Tech development or marketing ploy, redux

[Doug Taylor]

Okay, pundits, what's the verdict?

http://www.cyclingnews.com/tech/?id=2002/reviews/rotor_cranks

--dt

 

[Andy Coggan]

You decide:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_ui
ds=12165689&dopt=Abstract

(Note that the Rotor cranks do exactly what Jim set out to accomplish with this one-legged offset
chainring pedaling model, which is to alter the duty cycle from the normal 50%. While this was a
complete independent effort on Jim's part, I'll bet that if he'd been aware of Rotor cranks when
designing his study, he might have simply chosen to use them instead).

Andy Coggan

"Doug Taylor" <[email protected]> wrote in message
news:[email protected]...
> Okay, pundits, what's the verdict?
>
> http://www.cyclingnews.com/tech/?id=2002/reviews/rotor_cranks
>
>
> --dt

 

[Phil Holman]

"Andy Coggan" <[email protected]> wrote in message
news:[email protected]...
> You decide:
>
>
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=Pub Med&list_ui
> ds=12165689&dopt=Abstract
>
> (Note that the Rotor cranks do exactly what Jim set out to
accomplish with
> this one-legged offset chainring pedaling model, which is to
alter the duty
> cycle from the normal 50%. While this was a complete
independent effort on
> Jim's part, I'll bet that if he'd been aware of Rotor cranks
when designing
> his study, he might have simply chosen to use them instead).
>
> Andy Coggan
>
> "Doug Taylor" <[email protected]> wrote in message
> news:[email protected]...
> > Okay, pundits, what's the verdict?
> >
> > http://www.cyclingnews.com/tech/?id=2002/reviews/rotor_cranks

See also http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=Pub
Med&list_uids=12231284&dopt=Abstract

Article number 12231284 in pub med

Interesting studies. Jobst's ploy of associating these devices with cranks (crackpot variety) is a
weak argument of the fallacy of faulty analogy variety I.e. this is not about getting something for
nothing and the laws of thermodynamics are not being violated.

Phil Holman

 

[Ryan Cousineau]

In article <%[email protected]>, [email protected] wrote:

> Doug Taylor writes:
>
> > Okay, pundits, what's the verdict?
>
> http://www.cyclingnews.com/tech/?id=2002/reviews/rotor_cranks
>
> To bad these products never show a velocity profile for these solutions to non existent problems.
> If they did, you could see that this is nothing more than a complex way of converting the output
> of a round chainwheel to that of an elliptical one, using additional levers, bearings, and links.
>
> The claim of inefficiency with conventional cranks assumes that all development of piston engines,
> be they steam, diesel or gasoline powered, was amiss and that the correct solution for converting
> linear motion to circular motion will be found on bicycles. Investigating the definition of
> efficiency makes the concept fall apart because inefficiency means that energy is lost to heat
> somewhere in the power cycle. This is not so. Motion over the top and bottom of crank revolution
> requires no work and therefore, no power.
>
> Just as with IC engines, all available gas pressure on the piston is expanded and that work
> propels the crankshaft, regardless of geometric considerations of leverage and speed during the
> cycle. The same is true on a bicycle which approximates the working of a piston engine admirably.
> There is no inefficiency in pedaling that can be altered by invoking more muscles or operating at
> irregular velocity.
>
> I find amazing how these gimmicks keep arising and how seriously they are taken even though they
> are as much like perpetual motion machines as they can get, producing energy where the is none.

Jobst, many IC engines use offset small-end wrist pins to change the power stroke characteristics of
the engines:

http://www.fiat-spider.net/servicemanualpages/Engine/piston-rodinspecting .htm

I see where you're going with this, and remain agnostic myself on the merits of rotor cranks,
Biopace, etc. But I think these offset cranks are in use in a good many applications where there is
a desire to make the power and return strokes asymmetrical.

--
Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

 

[Meccanico Di Bi]

Test them? Why go and do something as silly as actually riding and trying them? Isn't it better to
theorize ad nauseam and create mathematical models to expound the virtues or define the weakness of
a product? C'mon! Lets just postulate, man! You say "test" like this is some kind of riders forum. I
bet you even "tested" pre 2K, Campy ders. with newer Ergo levers. Silly boy, don't you know it
simply won't work?!?!

[email protected] (Qui si parla Campagnolo) wrote in message
news:<[email protected]>...
> taylor-<< Okay, pundits, what's the verdict?
>
> http://www.cyclingnews.com/tech/?id=2002/reviews/rotor_crank >><BR><BR>
>
> we bought a pair to test(60 day money back guarantee)-we'll let ya know-
>
> Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
> (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

[Ron Hardin]

My own solution is two pedals on each side. You stand on the front ones with both feet,
all the time.
--
Ron Hardin [email protected]

On the internet, nobody knows you're a jerk.