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PostPosted: Wed Mar 28, 2012 1:26 am 
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http://www.worldacademicunion.com/journ ... aper04.pdf

New study looking at non-circular rings for 1km effortS - could be of benefit.

This study has different findings to those which have used longer TT efforts (~16km) and found no benefit to non-circular rings.

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PostPosted: Wed Mar 28, 2012 3:45 am 
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:thanx:


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Posted: Wed Mar 28, 2012 3:45 am 


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PostPosted: Wed Mar 28, 2012 3:35 pm 
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note to self. use circular chainrings for majority of race. go back to team car and swap to rotor rings before last 1km sprint.


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PostPosted: Thu Mar 29, 2012 12:48 pm 
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very interesting and informative study, especially the loss of performance AFTER the switch back to round rings after the main test.


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PostPosted: Fri Mar 30, 2012 4:59 am 
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Interesting study. I really wish they had used more subjects though.
It would have also been nice to have a control group. Perhaps the subjects were becoming more familiar with the protocol of the TT as testing went on, and thus better able to pace themselves. They may have also become burned out or overtrained towards the end of the study, when the traditional round rings were replaced.
If these results hold true, rotor rings certainly seem like an investment to consider. A 6% increase in power for a 1km TT is nothing to laugh at.

edit: Anyone know how many guys on Garmin ride Rotor rings? Considering that Rotor is a sponsor of the team, I think they would be one of the few teams that would actually encourage riders to use them.


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PostPosted: Fri Mar 30, 2012 5:11 am 
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Also the riders knew they were on Rotor rings. A psychological benefit could be possible - and could explain the "loss" of power once back on regular rings.

The study I referred to about seeing no change in the use of non-circular rings was blind... or at least as blind as you can make odd- shaped chainrings (this was done by a cardboard "cover" which prevented the rider from seeing the chainring.)

But yes, psychological or not - that's a decent boost! Countdown till the UCI bans them, in 3, 2, 1.....

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PostPosted: Fri Mar 30, 2012 6:11 am 
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Alex Simmons noted that Racermate, whose software was used for data collection, said that non round chainrings may affect accuracy of power readings.

Apparantly, you can achieve different speeds for the same power if you change the way you pedal on a Computrainer.

I hope I remember that right and would like to mention that I haven't used either.

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PostPosted: Sat Mar 31, 2012 11:20 am 
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Ypsylon wrote:
Apparantly, you can achieve different speeds for the same power if you change the way you pedal on a Computrainer.


Yes, what he's saying is this: If the computrainer needs 400W to turn its roller at 25mph that is the same whatever chainring you use. Physics, gravity and friction still apply. Buy your crank-based power meter may show 395W instead of 400W at 25mph.

This is because changing the to a non-round ring because changing the chain ring introduces calibration and physical differences which are not accounted for properly in the power meter, so it looks like you are going faster for the same power. Likely this is because the non-round ring has a different stiffness to the round ring and also gives a different acceleration profile for a given pedalling force. So when the power meter samples force at high frequency and integrates it back to power this introduces some measurement differences.

If one could set up a study to somehow show time attained over a course, I'm pretty sure there would be no difference between chainring x and chainring y. I think the results of time trials show that pretty conclusively - qed.

Cycling innovations which promise to give you something for nothing should be regarded in the same way as investments which promise high returns with no risk: Too good to be true.


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PostPosted: Sat Mar 31, 2012 11:36 am 
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The reason crank based powermeters report power differently with non-round rings is they assume constant velocity throughout the pedal cycle, which is an incorrect assumption with non-round rings.


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PostPosted: Sat Mar 31, 2012 7:22 pm 
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Neither it is a correct assumption with round chainrings. Actually, I wouldn't be surprised if feet angular velocity is smoother with ovalized rings.


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PostPosted: Wed Apr 04, 2012 5:26 pm 
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Nick Legan posted this comment on a photo for an article about PR bikes:
Half of Garmin's classics squad is now using Rotor's oval chainrings, like these time trial versions on Tyler Farrar's R3.
http://velonews.competitor.com/2012/04/ ... aix_212110

Interesting to hear that many guys are using them now.


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PostPosted: Wed Apr 04, 2012 10:26 pm 
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jmechy wrote:
Nick Legan posted this comment on a photo for an article about PR bikes:
Half of Garmin's classics squad is now using Rotor's oval chainrings, like these time trial versions on Tyler Farrar's R3.
http://velonews.competitor.com/2012/04/ ... aix_212110" onclick="window.open(this.href);return false;

Interesting to hear that many guys are using them now.


That is not an oval chainring - it is a round chainring with oval graphics.

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PostPosted: Wed Apr 04, 2012 11:11 pm 
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jmechy wrote:
Nick Legan posted this comment on a photo for an article about PR bikes:
Half of Garmin's classics squad is now using Rotor's oval chainrings, like these time trial versions on Tyler Farrar's R3.
http://velonews.competitor.com/2012/04/ ... aix_212110" onclick="window.open(this.href);return false;

Interesting to hear that many guys are using them now.



Even if it were oval, a team using it's sponsor's equipment is no indication of effectiveness whatsoever.

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PostPosted: Thu Apr 05, 2012 3:04 am 
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Its a Q-Ring. He only uses them for certain stages/races. He used them in the Vuelta and the Tour last year on climbing days if you can find good screen captures.

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Posted: Thu Apr 05, 2012 3:04 am 


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PostPosted: Thu Apr 05, 2012 9:59 am 
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KWalker: Then the picture must be wrong.

AFAIK it is this one:

As round as round chain rings can be.

http://www.cyclingnews.com/features/pho ... ers/166443

Image

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