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Post deleted by Kraig Willett
Re: Occam's Razor, Rotors and an article that may surprise some [Kraig Willett]
[ In reply to ]
KW, I always appreciate you sharing your perspective on the topics you choose to write about.
Your explanation is exactly what my not-as-scientific thought pattern settles into comfortably. Certainly, average power would give an increase in speed. That's precisely the reason I think PowerCranks work...but PC's work by increasing average power in at least one, and possibly three ways. Stick with me, I'm getting to RCs in a second!
The first way PC's increase average power is by eliminating any power wasted by the extensors to lift the opposing "recovery" leg. That's almost a "something for nothing" event...you gain some power by providing a NO resistance situation from the recovery leg. The only think this requires is some work from the hip flexors...and they can obviously be trained to do this task, and PC's do a fantastic job of providing the feedback for this training.
The second way PC's increase average power MAY be further development of hip flexor use until the hip flexors actually do more than just eliminate the recovery leg power waste, and actually have hip flexors provide some power to the pedal during the upstroke.
A third thing PC's may do to increase average power...better timing of the leg muscles during the pedal stroke...I've learned a lot about the importance of better timing by standing while on PC's.
If I think of the power curve of a PC rider, the peaks should be higher on PCs and the valley should also be higher...and therefore the average is higher...there's the power increase.
On RC's, I think the power curve also raises the average by raising the valley of the curve, but also by a slight "flattening" of the top of the curve...a longer peak power may be possible with RC's. Both of these changes in power delivery would raise the average power.
I get an understanding of these power delivery curves from the study of aortic pressure curves...these pedal stroke curves relate to peak-average-valley/power relationships very well when compared to systolic-mean-diastolic pressure/cardiac output pressure curve relationships.
At a constant systemic vascular resistance (equates to riding at an unchanging speed or gradient or wind direction), in order to increase cardiac output (equates to increasing the speed) one must raise the mean pressure (average power output) seen in the aorta. Of course, in the heart model, this is mostly done by increasing the force of contraction...just as in the bicycling model, this is mostly done by increasing the force of pedalling.
However, slight increases in cardiac output are possible by manipulation of the way the heart generates the pressure curve. A "snapping" heart has a much sharper peak, but not as high a cardiac output, and this is easily seen as a lower mean pressure...by flattening out the curve with better timing of the heart muscle firing, a lower peak, but flatter topped curve will show increased cardiac output. See how this relates to a pedal stroke curve? Of course, if you keep the higher peak pressure in this heart model, while also slightly prolonging the time of higher pressure (bulging the pressure curve slightly at the top), you get even higher cardiac output.
To be more precise, I think PC's increase the peak pressure curve by removing the power-sapping recovery leg resistance, and raise the valley of the curve by providing a better timed pedal stroke. I think RC's bulge out the top of the power curve (the area of the curve just after the peak) because they allow power to be produced at a decent value for slightly longer than normal cranks, as well as raise the valley of the curve by decreasing the amount of time spent in the zone of lowest output (I don't want to call it a "dead-spot, I think that is misleading).
(For those of you more familiar with aortic pressure curves and intra-aortic balloon pumps, I know I should be talking about left ventricular pressure curves in relation to the aortic curves, but, it brings forth the need for too much explanation between the two curve sets...mostly I'm saying that the RC's may work by increasing the pressure curve area coinciding to the area of reduced ventricular output just after the peak aortic pressure is reached.)
Together, by using BOTH PCs and RCs I think we have the best of both worlds. What is the best? A couple of percentage points more efficiency...a couple of minutes in a 40K TT?
As a Triathlete, if I could have only one of these systems, I'd have to go PC...for the running benefits. Man-o-man, did PCs have good running benefits for me!
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
Your explanation is exactly what my not-as-scientific thought pattern settles into comfortably. Certainly, average power would give an increase in speed. That's precisely the reason I think PowerCranks work...but PC's work by increasing average power in at least one, and possibly three ways. Stick with me, I'm getting to RCs in a second!
The first way PC's increase average power is by eliminating any power wasted by the extensors to lift the opposing "recovery" leg. That's almost a "something for nothing" event...you gain some power by providing a NO resistance situation from the recovery leg. The only think this requires is some work from the hip flexors...and they can obviously be trained to do this task, and PC's do a fantastic job of providing the feedback for this training.
The second way PC's increase average power MAY be further development of hip flexor use until the hip flexors actually do more than just eliminate the recovery leg power waste, and actually have hip flexors provide some power to the pedal during the upstroke.
A third thing PC's may do to increase average power...better timing of the leg muscles during the pedal stroke...I've learned a lot about the importance of better timing by standing while on PC's.
If I think of the power curve of a PC rider, the peaks should be higher on PCs and the valley should also be higher...and therefore the average is higher...there's the power increase.
On RC's, I think the power curve also raises the average by raising the valley of the curve, but also by a slight "flattening" of the top of the curve...a longer peak power may be possible with RC's. Both of these changes in power delivery would raise the average power.
I get an understanding of these power delivery curves from the study of aortic pressure curves...these pedal stroke curves relate to peak-average-valley/power relationships very well when compared to systolic-mean-diastolic pressure/cardiac output pressure curve relationships.
At a constant systemic vascular resistance (equates to riding at an unchanging speed or gradient or wind direction), in order to increase cardiac output (equates to increasing the speed) one must raise the mean pressure (average power output) seen in the aorta. Of course, in the heart model, this is mostly done by increasing the force of contraction...just as in the bicycling model, this is mostly done by increasing the force of pedalling.
However, slight increases in cardiac output are possible by manipulation of the way the heart generates the pressure curve. A "snapping" heart has a much sharper peak, but not as high a cardiac output, and this is easily seen as a lower mean pressure...by flattening out the curve with better timing of the heart muscle firing, a lower peak, but flatter topped curve will show increased cardiac output. See how this relates to a pedal stroke curve? Of course, if you keep the higher peak pressure in this heart model, while also slightly prolonging the time of higher pressure (bulging the pressure curve slightly at the top), you get even higher cardiac output.
To be more precise, I think PC's increase the peak pressure curve by removing the power-sapping recovery leg resistance, and raise the valley of the curve by providing a better timed pedal stroke. I think RC's bulge out the top of the power curve (the area of the curve just after the peak) because they allow power to be produced at a decent value for slightly longer than normal cranks, as well as raise the valley of the curve by decreasing the amount of time spent in the zone of lowest output (I don't want to call it a "dead-spot, I think that is misleading).
(For those of you more familiar with aortic pressure curves and intra-aortic balloon pumps, I know I should be talking about left ventricular pressure curves in relation to the aortic curves, but, it brings forth the need for too much explanation between the two curve sets...mostly I'm saying that the RC's may work by increasing the pressure curve area coinciding to the area of reduced ventricular output just after the peak aortic pressure is reached.)
Together, by using BOTH PCs and RCs I think we have the best of both worlds. What is the best? A couple of percentage points more efficiency...a couple of minutes in a 40K TT?
As a Triathlete, if I could have only one of these systems, I'd have to go PC...for the running benefits. Man-o-man, did PCs have good running benefits for me!
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
Re: Occam's Razor, Rotors and an article that may surprise some [Kraig Willett]
[ In reply to ]
Kraig -- interesting ruminations, thanks for posting it.
Two things quickly -- didn't get the part about correcting (discounting) both for mass [i]and[/i] weight. Help me there.
Also, would be skeptical of the 0.3% power discount for the extra lb. of weight -- at least on a flat course. This weight is pretty close to the axis of rotation (the BB); on a pure flat/straight course you accelerate twice (start/turn).
Fun stuff -- again, thanks. (Big fan of Occam's precept myself.)
Two things quickly -- didn't get the part about correcting (discounting) both for mass [i]and[/i] weight. Help me there.
Also, would be skeptical of the 0.3% power discount for the extra lb. of weight -- at least on a flat course. This weight is pretty close to the axis of rotation (the BB); on a pure flat/straight course you accelerate twice (start/turn).
Fun stuff -- again, thanks. (Big fan of Occam's precept myself.)