Rotor elliptical cranks

London knight

One of my teammates recently installed rotor elliptical cranks on his roadbike in an effort to improve his timetrialing (ie. removal of the deadspot when pedalling). I was wondering if there is any evidence that these type of cranks can improve performance?

Sillyoldtwit

Here we go again! Tyson

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London knight

I take it this has been a topic on old forums?

11ring

In short, yes, but not because of the removal of the dead spot per se, but because of the reduction of its negative effects.

This is a reasonable explanation/hypotheses for the fact that "pedalling circles" does not improve performance, but Q-rings and cranks DO.

Teaching yourself to spin in circles and pull up with normal rings REDUCES efficiency as your hamstrings are forced to create more force than they want to, i,e this technique INCREASES the demands on the hamstrings, which are forced to recruit type 2 fibres and then deplete glycogen and create lactic acid.

Q-rings and Rotor cranks INCREASE efficiency and decrease lactate production because they REDUCE the forces needed to be produced by your muscles during the deadspot, ensuring mostly type 1 fibres, which are more efficient, are capable of producing the forces demanded.

It is a legacy of the failed Biopace rings and a tradition of weight obsession which has restricted the uptake of this technology, which IS performance enhancing. See the Rotor websited link to published studies:

http://www.rotorbike.com/2006/science.htm

acoggan

There is no direct evidence to support this claim.

11ring

The study below found a significant increase in maximal power outputs and ability to sustain high intensity aerobic efforts in cyclists using Q rings as opposed to round rings. There are also other published works which suggest a performance enhancing effect from their use.

http://www.rotorbike.com/2006/pdf/q_ring_study.pdf

I am not aware of any such study which shows any improvement through changing the way that force (torque) is applied through the pedal stroke using round rings.

acoggan

Allow me to be more specific: there are no published studies showing that Q rings or Rotorcranks improve performance.

As for this unpublished preliminary report, I find it interesting that power was measured using a Computrainer, which like the SRM ergometer assumes a constant angular velocity when calculating power. Such an assumption obviously doesn't hold when using non-round chainrings, which is why the SRM tends to overestimate power when used with such products - the Computrainer could very well be the same.