Comparison test done PC vs Regular cranks

Triathlon Forum
131

I’ve been watching this debate with fascination…

Question 1: You guys have debated the ‘spread the work around’ concept from the O2 cost and metabolic cost standpoint, but what about neuromuscular fatigue? Is a circular pedal stroke more fatigue resistant? If peak pedal forces are lower, can a given sub maximal power output be maintained longer?

Question 2: A while earlier someone stated that whether or not PC’s improved their cycling, they were still worthwhile due to the improvement potential they brought to their running performance. Wouldn’t someone looking for improved running preformance be better off doing hill repeats with ankle weights or something? In other words, wouldn’t they be better off sticking to something more specific to running if in fact they were looking at increasing their performance on the run?

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I understood Fred to say that the ONLY way to improve was to recruit more muscle fiber on the downstroke. I disagree with this statement.

Is there something I am missing here? if this is all it is we should stop this thread because neither of out “biases” is going to be changed because I don’t believe the data exists to prove or disprove either contention.

Frank

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Question 2: A while earlier someone stated that whether or not PC’s improved their cycling, they were still worthwhile due to the improvement potential they brought to their running performance. Wouldn’t someone looking for improved running preformance be better off doing hill repeats with ankle weights or something? In other words, wouldn’t they be better off sticking to something more specific to running if in fact they were looking at increasing their performance on the run?

I think the idea is you can improve your run while riding your bike. A killing two birds with one stone sort of thing. Very intriguing to someone like me who doesn’t enjoy running and has to budget their training time wisely.

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well this has been fun. in truth it has caused me to reflect upon how i and fred are not so entirely different. tho he is obviously a smarter dude than me i once shared his view such as i was able. actually i am fairly glad of that fact, as my relatively less stellar brilliance in fact led me to rely not on my thoughts alone but to actually accept a hearty challenge from mr day and - try the things out (!). as many know i did so in a public forum, and there was considerable risk on each side, after a fashion. while no pillar of cognition like fred, i have been known to turn a decent phrase now and again - i expected to hate the PC’s and to blast them on said public forum as a result of my trial. as an aside, while fred’s arguments do possess a certain over -wordy and graduate student-like appeal my own attacks on the product were, if i do say so myself, a fair bit more colorful and even entertaining - as i recall i even worked a blast on mr days choice in hairstyle into one during one particualrly creative spree. :slight_smile: but, again pointing out the difference between the erudite fred and myself, there was that pesky actual experience to deal with, and not just keyboarding. point in fact the PC’s completely shattered my preconceived notions of them whilst out upon the open road. funny how that happens. long story short i reveresed my position more or less entirely inside a couple weeks if not a couple rides as you know. so what? well so nothing i guess but the more i as a person regaedless of my position read fred’s ramblings the more i ask " have you actually triied them? “have you actually studied them?” because i myself have. one man’s anecdotal nothing is another man’s personal experience and i am glad i am an experiencial guy in this case. fred’s lack of field study and his vehement nothing based opposition to the things really gives me cause to wonder. as others have noted - outlandish claims by makers of perforamnce based products are not uncommon - where is fred’s indignation at every manu who claims their bike is the " best" ??? why the prolonged attack - again with out ever even trying them, against PC’s specifically? honestly when i look back to when i attacked them i can’t actually recall what my motivation was. regardless, i am very happy i was able to at least put my damn money, time, and sweat where my mouth was and commit to something other than tired rhetoric on the subjct - to put my a$$ on the line and go bust some a$$ and find the hell out. as it worked out i ate a huge pile of crow and it was the best meal i had had in a while. you can do that when you aren’t in love with your own intellect. maybe there is hope for our man fred yet - but the answer does not lie in obscure journal articles not even related to the discussion - it lies not in discussion at all - it lies on the road, with you legs screaming, and sweat on your oakleys. if fred is all that as a rider as he claims i’llbe waiting to read his review from the road - the only place that matters to this backwoods hick.

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these are definitely fair questions.

  1. i don’t know all the details about the science end of these things, and that’s not to dismiss the value of that study. my first-hand experience has been that “hammering/mashing” the pedals can fatigue the legs, for a given effort as well as from one day’s workout recovery to the next, more than pedaling more smoothly/efficiently. but i think i knew that, at least for my body, before i started on powercranks. i don’t think that a circular/round pedal stroke means that one has to apply anywhere near as much power on the upstroke as on the downstroke. don’t most people ride fastest when they are applying a ton of downstroke force and also thinking about spinning round as well as possible. once you make the initial adjustment to powercranks, you can “hammer” on the downstroke as much as ever before, but you lift slightly on the upstroke and the net result is something more smooth, and easier on the legs overall.

  2. i didn’t know whether powercranks would improve my run itself before i started on them. my mindset at the time was that if i could improve my bike leg, speed/strength/efficiency, i would end up running with at least somewhat less effort required. little did i know that i would end up a significantly faster runner. i’m not a speed demon. plenty of people can run a 15.00 5k by itself, as i am right now.

again, these are only my personal experiences. i don’t pretend to think that this is exactly how these would work for everyone, or the science behind it. for me personally, they’ve turned out to have a higher relative value for me than race wheels.

regards,

daniel.

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Philbert addressed Fred and wrote: The fact is that there is no good (or published) data to support the manufacturers claims, or the anecdotal claims of those who have improved using them. When there is such data, I will be glad to look at it. I am not arguing that they don’t work, I am arguing that there is no publishable evidence that they do. They might, in fact, work.

Thanks, Philbert. Well put. That puts you in a different category than the one I considered you so vehemently to belong to before.

The problem that many people seem to have, is that they don’t believe Dr. Day’s “40% increase in power” claims. I look at that claim as sort of like a headline, to get your attention. If you take the time to read the rest of his site, you will see that Dr. Day states that even if 40% is grossly overestimated, even a 10% increase is possible and significant. Furthermore, he states that it will take a lot of hard work, and perhaps even a long time (I think he said 5 to 10 years) to get the maximum benefits from them. I look at this section as the meat of the writing.

I don’t think this is any different than normal advertising, ESPECIALLY in light of the fact that MANY people have, indeed, reported 40% increases in power in less than a year by training on PC’s.

And, just because the exact cellular level mechanisms aren’t necessarily understood as well as the Kreb’s Cycle, with double-blind placebo controlled studies, the successes of these people are real. I’m VERY interested in the science of exercise physiology, and I’d love to see some studies done. The only thing I can do is set up crude experiments for myself, post the results, get suggestions on what to do better or different the next time, and keep on examining my performance. MY performance is the only thing that matters to me. I have nothing to gain or lose either way…I’m just searching for what causes me to gain performance…defined by faster tt’s, faster running, or tt’s at lower heartrate and running at lower heartrate.

It takes less than 2 months to decide if they work, or you can opt to get your money back. I’m not familiar with any other sports product manufacturer that will stand behind their product like that.

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I have analysed this to try to figure this out. It certainly was an unanticipated benefit but when essentially everyone started reporting HUGE increases one has to ask why.

PC’s is the only way to force yourself to lift each knee about 14 inches 4-5,000 times an hour 9with weights attached in the form of pedals. Watch people doing stair master, they hardly ever climbe more than 6 inc h steps. Running stadium steps, 6-8 inch steps and you have to stop when you get to the top. Hill repeats, you have to stop when you get to the top and come back down.

PowerCranks, 14 inches time after time after time and you just keep going and going and going. It beats anything you can do on the ground in the way of drills.

And, Alberto Salazar told me he though they would also encourage good form by helping with heel kick up.

Anyhow, that is my analysis.

Frank

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…don’t forget that the running benefits, if there are any (and I think the running benefits begin almost immediately), are accomplished without the pounding (especially in the lower leg/ankle/foot areas) accompanied by actually running. I still make sure I get out there and run…there is no substitute, and those lower leg/ankle/foot tissues must be “hardened” or allowed to adapt to the forces that running imparts.

But, I aquired an ability to pick my knee up much easier when running, and I think this knee lift is what is responsible for my faster running. High knee lift certainly seems to be a characteristic of speedy running. I no longer give knee lift a thought, even at the end of my long runs.

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After reading a lot of the discussion about Power Cranks, I wanted to “add” my thoughts. I do not own a set of these cranks, and don’t think I could justify the cost. OK I can justify the cost…I wont be able to justify the cost to my “accountant” :wink: I hope that my thoughts on this come across clearly, since I know I will be flamed by some of you.

Let us start by dissecting pedaling with the approach of simple mechanics. Lets just say that the leg can apply a downward force to the pedals. Surely the leg cannot apply a steady even vertical force to the pedals. This force is not purely on/off. I’m sure one the physiologist will state this to be correct. The force (per leg) is thus applied in a wave form. Per revolution of the cranks the force is applied during the rotation of 0 - 180 degrees with maximum applied at 90 degrees, and 0 force applied from 80 - 360 degrees (lets for the moment pretend that the back leg is not “resting” on the pedal). Agreed?

The force is applied downward, and as such the crankarm leverage is not constant, with respect to this force. The effective crankarm length changes with a sine wave form. At 0 degrees (12:00) the effective crankarm length is 0, and at 90 degrees (3:00) the effective crankarm length is the full length of the arm. Surely we can all agree on this as well.

If we apply the leg force to the effective crankarm length, the resulting torque to the Bottom Bracket (BB) is an amplified wave form. The peak torque occurring (hopefully) at 90 degrees. Simple physics and math. Lets not split the hairs, in principal this is the mechanics agreed?

Now lets map this out. We have 0 - 90 degrees with increasing torque being applied to the BB. 90 - 180 has decreasing torque being applied to the BB. 270 - 360 has no torque being applied. This is due to the torque as applied by a single leg with downward effort only. Surely, we can agree that this would be the result.

With applying “only” a downward effort, during 50% of the rotation no torque is being applied. What we end up with is basically only the positive portion of a sine wave.

Now lets say that you can produce 200 watts while pedaling. You gather this information by using a Power Tap, Computrainer, or any other of the methods available. This power measurement is an RMS rating. (kill me since I forgot what RMS actually stands for). Simply put, it is the average power output. Your actual power output is not constant. It is a pulsing wave form (see the lengthy discussion above).

Now someone with more up to date math skills. Since we are discussing a single leg right now lets take half of that - 100 watts. How much PEAK power is required to produce 100 watts RMS with the wave form as discussed? Sum of the area under the curve divided by time if my memory is still good. Half of the time in this wave form has no power being produced. So could one of the more “schooled” ones out there run the numbers for us. How much would the PEAK force be to produce 100 watts RMS verses what tangential force would be required (to keep the torque constant throughout the rotation) to also produce 100 watts RMS?

The inclusion of both legs will yield the summation of both resulting power curves, and the resultant curve will still be pulsing. I agree that the difference between the PEAK power and the RMS power will be lessened. But do you want to go back to the beginning of the discussion and look at the power value for the 180 - 270 degrees. I had this at 0. Any resistance due to this leg increases the amplitude between the positive PEAK and the overall RMS power rating.

The benefit of the Power Cranks may simply be that it requires a more constant power output. The PEAK value may not change using PC’s but the valleys would. These points would be higher on the power curve. This then manifests itself in improved RMS power.

Doesn’t that trainer make that whir whir whir sound when you ride? Why do think that is? The PC’ers have consistently stated that their trainers now have a wwwwhhhhhhiiiiiirrrrrrrrrr sound. Lets see, one is a pulsing sound the other is more smooth/even sound.

I’'ve written too much already. I will gether up my flame suit and prepare for the replies…

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For myself as a forum lurker, this thread was fun to watch develop. Most entertaining. You guys seem to hold your personal choice in cranks right up there with motherhood, apple pie, and the American flag.

I’m going to stay out of the PC vs. non-PC debate. In my mind, the benefit of PC’s or lack-there-of depends on the individual user and his weaknesses. What did get my attention though was the side debate on the value vs non-value of a circular pedal stroke or the ‘spread the work around’ concept.

Let me lay out the following premises/assumptions:

  1.   A higher cadence, smaller gear pedal stroke is more sustainable and induces less neuromuscular fatigue for a given sub max power level. 

  2.   As a cyclist’s ability to put sustainable power to the pedals increases, his optimal cadence to deliver that increased level of power output also increases. 

  3.   The ‘square’ pedal stroke of even the most powerful masher is cadence limiting.  In other words, no matter how powerful the downstroke, if the rider can’t ‘get his foot ‘out-of-the-way’ on the upstroke, cadence is limited.

Therefore, in my mind, how the rider puts the force to the pedals is immaterial. Whether it’s through a more powerful downstroke or through the possibly mythical contribution on the upstroke. But what is important is that the rider develop the ability to at least ‘get his foot out of the way’ on the upstroke. If he doesn’t, he may not reduce his max power output, but he may limit his ability to sustain the highest possible power output for an extended period of time. Simply stomping on the pedals may not necessarily limit power, it may even enhance maximum attainable power, but maximizing sustainable power requires the rider to at least be able to unweight the pedal and not impede the pedal in any part of the circle (as this is cadence limiting).

Just some food for thought. I’m wondering whether either my assumptions or my conclusion is wrong here.

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Mr. Curious,

I am in agreement with ALMOST everything you said. My disagreement is with your assumption #1. As anyone who has ridden a pair of PC’s knows a higher cadence is not more sustainable. the reason is it takes a lot of energy to make the pedals go round and that energy increases with the square of the cadence. This means the power lost in the pedaling action increases with the cube of the cadence. why does your typical couch potato grand mother ride her bicycle with a cadence of 45 or so, because relatively more power gets to the wheel the lower the cadence so, with limited power available, lower cadences are relatively more sustainable.

Because your assumption #2 is correct, athletes who generate more power ride at higher cadences than your grandmother does riding around the block.

Frank

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OK, I’ll agree your physics is valid. Probably why we don’t all pedal at 200 rpms. But there’s a tradeoff. The physiological aspect. Repeated contractions at more of a sub max force level are more sustainable for a given total volume of work performed than fewer contractions per unit time at higher force. Probably why we don’t all pedal at 10 rpm.

All else being equal, I still believe lower force, higher cadence pedalling causes less stress to the working muscles, hence it’s both easier to sustain for a prolonged effort and easier to recover from between efforts.

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We don’t pedal at 10 rpm because power is force times distance per unit time. at 10 rpm the distance the pedaal travels in one second is not very far so to get to high powers requires forces beyond the ability of the human leg.

So you are right, it is a trade off. We trade some in efficiency so we can achieve higher powers. What we want to do is trade off as little as possible and those who try toride at high cadences are losing more than they are gaining.

Frank

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Tell that to Scott Moninger, who rode for 1 hour at 97-98% of VO2max in the study of Coyle et al. (while not unweighting the rising pedal).

There are some really good cyclists out there who have never even heard of PowerCranks. In fact, before PC’s that was all of them including Merckx, LeMond, Armstrong, etc. The only three further questions in my mind are:

  1. Can they get even better?
  2. How much better is possible?
  3. What is the best way to achieve that improvement?

I think the answer to those questions is:

  1. Yes.
  2. 25-50% sustained power increases.
  3. training exclusively on PowerCranks for 3-5 years.

Frank

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One would have to assume he’s also driving his knee up and forward like a sprinter, too at those cadences. Not disagreeing that the power with those guys comes from the downstroke, but they’re not letting their foot drag along on the upstroke either. That would limit cadence. That’s my only point.

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Simply stomping on the pedals may not necessarily limit power, it may even enhance maximum attainable power, but maximizing sustainable power requires the rider to at least be able to unweight the pedal and not impede the pedal in any part of the circle (as this is cadence limiting).
Tell that to Scott Moninger, who rode for 1 hour at 97-98% of VO2max in the study of Coyle et al. (while not unweighting the rising pedal).

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Wow - since Moninger’s VO2max was 73 mL/kg/min, then you’re saying that use of PCs would raise this to 91-110 mL/kg/min. Damn, Frank - training with your cranks is better than injecting yourself with EPO!!

No, I am saying I think I can raise his power. some of that will come from increasing his VO2 max but most, I believe, will come from improving his efficiency.

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Oh, well, I can’t get my edit in there on the last post. My question was, How do we know he didn’t unweight his rising foot? Was there a pressure plate sensor on his pedals or something? I’m simply not familiar with this study. Thanks!

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just in the interst of putting this thing in the record book. . . . . . i have to chirp back in an say this business of track riders not endeavoring to, and in fact ACTUALLY not pulling up is truly one of the most ridiculous thing in any cycling argumaent i have ever heard. at every track event you will see some poor schmoe ripping his foot from the pedal on the upstroke. you will still see guys with toeclips and double laminated leather/nylon straps you could tow a ship with with because they rider doesn’t trust the pedalls from releasing on the UPSTROKE. i am sure mr Not would love to inform these guys that their leg did not just leave the pedal on the upstroke at all - and that it in fact left on the downstroke because that is where all pedalling force is generated. gaawwwwd. come on now !! talk about from the subline to the ridiculous.

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of course, IMHO PC’s aren’t actually about “pulling up” like a track rider at all - it is just osition as a frame of reference from the extensor crowd that i find is humourously and completely disproven by even casual observation. . . . . .