rotorbike.comrotorbike.comOpen ↗>.

Guilty as charged. Thanks, Tom. I installed the system which allows each crank to rotate separately;
Power Cranks IIRC.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Quoted message said:

Quoted message said:

Mike said:

Would be interested if anyone has any experience with these ... real or fiction?

Quoted message said:

A Muzi <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I installed a set ten days ago , against my intuition.

My customer said yesterday that he is sore in places he never knew there were muscles. He
considers that a positive experience - that's just what he expected. He reports that he works a
lot harder when the crank doesn't lift the back leg.

OK, I understand it, but they seem awfully expensive. Ugly. Heavy, too. But they do what
they claim

Dave Kahn said:

It sounds as though you are describing PowerCranks, a training system that forces the rider to
lift the pedal on the upstroke and where the two cranks are completely independent. Rotor Cranks
are a system that speeds each crank as it goes over top of the stroke and is claimed to provide
extra power.

Yes I confused the two names, thank you .

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Werehatrack said:

Tom Sherman may have said:

I believe that you have confused "Power Cranks" [1] with "Rotor Cranks"
[2]. The two systems operate very differently.

[1] < powercranks.compowercranks.comOpen ↗>.
[2] < rotorbike.comrotorbike.comOpen ↗>.

Yes, I was confusing them. On the other hand, for myself, there's enough similarity between them
in important respects (the difficulty of synchronizing pedal positions, the even greater
difficulty of using them while not seated, the lack of availability of the upstroke-side pedal as
a weight support platform when encountering bumps, etc) that they share a lot of the same
objections. There might be places in human-powered devices where these ideas would be useful, but
I question their validity for bikes. Since the crank of a bike serves more purposes than just
propulsion in fact, and those purposes can be critically needed at times, I find the relegation of
the crank to being reliably useful solely for propulsion to be a disadvantage that rules out their
use by me in everyday riding.

--
My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I
don't respond to something, it's also possible that I'm busy. Words processed in a facility that
contains nuts.

It sounds like you're still confusing them. The Rotor cranks don't require any action by the rider
to synchronize cranks; while they are not at 180 degrees from each other at all points in the cycle,
their phase is determined by the mechanism at all points in the cycle, not by the rider.

There is no reason you can't stand on the pedals with them horizontal (or in any other position).
When they are horizontal, they will be near the standard 180 degrees from each other. There is also
no reason you can't stand while pedalling, although they will doubtless feel different.

I'm not saying Rotor's claims of increased performance are valid, or that they don't have penalties
in weight, cost, and added complexity. But your specific objections apply to the Power Cranks, not
to the Rotor cranks.

Dave Lehnen

On Wed, 24 Dec 2003 22:22:30 GMT, Dave Lehnen

may have said:

The Rotor cranks don't require any action by the rider to synchronize cranks; while they are not at
180 degrees from each other at all points in the cycle, their phase is determined by the mechanism
at all points in the cycle, not by the rider.

Reviewing the information again, I see that the rotor cranks have fewer serious drawbacks than the
powercrank setup, but it's still a nonzero disadvantage set.

In particular, if the effective lever arm at all points is not equal, it's going to make the
apparent balance point seem wrong, is it not? To *keep* the crank horizontal, the weight
distribution would have to favor the forward foot, no? In a descent over uneven terrain, this is not
a welcome effect.

Quoted message said:

There is no reason you can't stand on the pedals with them horizontal (or in any other position).
When they are horizontal, they will be near the standard 180 degrees from each other. There is also
no reason you can't stand while pedalling, although they will doubtless feel different.

I do a lot of things by feel; I suspect that it would be hard to get used to having this variation
present, particularly when unwanted riding conditions have already made life complicated in an
unexpected manner.

Quoted message said:

I'm not saying Rotor's claims of increased performance are valid, or that they don't have penalties
in weight, cost, and added complexity. But your specific objections apply to the Power Cranks, not
to the Rotor cranks.

The weight factor is probably more important to a lot of other people than it is to me, but it's a
factor none the less. The expense is a larger consideration; a nonessential device that costs this
much would be unlikely to be of the least bit of interest to me, since I am a decidely casual rider
in most instances.

All things considered, I will continue to not spend my money on this gadget.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.

Quoted post said:

Originally posted by eric_the_red
here is a review from roadbike rider.com

http://www.roadbikerider.com/pr8.htm#Rotor%20Crank%20System

personally the price and weight would put me off

Here's a good summary of the difference between PowerCranks and RotorCranks.
http://www.fact-canada.com/wwwboard/messages/79.html
That dealer sells both.

BTW: here’s another unusual crank- arm length lengthens on the forward side, shortens on the back side. Max torque with level cranks, min torque with crank arms vertical. This is approximately 90 degrees out of phase with RotorCranks and Biopace. The pedals turn in a circular direction still.

www.easycrank.com

Werehatrack said:

Dave Lehnen may have said:

The Rotor cranks don't require any action by the rider to synchronize cranks; while they are not
at 180 degrees from each other at all points in the cycle, their phase is determined by the
mechanism at all points in the cycle, not by the rider.

Reviewing the information again, I see that the rotor cranks have fewer serious drawbacks than the
powercrank setup, but it's still a nonzero disadvantage set.

In particular, if the effective lever arm at all points is not equal, it's going to make the
apparent balance point seem wrong, is it not? To *keep* the crank horizontal, the weight
distribution would have to favor the forward foot, no? In a descent over uneven terrain, this is
not a welcome effect.

Quoted message said:

There is no reason you can't stand on the pedals with them horizontal (or in any other position).
When they are horizontal, they will be near the standard 180 degrees from each other. There is
also no reason you can't stand while pedalling, although they will doubtless feel different.

I do a lot of things by feel; I suspect that it would be hard to get used to having this variation
present, particularly when unwanted riding conditions have already made life complicated in an
unexpected manner.

Quoted message said:

I'm not saying Rotor's claims of increased performance are valid, or that they don't have
penalties in weight, cost, and added complexity. But your specific objections apply to the Power
Cranks, not to the Rotor cranks.

The weight factor is probably more important to a lot of other people than it is to me, but it's a
factor none the less. The expense is a larger consideration; a nonessential device that costs this
much would be unlikely to be of the least bit of interest to me, since I am a decidely casual
rider in most instances.

All things considered, I will continue to not spend my money on this gadget.

I think you are missing the point of the "PowerCranks", unlike the "Rotor Cranks" they do not make a
claim of increased performance, but are intended to train the rider so that he/she will have better
performance while using standard cranks. Therefore, the "disadvantages" of the "PowerCranks" should
not be seen as any more of a disadvantage than carrying ballast for training purposes - they are not
intended to offer performance superior to regular cranks.

Whether or not training with PowerCranks is effective as claimed (or at all) is another matter.

The MSRP of $690 US for the basic version is rather pricey.

Tom Sherman - 41½ N, 90½ W

On Wed, 24 Dec 2003 18:51:57 -0600, Tom Sherman

may have said:

I think you are missing the point of the "PowerCranks", unlike the "Rotor Cranks" they do not make
a claim of increased performance, but are intended to train the rider so that he/she will have
better performance while using standard cranks.

As I pointed out in the previous discussion of that topic, their "training method" is severe and
unnecessary. If I wanted to achieve what they claim to facilitate, I could do so myself. In point of
fact, back in the early '70s, the pedaling technique "trained" by the Powercranks was something I
had already schooled myself to use...and then twenty years of disuse erased the habit. If I wanted
to re-acquire it, though, I could do so without spending such an exorbitant amount on a gimmick that
rendered the bike objectionable to the point of infuriating to ride. Machinery that does not behave
in a civilized manner is fodder for recycling, not purchase, in my opinion.

Quoted message said:

Therefore, the "disadvantages" of the "PowerCranks" should not be seen as any more of a
disadvantage than carrying ballast for training purposes - they are not intended to offer
performance superior to regular cranks.

Whether or not training with PowerCranks is effective as claimed (or at all) is another matter.

The MSRP of $690 US for the basic version is rather pricey.

Tom Sherman - 41½ N, 90½ W

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.

"Werehatrack" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Tom Sherman may have said:

I believe that you have confused "Power Cranks" [1] with "Rotor Cranks"
[2]. The two systems operate very differently.

[1] < powercranks.compowercranks.comOpen ↗>.
[2] < rotorbike.comrotorbike.comOpen ↗>.

Yes, I was confusing them. On the other hand, for myself, there's enough similarity between them
in important respects (the difficulty of synchronizing pedal positions, the even greater
difficulty of using them while not seated, the lack of availability of the upstroke-side pedal as
a weight support platform when encountering bumps, etc)

Rotorcranks have none of the limitations you mention.

Andy Coggan

Andy Coggan said:

Rotorcranks have none of the limitations you mention.

When are you going to report back to us on your experiences?

meb <[email hidden]> wrote in message news>

Quoted message said:

Here's a good summary of the difference between PowerCranks and RotorCranks. fact-fact-Open ↗
canada.com/wwwboard/messages/79.html That dealer sells both.

BTW: here?s another unusual crank- arm length lengthens on the forward side, shortens on the back
side. Max torque with level cranks, min torque with crank arms vertical. This is approximately 90
degrees out of phase with RotorCranks and Biopace. The pedals turn in a circular direction still.

www.easycrank.com

We may need a summary of the difference between Biopace and Rotor. While the full Rotor effect can't
be got with a funny chainring (although it could be done with two), the mechanical advantage of
Rotor varies in a way that is more like a traditional elliptical than Biopace. (Biopace and
traditional are about as out of phase as you can get ie ~90 deg).

Easycrank looks very much like the "Sun-wheel" variable crank length machine reported here a year or
so back. This machine got into "Nature" nature.com020923 12.htmlOpen ↗.

The idea was supposed to be the reduction of "reverse torque" on the upstroke - which, if it could
be maintained, would seem to have the bike going down the road under the weight of it's own pedals
and would provide a very clean solution to the worlds energy needs.

Testing is of course the acid test and the system comes with a favorable peer-reviewed report in the
Journal of Biomechanics.

In a few years it's a fair bet we will see a combination of Easycrank and Rotor.

Andrew Bradley

[email hidden] (Andrew Bradley) wrote in message news:<[email hidden]>...

Quoted message said:

meb <[email hidden]> wrote in message news>

Quoted message said:

Here's a good summary of the difference between PowerCranks and RotorCranks. fact-fact-Open ↗
canada.com/wwwboard/messages/79.html That dealer sells both.

BTW: here?s another unusual crank- arm length lengthens on the forward side, shortens on the
back side. Max torque with level cranks, min torque with crank arms vertical. This is
approximately 90 degrees out of phase with RotorCranks and Biopace. The pedals turn in a
circular direction still.

www.easycrank.com

We may need a summary of the difference between Biopace and Rotor. While the full Rotor effect
can't be got with a funny chainring (although it could be done with two), the mechanical advantage
of Rotor varies in a way that is more like a traditional elliptical than Biopace. (Biopace and
traditional are about as out of phase as you can get ie ~90 deg).

Easycrank looks very much like the "Sun-wheel" variable crank length machine reported here a year
or so back. This machine got into "Nature" nature.com020923 12.htmlOpen ↗.

The idea was supposed to be the reduction of "reverse torque" on the upstroke - which, if it could
be maintained, would seem to have the bike going down the road under the weight of it's own pedals
and would provide a very clean solution to the worlds energy needs.

Testing is of course the acid test and the system comes with a favorable peer-reviewed report in
the Journal of Biomechanics.

In a few years it's a fair bet we will see a combination of Easycrank and Rotor.

Andrew Bradley

Dear Andrew,

And what--hic!--if you lashed a combination of Easycrank and Rotor to a Biopace chainring at
45 degrees?

Sorry--that's the egg-nog talking.

Wait a second--I don't drink!

Bartender, another round for these fine fellows and top up this Coca-cola for me!

Carl Fogel