Now, with a straight face, you can tell your partner, "shorter is better" and mean it.

Discussion in 'Cycling Training' started by Fday, Sep 23, 2010.

  1. Fday

    Fday New Member

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  2. kopride

    kopride Member

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    Interesting, but I am in the "if it is so obvious from a 2001 study, then someone in the tour would have already done it camp." Teams have been playing with aero positions in wind tunnels for years, but nobody thought to shorten cranks yet? Again, I am very skeptical of this video argument from that perspective:
     
    No. 1: You have no wind tunnel studies to back up your aero arguments
     
    No. 2: You do not appear to have any recent power studies using trained cyclists to back up your power argument
     
    No. 3: There are times in cycling when you stand, i.e. climbing and sprinting.
     
    I mean, these are the obvious ones, but the burden is on the proponent to do a peer reviewed study, if you are going to make scientific claims. IOW, select a statistically significant sample or time trialists, rent a wind tunnel and prove your contention. Next, get a sample of experienced cyclists and adjust cranks over a course that includes standing and sitting with power meter equipped bikes, and prove your theory. Other than that, you seem to be presenting an unproven theory as scientific fact, which is fairly misleading. It almost smacks of the creationists who use cartoons and diagrams to prove the "science" of intelligent design. If you can prove it, then you are certainly changing conventional thought.
     
    spacebar likes this.
  3. Fday

    Fday New Member

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    Well, the Martin study was a peer reviewed study. He is a well-known and well-respected researcher in this area. I am simply making inferences from that study and my own experience experimenting with this. I am simply making the argument based upon this study and what is commonly accepted as true. There certainly is no evidence to prove that what I say is wrong.
     
    Regarding the "why haven't the pros adopted this yet" argument. I am aware of at least two elite pros who were given this recommendation, Levi Leipheimer and Chris Lieto, yet they were uncomfortable with such a radical change. Levi shortened his cranks a little bit and I don't think Chris did anything, based upon what I read. It is very difficult for someone at the very top to make big changes because they are at the top and probably think they are there because the choices they have made are the right ones for them. I think it will take someone who is a little lower on the totem pole to "take the risk", hoping to see the benefit and leapfrog the competition. Perhaps my essay will stimulate some to experiment with this.
     
  4. kopride

    kopride Member

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    Ok, is this the same Martin Study that has a population size of 16 and concluded:
     
    "These data suggest that pedal speed (which constrains muscle shortening velocity) and pedaling rate (which affects muscle excitation state) exert distinct effects that influence muscular power during cycling. Even though maximum cycling power was significantly affected by crank length, use of the standard 170-mm length cranks should not substantially compromise maximum power in most adults."
     
    And you apparently ignore a later Martin study where he concludes:
     
    Determinants of metabolic cost during submaximal cycling. McDaniel J; Durstine J L; Hand G A; Martin J C Department of Exercise Science, University of South Carolina, Columbia, South Carolina 29208, USA JOURNAL OF APPLIED PHYSIOLOGY (2002 Sep), 93(3), 823-8.

    The metabolic cost of producing submaximal cycling power has been reported to vary with pedaling rate. Pedaling rate, however, governs two physiological phenomena known to influence metabolic cost and efficiency: muscle shortening velocity and the frequency of muscle activation and relaxation. The purpose of this investigation was to determine the relative influence of those two phenomena on metabolic cost during submaximal cycling. Nine trained male cyclists performed submaximal cycling at power outputs intended to elicit 30, 60, and 90% of their individual lactate threshold at four pedaling rates (40, 60, 80, 100 rpm) with three different crank lengths (145, 170, and 195 mm). The combination of four pedaling rates and three crank lengths produced 12 pedal speeds ranging from 0.61 to 2.04 m/s. Metabolic cost was determined by indirect calorimetery, and power output and pedaling rate were recorded. A stepwise multiple linear regression procedure selected mechanical power output, pedal speed, and pedal speed squared as the main determinants of metabolic cost (R(2) = 0.99 +/- 0.01). Neither pedaling rate nor crank length significantly contributed to the regression model. The cost of unloaded cycling and delta efficiency were 150 metabolic watts and 24.7%, respectively, when data from all crank lengths and pedal speeds were included in a regression. Those values increased with increasing pedal speed and ranged from a low of 73 +/- 7 metabolic watts and 22.1 +/- 0.3% (145-mm cranks, 40 rpm) to a high of 297 +/- 23 metabolic watts and 26.6 +/- 0.7% (195-mm cranks, 100 rpm). These results suggest that mechanical power output and pedal speed, a marker for muscle shortening velocity, are the main determinants of metabolic cost during submaximal cycling, whereas pedaling rate (i.e., activation-relaxation rate) does not significantly contribute to metabolic cost.
     
    Here is a more recent Martin power point where he again notes that there is no real disadvantage to a 170mm crank for almost any trained cyclist:
     
    http://www.plan2peak.com/files/32_article_JMartinCrankLengthPedalingTechnique.pdf
     
    Again, I am very skeptical of your "elite guys at the top" won't change argument. The guys at the top have spend hours in wind tunnels looking for free speed. Shortening cranks by 2.5 cm is nothing earth shattering if it meant real speed increases.
     
    In addition to what appears to be very selective citation of small studies, adding to my skepticism is the fact that you are really trying to sell a product. . which is your power crank gizmo.
     
     
     
  5. Fday

    Fday New Member

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    I am not ignoring anything. Martin says use of 170 cranks will not SUBSTANTIALLY affect power. Looking at his data it looks like the 170 length gives about a 1% power difference. That would be 2-3 watts at what most here are racing at.
     
    My argument with him is this.
     
    1. Why would an athlete want to give up any power when nothing need be done to claim the extra power but change the cranks on the bike?
     
    My second argument goes to the aerodynamic position. Martin did not test in the aerodynamic position. I infer an mechanism to explain his findings that would suggest this difference becomes much larger when in the aerodynamic position.
     
    If you want to give up 2-3 watts for the kind of racing you do I guess that is your choice. But, for those doing TT type racing I would guess the difference is more on the order of 5-10 watts and you would be giving up substantial aerodynamic benefits also. Even if there is no power advantage, there are clearly substantial aerodynamic advantages to shorter cranks. Why anyone would willingly give these up when the "fix" is so simple is beyond me but I fully expect lots to come here and argue it is not necessary to change. You are simply the first.
     
    The point is there is a theoretical advantage to making this change and people should not be afraid to experiment to see if it works for them.
     
     
  6. kopride

    kopride Member

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    Well, the second study demonstrates that pedal length doesn't even factor in the regression at all, it's not even statistically significant. Listen, among 16 cyclists, which was the sample size of the study you cited, I could probably show you that there is a 2-3 or 5-10 watt difference between the riders that gave or received oral sex the night before in my cycling group. I'm just not convinced that you can prove anything from such a minor difference in an isolated study. And the first study was max power, not steady state or endurance power over a 40k tt. You want to test your crank length theory and gizmo on multiple studies of sample sizes approaching 1000, then maybe I will be more impressed, but for now, you are presenting very misleading data in support of your theory. The study did not prove, and was not intended to prove, that under every circumstances, with every rider, shorter is better. It simply explored whether there was support for the idea that cranks longer than 170 could produce more power.
     
    Next, you say that there are clearly substantial aero advantages. . . based upon what, your inference. Again, elite riders spend hours in wind tunnels exploring position and other issues. Do your study with a nice sample size and publish your results. Until then, don't present your own theory as fact, i.e. there are clearly aero advantages to shorter cranks.
     
    Actually, your point isn't that people are afraid to experiment. They do. Riders are in wind tunnels and on ergs all the time experimenting and perfecting fit and position. Your point is that people should invest money and buy your gizmo on faith in the hopes that experimenting will improve their riding. Everybody that bought biopace chain rings in the 80s did a similar experiment. It's the manufacturer or proponent's job to prove the science of their product if they want to make scientific claims--not the consumer's job to disprove or experiment.
     
     
  7. Fday

    Fday New Member

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    Don't dwell on the 16 cyclists number. His data achieved statistical significance.
     
    Your problem, as I see it, is you are focused on the power issue alone. If we were simply arguing power I wouldn't have much to stand on, even though I believe the data would be much more convincing if the study were to be repeated with the riders in the TT position (or comparing the two positions). As I said, even if the power didn't change at all, which you argue, it doesn't matter to my argument because the aerodynamics will change. And for TT type efforts that is a big deal, in case you haven't figured that out yet. There are well established principles regarding aerodynamic drag. I mention them an show how shorter cranks allow the rider to present a smaller frontal area. All else being equal a smaller frontal area will have less drag resistance than a larger frontal area. If you don't care about that type of racing feel free to ignore this. But, if you want to address the point of the video you have to counter my point about the aerodynamics also.
     
  8. kopride

    kopride Member

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    Well, first of all, you don't cite the study for a TT pace which is the second Martin study concerning sub maximal efforts, and which found that pedal cranks did not even contribute to the regression model. . in other words, pedal cranks were not statistically significant in submaximal, i.e. time trial pace. . instead, you cite the 16 person study for max power, which is completely irrelevant to a TT. And which in no way concludes that cranks shorter than 170 mm are better than 170 mm cranks for even max power.
     
    Second, shortening the cranks increases seat height and also affects aero positioning in lots of subtle ways. That may or may not make a rider slippery. I'm not saying that an individual rider who experiments in a wind tunnel might not find that shorter cranks are better for his set up. It's possible. . . for that rider. But your inferences about shorter cranks may not pass scientific scrutiny. And my guess is that if they did, we would see TT riders racing on 140 mm cranks, or at least 165 as standard.
     
    My point is that you are making conclusions about power and crank length that Martin was not willing to make; and are proposing an aero theory that is completely untested; and in fact, the existence and prevalence of wind tunnel testing suggests either that your broad conclusions are not true; or aero experts assisting these elite riders are idiots and refusing to adopt a very easy beneficial change.
     
  9. Fday

    Fday New Member

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    I certainly am drawing conclusions and making inferences that Martin was not willing to make because I am trying to put incomplete data together to improve outcome and Martin was writing a scientific paper and such inferences are inappropriate for such papers. I suspect that Martin's TT effort data didn't show differences because we would expect the absolute differences to be even smaller at that lower power level. His max power study didn't even show statistical significance between 170 and 145. What I am looking at is the trend line (and the spread for each length, which was very consistent) and concluded that with a larger group the difference between 145 and 170 probably would have eventually reached statistical significance with enough people. If he had done that I suspect his conclusion would have been quite different. It would take a very large cohort to show the same at lower power levels. Sometimes it is important in interpreting scientific papers to understand what was not done and what the inferences of the data might mean if the study was done differently.
     
    I may not be correct but I think I make a pretty convincing argument. I have made my case and I think it is a very good case. Feel free to ignore it if you wish.
     
  10. kopride

    kopride Member

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    Well, Martin was not willing to make them because the study didn't support the conclusions you want to draw. He was doing an academic study and you are trying to promote your product. If you want to promote your product with science, then hire a researcher like Martin and have him test your theory. Don't use academic papers like a Chinese menu and pick and choose portions to promote a product, and ignore or discount findings which do not support your theory, or offer a theory as to why the other more relevant studies do not support your theory, which is what you did to "make a convincing argument."
     
    I am not persuaded by your argument because I don't think you've tested your hypothesis, nor do I think that there is a real fit between the academic studies you contend support your theory, and your conclusions. I will agree that it appears as though you've convinced yourself and think you have a good case. Personally, I would not buy a product that is marketed with alleged "scientific proof," when the theory remains unproven. From my perspective, it is misleading. If you want to send me a pair of free gizmos to test for you according to designated protocols, or are asking me to participate in a research trial, well then, I probably would not ignore that type of request. If you are asking me whether I want to pay good money for a product that is based upon your inferences, I'm more skeptical.
     
    Good luck, and it is an interesting discussion in any event.
     
     
  11. Fday

    Fday New Member

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    Hey, the argument I am making applies to everyone whether they have or don't have my product. I simply believe this is a big enough deal for those who do time-trial events (pretty much every triathlete) that I have incorporated the ability to experiment with this idea into my product.
     
    Some people are early adopters and some aren't. You clearly are not.
     
     
     
  12. frenchyge

    frenchyge New Member

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    I'm with Frank on this one, ie, even if the effect of receiving oral sex before a competition cannot be statistically proven to exist, a rider would be crazy to ignore the advantage, however small, that it could provide. I'm going to try to incorporate this into my competition regimen effective immediately.
     
     
  13. frenchyge

    frenchyge New Member

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    Frank, did I miss where the sustained, submaximal testing results showed a difference related to crank length?
     
    The study you referenced was for maximal power testing, was it not?
     
  14. fergie

    fergie Member

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    Your not supposed to have noticed that!
     
    Frank, quick put some more bells, whistles, special effects and better music into your next spamformercial, people are watching and still paying attention to the details!!!
     
  15. swampy1970

    swampy1970 Well-Known Member

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    Shortening cranks would have other 'fun' implications. Just imagine all the extra cornering clearance you'd get... that'd be worth it if you were a crit guy or just fancied putting guys through hell on a technical road course. You lower the weight of the cyclist and you get other 'cornering' benefits too. Less weight too - if you're a weight weenie - shorter cranks, shorter seat tubes, less frame material... all dependant to what extremes you take it too.
     
    The aero theory was tested - and why you don't think that someone hasn't tested it is beyond me... but you seem to have come to a lot of conclusions without (a) a long history in cycling and (b) you just seem to want to argue with Frank because you feel like writing long replies that are 'seemingly' better put together than your posts of old. The aero-short crank theory was tested by the US Olympic team back in the 90s just in case you were wondering. I don't think that much came from it other than the riders were much more aero but didn't like the cranks. It was during the demise of "Cycling Science" magazine and the awkward period of web evolution (aka the mid 90s) so I lost track of what was going on with regards to that one.
     
    There have been quite a few tests and studies that basically say that there's no huge difference between shortish cranks and longish cranks. I don't think that anyone has ever said that, or has been able to prove, that there's a 'formula' for correct crank length even for something as simple as basing that of leg length. Just theories and opinions and God knows that there's more than a few opinions in cycling.
     
    But since you have an opinion on the subject, why do you think that 170mm should be some kind of magic number treated with some special reverence? It's not like there was a study done to come up with that length it was used because... well, someone liked it.
     
    As for me - well, I used to love time trialing on 185mm TA's... but I tried bazzing around on 165mm's the other week in a big gear and that was fine too. Didn't try anything else because I was pressed for time but oddly, I didn't find myself wanting to pedal a smaller gear, faster. I felt the same which I guess is what's to be expected if you actually think about it. 1cm is hardly a huge difference - which when you think about the "fear of God" some cyclists get from making such a small positional change makes the whole thing quite amusingly silly. "Oh my God... I was told to move my seat 4mm... the world will end, the skies will fall and life as we know it will come to an end." Quite.
     
    If you wanted more leverage to remove your lug nuts on the car, would you think adding 3cm to your 50cm tool would add a significant benefit? No... neither would I. You'd go for something at least twice the length and get some real force behind it and swing of the darned thing. Maybe I should test 220mm cranks for climbing hills... or even try 100mm cranks for time trialing on. Ah, the fun I can have with adjustable cranks and a power meter and too much time.
     
     
  16. Fday

    Fday New Member

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    Yes, one has to infer that they are related. One has to draw certain inferences to get to where I went. None of the inferences are unreasonable.
     
    BTW, found an article out of triathlete magazine that went to this issue. While I disagree with some of their conclusions and statements they did say this, that goes to the "are shorter cranks more aero issue", which I was able to infer without wind-tunnel data. (Isn't it just amazing how sometimes inferences can lead one to the right conclusion?)
    [​IMG]
    BTW, I believe the author should have written that the seat would be higher with shorter cranks, not lower. 30% reduction in wind drag. Hey, almost 40%. :)
     
  17. swampy1970

    swampy1970 Well-Known Member

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    One should not place to much specificity on this. I'm a firm believe that one should incorporate the doggy style position in order to simultaneously achieve pleasure and stretch the psoas.

     
     
  18. swampy1970

    swampy1970 Well-Known Member

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    You could always get Zinn to build you some cranks... and there's a few companies that will shorten various models of cranks too. It's not like you HAVE to buy PowerCranks to try this stuff.
     
     
  19. GetSetGoSports

    GetSetGoSports New Member

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    There was some research done - and I am too tired to find it - but basically it said that the longer, more powerful, and faster the range of motion that a muscle has to contract, the more oxygen, glycogen, fuel, etc. it requires to travel the range.
     
    So, longer cranks require a larger range of motion by definition, and so to fuel that range of motion at equal speed and power as shorter cranks the legs will require more fuel. In exchange for more fuel required, you gain leverage. There are also some dynamics in regards to the speed of the foot travel that i can't wrap my brain around right now.
     
    I think that the balance will play out somewhere on balance between the bodies ability to deliver fuel to the muscle (VO2 is the normal limiter in a well trained athlete), compared to the leverage achievable at the maximum delivery rate.
     
    Once the fuel delivery is maxed out, the gain in leverage is more than offset by the loss of either speed or producible power.
     
    Someone please fill in the blanks on this one.
     
     
  20. tessitori

    tessitori New Member

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    Very interesting. I just saw Max Testa yesterday at Interbike and asked him what his general thoughts were on shorter cranks and his answer is that more people should be riding cranks as short as 155 because there is actually no decrease in power and an increase in efficiency.
     
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