Who has Powercranks - Page 3

Quote:

Originally Posted by wilmar13 ...but unfortunantly the laws of physics makes this a net sum zero gain. it doesn't matter whether you use the down stroke of your left leg to lift your right leg, or use muscles from your right leg to do the deed, your body expends the same energy...

let me get this straight, if my downstroke leg is fighting my upstroke leg (because i can't shut the upstroke leg off completely) then that's the same net energy expenditure as compared to a downstroke leg that is AIDED by a lifting upstroke leg at the same wattage?

i think you might want to brush up on your "laws of physics."


i've won races on $2000 carbon aero wheels and i've won races on heavy non-aero mavic classics pros.....and each result would have been the same regardless of which wheel i was on. expensive aero wheels make very little difference for the average amateur racer who spends the majority of his race in the pack or paceline where wheel aerodynamics are nearly useless. but they sure look cool and that's why i'm keeping mine!

super secret PC user for the past 3 months. interesting thing. i shut my season down early due to birth of child and got started with the PCs at that time. my training volume has gone way down, no racing, no hard training, no intervals or hill repeats, but i've felt stronger than at anytime during the season. i have a few TT spots around town that i've used monthly for the past 4-5 years including 5 mile TT's on my rollers (to check my fitness and compare to certain times of prev yrs) and i've set records on all of them in the past month (using reg cranks) since i've adapted to the PCs.

to be honest, the advantage i've seem already is so great that i hope people listen to you and stay away from them. keep it up!!

I absolutely love the "science is god" crowd. If you can't boil something down in a triple-blind-placebo-controlled-randomized trial, then it can't possible work!! Problem with this thinking is that such studies are often contradicted over time (JAMA july 05 review: showed that ~30% of all studies submitted to JAMA during 1990-2003 were either contradicted or overblown. Dec 04 Amer J of Med found that 100% of drug industry-sponsored studies were favorable to the products use!!. Paxil users are 8X's more likely to commit suicide than placebo users. Vioxx, Celebrex, Bextra, etc., all had vast research performed prior to release, yet they've killed 10s of 1000s. I could go on.)

Studies aren't the end all-be all that we'd all like them to be.

Back to #9. I'm not exactly sure which physical laws are governing your universe, but in mine, if i'm pushing down with the upstroke leg (cuz i can't shut it off) then i'm robbing alot of power from my downstroke leg, resulting in a significant loss in net power output. If, on the other hand, i can go so far as to train muscles i haven't used before to pull up on the upstroke then i'm adding to the net power output of the unopposed downstroke leg.

But i also understand DNA and how unbelievably complex it's structure is, and that as a result DNA cannot assemble itself by random chance (or it's amino acids for that matter), no matter how much time you allow. So what do I know?

Even the most ineffiecient pedaler does not apply muscular force downward on the upstroke... we are talking about lifting the leg. It doesn't matter whether you lift with the upstroke leg, or push harder with the downstroke leg to push the upstroke leg over, it expends the same energy... I am not introducing anything new here... unless you can show me a patent for a perpetual motion device you may want to use a little more caution when telling others to brush up on physics especially considering we are talking about the most basic newtonian physics taught to high school kids...

Agreed it is 99.9% rider and wheels will make little difference, my earlier comment was related to the fact that it can be proven aero wheels give you a small but measurable boost in speed (at speeds above 25mph).
Please go back and reread what I posted. I have never said they were junk, the contrary in fact. IMO you will not gain any power, but I have no doubt you will gain pedaling efficiency (because of very complicated physiological factors, not because of physics), probably big time. If nothing else you will have more muscles to recruit to boost endurance. But my original point stands... I can gain many of the benefits (assuming there are any) of power cranks without spending anything.

If you "push down" on the upstroke you are retarded, do you drive while applying the brakes too?

Let me try to help you out here, before you continue to give more ammo to the naysayers you, for some reason, think I am a part of...The negative pedaling pressure you are mentally thinking of is the weight of your leg. You do not push down with both legs at any point in the circle no matter how poor you are at "spinning circles". I will repeat it once more just to waste time:
It does not matter if you lift with your upstroke leg, or push harder with your downstroke leg, the energy required is the same. There is no free lunch.

I see no way that power cranks would ever make you are worse cyclist(except maybe reduction of training in the beginning), and many ways they will make you better... but you do not use less energy in a physical sense... any gains are purely physiological (proven or not) and/or psychological.

Response:
A. Says who? You? Are you absolutley sure that the muscles from the downstroke leg shut off completely during bottom dead center and then as it begins and completes the upstroke? There is no residual contraction of those muscle groups? Show me the studies. Remember, "If you "push down' on the upstroke, you are retarded."
I've heard a number of well-known cycling coaches speak of this very problem in the amateur cyclist, especially the 'less-coordinated' athlete.

B. You are correct about the energy expenditure. But I'm more interested in energy expenditure per given power output. If power output is robbed by either fighting or even just lifting, the upstroke leg, then net power output is less per given energy expenditure and you go slower. Simple. Not sure if that falls under Newton's first or second law of motion, but I guess I'm just not up on my high school physics...

C. Tell me of these "complicated physiological factors." Or do you simply mean that adding upstroke force to the downstroke force equals an increase in net power output?

D. How? Be specific, beyond "lose weight and follow a training program."

E. I use them casually right now as I'm still adapting to them, and I've already seen BIG improvement (without losing weight or a training program). But you've got me thinking.....if i lose a few pounds and train hard with these things over the winter.....hmmmm. Please do not buy Powercranks, they suck. And they'll make your knees hurt. And you'll wind up with an STD. Stay clear, buy wheels instead, they've been shown to help in double-blind-espresso-controlled-university-funded-studies.

BTW, in C (above) you said "I have no doubt you will gain pedaling efficiency, probably big time" and then in D (above) you said, "I can gain many of the benefits (assuming there are any) of power cranks without spending anything." So which is it?

Here you go: http://www.midweekclub.com/articles/coyle91.pdf It shows that amateur cyclists actually have less downward force on the pedals during the upstroke than elites... and one of the elites in the study happens to be a 7 time Tour de France winner. Now this study doesn't in any way put an end to the argument about PCs but I think you will find it proves my point about downward force on the upstroke. Even at 200 rpm a healthy adult would have no trouble controlling the firing of leg muscles (if they can't they better not be driving a car or playing video games)... no I am not an expert on any of this, just sharing the info I learned during many many hours of research into them before I almost bought them and giving my $.02 based on that. I did a quick search with no luck, but about two years ago there was a really technical and educational thread with Andy Coggen, Jobst Brandt, Frank Day (the inventor), and several others way more knowledgeable than I arguing their opinions that made me rethink the cost(effort)/benefit of them.


Maybe you are a freak, but fact is almost every trained cyclist is limited in power output by the cardio system, not strength. Why it fails the laws of motion is that you are thinking you are gaining something by lifting with one leg vs. pushing harder with the other... besides your muscles are not what determines your power output, you already have enough "strength" to do this without even training.

I am an engineer with an interest riding faster and my understanding of physiology is limited to this only. What I was getting at was that many people use this pulling up garbage as if they have gained something for free. But I think the advantage comes from being able to distribute the work over more muscles, therefore being able to ride longer/ more efficiently. Lets be careful when talking about energy expenditure (in a physiological sense) vs. energy req. (in a mechanical sense). energy req will remain unchanged with powercranks, but I certainly agree that energy expenditure at a fixed (but less than maximal) power level can be reduced with a better pedal technique... but there are a lot of experts that will disagree with that premise, sift beyond the rosy user testimonials and you will see...

No I meant one legged pedaling in the off season and purposely pulling up/pedaling circles while cycling.

Yeah and there have been studies showing dramatic gains for athletes taking extended rest periods after hard training too. I guess I can understand why you would be so defensive after spending the money on them... but if you really look at what I said I have never been negative towards PCs, only objective.
Leonard Zinn says: "There is no question that Power Cranks improve a rider's upstroke. I have ridden with them quite a bit and am not eager to use them again, but that is not because I don't think they would improve my pedaling. It's just that I only ride for fun any more, and I find the ride less fun when I have to constantly work, even when coasting. If I were still racing, I would probably want to have a bike set up with them."
I am just a terminal Cat 3 nobody, and while I think there are advantages to them, I can't justify the $$$ and more importantly the year long commitment they require, for myself. Also the clutch is designed for relatively low torque, I am a 6'4" 200 lb power rider that can generate 1300 watts at 80rpm, I was scared off by the "slippage" issue that some riders report. You can have at it, I never took issue with PCs being an advantage, only that you don't gain something mechanically by "pulling up"

I don't want to get into the argument of if they are BS or they will turn you into a pro, so I am trying to be diplomatic and say that I believe there are benefits to them without opening myself up to the "show me proof" criticisms from others who think if it ain't broke don't fix it...

BTW: if you signed up to cycling forums just to troll me into wasting 20 minutes of my day it worked

not trolling. they're working for me great so far and i thot i'd share. if they hadn't, i'd ebay 'em or send 'em back. i'd certainly stop using them. plus, it's not like i have anything to prove to you, wherever you are. let me read this study and i'll get back but i'm sure i've seen a more recent one that showed the opposite, but i've been wrong before.

not defensive. fortunately i'm in a position where the $$ wasn't a problem for me. i don't have to justify the expense to this forum, whether they work or not.

for what it's worth, i've done monthly field tests (TT's inside and out with conditions as similar as possible) have been done monthly to chart my form. they've been done at my strongest and weakest points of the year, every year, since 2001. i've recently set PRs on all 3 of them.....could be the rest but...i wouldn't expect REST to continue have this affect after 3 months off. at some point you'd think i'd start to lose something....

or maybe i'm a freak.

enjoying the debate, i'll be back.

[QUOTE=wilmar13]Here you go: http://www.midweekclub.com/articles/coyle91.pdf It shows that amateur cyclists actually have less downward force on the pedals during the upstroke than elites... and one of the elites in the study happens to be a 7 time Tour de France winner. Now this study doesn't in any way put an end to the argument about PCs but I think you will find it proves my point about downward force on the upstroke.



not to nitpick, but the study says the riders were recruited in the spring of 1988 (p.94) and the study conducted sometime after that. then lance would have been what, 17, at that time? so he's Subject F or Subject N? just wondering.

p.99: Interestingly, the subjects of group 1 produced the larger propulsive torques by creating significantly larger forces in the vertical direction on the pedal during the downstroke and by not attempting to pull up on the pedal during the upstroke.

p. 101 is worse.

To be honest I don't know... FWIW Coyle did continue studying Armstrong's power output and pedaling cycle for several years but I don't have time to look for it right now... google is your freind

It really shouldn't matter to you now, I mean you already have them and feel they are working for you. Ignorance is bliss and it is to your advantage to think PCs are a secret weapon as the mind is much more powerful than the body. If you really really spend some time looking at arguments for and against (the intelligent ones that is) PCs you will find some very powerful against and not many for... there was a study done (probably the one you are referring to) with power cranks that showed the PC group to be able to make the same power at a lower HR vs the control group. Serious sports scientists ripped the study for a bunch of technical study protocol reasons. Neglecting that, it showed that they could make the same power (below LTH) more efficiently (peak power did not increase). Critics claimed even this could not even be attributed to PCs because it has already been proven that lower cadences are more efficient (endurance wise, your muscles can uptake glycogen faster at higher cadence) and the PC grouped trained at lower cadences. I think Frank shoots himself in the foot with his ridiculous 40% power increase claims and the skeptics come out of the woodwork. If he didn't do this, perhaps some of Sports Scientist community would try to find some truth in the benefits of PCs to back up the anecdotal evidence that exists, rather than claim it as all BS.

But like I said, I believe they will help you at least be able to ride more efficiently and save energy/strength for when you need it if nothing else, even if there is no "rigorous study" to back it up.

so put these on ya bike and ya ride like a circus clown huh? as per the video on the site lmfao

no thanks i will stick to both legs going round in the time honoured fashion...

gimmics are for geeks

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Wide load!!

wilmar13,
the more i read, the more trouble i find with this study. also having a phd exercise phys friend of mine looking at it. he doesn't like it either. i'll get back to you soon.

hey penguin,
true that i look and feel like a clown while i'm on the PCs....but now i'm faster on reg cranks. and you're still slow.

Well don't waste too much time on it... basically it is one of the few studies done on pedaling that is "rigorous" enough to satisfy the academics and that is the only reason I posted it. Basically all you can take from it is that elite cyclists make more power with a worse pedaling stroke than the competitive amateurs. You could argue that maybe the elites could improve their advantage even more by copying the circular pedaling of the amateurs...which is the point of PCs.

Quote:

Originally Posted by wilmar13 Well don't waste too much time on it... basically it is one of the few studies done on pedaling that is "rigorous" enough to satisfy the academics and that is the only reason I posted it. Basically all you can take from it is that elite cyclists make more power with a worse pedaling stroke than the competitive amateurs. You could argue that maybe the elites could improve their advantage even more by copying the circular pedaling of the amateurs...which is the point of PCs.

I agree, this study has very little to do with what we are talking about. And the more I (and my PhD exer phys friend) look at this particular study, the weaker it looks as far as it relates to our discussion. But I’m not an “academic” so……


Now forgive me for bouncing around here as I’m in a bit of a rush, but without getting too much into it, the problems arise when the authors make such statements that group 1 cyclists produce more torque “….by not attempting to pull up on the pedal during the upstroke…” (p99).


There is absolutely no evidence for this because the authors did not test physiologically equal cyclists to one another before and after training half of the group to employ more efficient pedaling techniques and keeping the other half as control.

[Interstingly, they state that group 2 cyclists were “more efficient” because they DO pull up on the upstroke. hmmmm]

The truth is that (stronger) group 1 cyclists produce more power despite the fact that they are less efficient than the (weaker) group 2 cyclists. Upstroke force was not one of the 5 factors listed on p. 103 as indicators for higher propulsive torques

In fact, the authors basically compare apples to oranges here. Group 1 produced more downstroke torque than group 2 because (from p.103):

1. Group 1 had higher % of subjects with type 1 muscle fibers
--1 of 9 group 1 riders with type 2 fibers
---5 of 6 group 2 riders with type 2 fibers
---- this alone can explain the differences in torque applied over 40 k TT…group 2 riders were probably anaerobic for most of their TT whereas the better, stronger group 1 riders were able to generate greater power aerobically.
2. Group 1 possesed a 23% higher muscle capillary density
3. Group 1 displayed 29% higher myoglobin concentration
4. Group 1 also appeared to be better trained based upon the observation that LDH activity was lower and…
5. ...citrate synthase activity tended to be higher.


CONCLUSION: better-trained and more powerful cyclists can produce more torque over a 40k TT than lesser trained, weaker cyclists. Really? Wow, thanks. But I think you’ll agree that you really can’t take much more than that conclusion from this super rigorous trial.


The authors lose their minds when they state on p. 101 that their results “emphasize the importance of the downstroke for creating the propulsive torque and the relative unimportance, especially in the “elite-national class” cyclists, of the upstroke for creating propulsive torque.” This statement is, at best, silly. There is absolutely no evidence for this, merely the observation that the stronger cyclists fail to pull up on the upstroke. They should not make that statement without comparing apples to apples. You must compare group 1 cyclists to group 1 cyclists, with half of them trained for some period to pedal more efficiently (one-legged drills or PCs), and the other half as control, with pre and post testing. Then you can measure whether or not pedaling efficiency, or upstroke force, has anything to do with overall torque.


Funny thing is, a study investigating just that very thing was done just 2 yrs ago. Check it out.

Entrez pubmed ResultsItem 1 of 1

1: J Strength Cond Res. 2003 Nov;17(4):785-91.Related Articles, Books, LinkOuthttp://www.ncbi.nlm.nih.gov/entrez/q...pubmedicon.gif
Effects of short-term training using powercranks on cardiovascular fitness and cycling efficiency.

Luttrell MD, Potteiger JA.

Department of Health, Sport and Exercise Science, University of Kansas, Lawrence 66045, USA.

Powercranks use a specially designed clutch to promote independent pedal work by each leg during cycling. We examined the effects of 6 wk of training on cyclists using Powercranks (n=6) or normal cranks (n=6) on maximal oxygen consumption (VO2max) and anaerobic threshold (AT) during a graded exercise test (GXT), and heart rate (HR), oxygen consumption (VO2), respiratory exchange ration (RER), and gross efficiency (GE) during a 1-hour submaximal ride at a constant load. Subjects trained at 70% of VO2max for 1 h.d(-1), 3 d.wk(-1), for 6 weeks. The GXT and 1-hour submaximal ride were performed using normal cranks pretraining and posttraining. The 1-hour submaximal ride was performed at an intensity equal to approximately 69% of pretraining VO2max with VO2, RER, GE, and HR determined at 15-minute intervals during the ride. No differences were observed between or within groups for VO2max or AT during the GXT. The Powercranks group had significantly higher GE values than the normal cranks group (23.6 +/- 1.3% versus 21.3 +/- 1.7%, and 23.9 +/- 1.4% versus 21.0 +/- 1.9% at 45 and 60 min, respectively), and significantly lower HR at 30, 45, and 60 minutes and VO2 at 45 and 60 minutes during the 1-hour submaximal ride posttraining. It appears that 6 weeks of training with Powercranks induced physiological adaptations that reduced energy expenditure during a 1-hour submaximal ride.

Publication Types:

• Clinical Trial

PMID: 14666944 [PubMed - indexed for MEDLINE]


I'd be interested to see what happpened after 6 and 12 months.

Anyway, I'll use this study to help me with my "ignorance is bliss" thing. You know what? I think I've gotten even stronger just since I read this 2003 study again. You're right about the power of the mind!!

Dr. Spinner, (sounds like you are an MD or close)

I have been in a couple of recent big PC "debates" with the usual naysayers over on the cycling training forum (check out the "Poor Man's PowerCranks" and the "Where does Power Come From" threads if you are interested.

Anyhow, it sounds like you held your own but I thought I would throw in a couple of more "study" thoughts.

Regarding the Coyle study brought up here.

40. Coyle EF, Feltner ME, Kautz SA, Hamilton MT, Montain SJ, Baylor AM, Abrahams LD, Petrek GW: Physiological and biochemical determinants of elite endurance cycling performance. Medicine and Science in Sports and Exercise 23:93-107, 1991.

Everyone points to this study as proving that "just pushing harder" is the key to becoming an elite cyclist. Yet one of the main differences between the groups is the elite group had two more years of aerobic athletic training than the lesser group. I think the only thing that can be taken from this so called study is "train more, get better".

Coyle did another study that shows the exact opposite of the "just push harder is the key to getting better".
43. Kautz SA, Feltner ME, Coyle EF, Baylor AM: The pedaling technique of elite endurance cyclists: changes with increasing workload at constant cadence. International Journal of Sport Biomechanics 7:29-53, 1991.

What does it show? As these elite cyclists get close to their maximum power what do they do? They pull up on the back stroke!!! Just push harder indeed.

Then Coyle has a later paper looking at the progression of Lance Armstrong.

86. Coyle, EF. Improved muscular efficiency displayed as 'Tour de France' champion matures. Journal of Applied Physiology. 98: 2191-2196, 2005.

The title of the paper should really be "Improved pedaling efficiency displayed as 'Tour de France' champion matures" as that was the only variable that changes as his power continued to increase. These guys are such narrow thinkers that they thought that the only way this could happen would be if he was able to change his fiber type in his legs because of his training. Of course, they surmised this without a single biopsey. Lutrell, as you know, has shown it is possible to change pedaling efficiency using "simpler" methods than trying to change muscle fiber type over 8 years. Wonder if the fact that about 20 people have told us that a certain multiple winner of the Tour de France has trained on the training device in question might have any bearing on this finding. Of course, we have no proof. Wonder if the authors even asked him if there was anything he might have done to try to improve pedaling efficiency. I doubt it.

Anyhow. Enjoyed the thread. Suspect you continued to improve for at least 24 months at which time it started to "level out" some.

Frank

Oh FFS. This thread was dead and buried.

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