"Myth and Science in Cycling: Crank Length and Pedaling Technique" by James C. Martin PhD, NeuroMuscular Function Lab, The University of Utah
I am sooo excited about this particular topic. I've been riding for years and I've never been overly confident that I was riding the ideal crank length. After finding this article I am very comfortable with my 172.5mm cranks. Of course there's basically nothing wrong with the other standard crank length sizes either. Dr. Martin's data shows that "170 mm cranks would compromise the power of the shortest and tallest riders by AT MOST 0.5%. For example 6 watts out of 1200."
Another important point 120 rpm is close to optimal RPM (or cadence) when sprinting with standard production size cranks. I'm not suggesting that racers observe their cadence when riding, I just want to point out that higher cadences are generally NOT MORE EFFECTIVE. This will become even more apparent with a later point concerning larger gears being better than smaller ones for sprinting.
The summary of the above three charts is that 1. effect of crank length is small and significant only at extreme lengths, 2. 170mm cranks will compromise power of the tallest and shortest riders by at most 0.5%, 3. Pedal speed and pedaling rate interactively limit power, and 4th and most importantly: Cyclists can ride the crank length they prefer without concern of decreasing maximal power.
The next chart is a biggie.
The above chart shows that cyclists are more efficient pedaling at 60rpm cadence vs 100rpm cadence. This is big news from my point of view, and frankly I think it's a big big deal. So let me repeat the point....... lower cadences are more efficient than higher cadences, specifically 60rpm over 100rpm
UPDATE: February 5, 2012: The data from the above chart is correct, and has been supported by numerous studies. However, there is more to it and can be found in my article: "The Ideal Cadence for Competitive Cycling"
This is amazing stuff. I've been told countless times to get my cadence up. Generally 90 is often touted as the ideal cadence. It may still be for speed changes in criterium racing, but I think not for time-trialing. I tend to find myself falling into the upper 70s when time trialing despite trying to remind myself that 90 is better (turns out that it's not necessarily so). I plan on doing more riding with lower rpms and examine my watt data.
I know that a lot of cyclists will reject the notion that lower cadences are more efficient than higher cadences. I myself had some initial trouble with it. Generally I have found that my heart rate and wattage will stay fairly constant with different gear/rpm combination from the range of 70 to 90s I have noticed an heartrate upward drift as I go upward into the 90s.
The findings of this research are impressive (in my opinion). I contacted Dr. Nate Means (biology professor), Dr. Pam Hinton (exercise physiology), Dr. John Bowders (engineering) all to discuss this research document (powerpoint doc. actually) and try to understand/discuss the findings and implications. Nate has referred me to another scientist, Pam basically agrees with the Dr. Martin and John and I are going to chat more about it tonight while biking.
I was concerned to the point that I contacted Dr. Martin via email for clarification. He confirmed the facts as such: "The effect of pedaling rate on metabolic cost is pretty well established. Heart rate generally tracks well with met cost but its not the same thing. Also, there is individual variability in responses so you may be a bit different than the mean." (Cool Dr. Martin!)
And that's not all! Check out the next three blocks.
The summary findings are that the "rate of fatigue was greater when cycling with shorter cranks than longer cranks", and "fatigue per revolution was identical for the two crank lengths". And here's the biggie: "Data suggest that a relatively fixed increment of fatigue occurs with each maximal contraction".
In short, this means a bigger gear is better when doing longer sprints. If anyone has doubts just set up some sprint repeats with different gears and look at the data from your SRM or Powertap, etc. The bigger gear will win on the longer sprints. This is cool stuff my friends.
Summary: Common crank sizes are nearly all equal in efficiencies. Cranks size can be chosen for reasons such as ground clearance for cornering/obstacles (shorter), aerodynamics (shorter), or rehabilitation/flexibility (longer). Sprinting 120 rpm is best. 60 rpm is better than 100 rpm aerobically (generally lower cadences are more efficient than higher). Natural pedal stroke is best (do not pull up), crank length has no effect on fatigue, no effect on metabolic efficiencies and very small effect on maximum power. A big gear sprint is better than a small gear sprint (for 30seconds) .
To learn about the best video camera in the world for videoing cycling (which is the cameras that I use for my videos) click here.
I am sooo excited about this particular topic. I've been riding for years and I've never been overly confident that I was riding the ideal crank length. After finding this article I am very comfortable with my 172.5mm cranks. Of course there's basically nothing wrong with the other standard crank length sizes either. Dr. Martin's data shows that "170 mm cranks would compromise the power of the shortest and tallest riders by AT MOST 0.5%. For example 6 watts out of 1200."
Another important point 120 rpm is close to optimal RPM (or cadence) when sprinting with standard production size cranks. I'm not suggesting that racers observe their cadence when riding, I just want to point out that higher cadences are generally NOT MORE EFFECTIVE. This will become even more apparent with a later point concerning larger gears being better than smaller ones for sprinting.
The next chart is a biggie.
UPDATE: February 5, 2012: The data from the above chart is correct, and has been supported by numerous studies. However, there is more to it and can be found in my article: "The Ideal Cadence for Competitive Cycling"
This is amazing stuff. I've been told countless times to get my cadence up. Generally 90 is often touted as the ideal cadence. It may still be for speed changes in criterium racing, but I think not for time-trialing. I tend to find myself falling into the upper 70s when time trialing despite trying to remind myself that 90 is better (turns out that it's not necessarily so). I plan on doing more riding with lower rpms and examine my watt data.
I know that a lot of cyclists will reject the notion that lower cadences are more efficient than higher cadences. I myself had some initial trouble with it. Generally I have found that my heart rate and wattage will stay fairly constant with different gear/rpm combination from the range of 70 to 90s I have noticed an heartrate upward drift as I go upward into the 90s.
The findings of this research are impressive (in my opinion). I contacted Dr. Nate Means (biology professor), Dr. Pam Hinton (exercise physiology), Dr. John Bowders (engineering) all to discuss this research document (powerpoint doc. actually) and try to understand/discuss the findings and implications. Nate has referred me to another scientist, Pam basically agrees with the Dr. Martin and John and I are going to chat more about it tonight while biking.
I was concerned to the point that I contacted Dr. Martin via email for clarification. He confirmed the facts as such: "The effect of pedaling rate on metabolic cost is pretty well established. Heart rate generally tracks well with met cost but its not the same thing. Also, there is individual variability in responses so you may be a bit different than the mean." (Cool Dr. Martin!)
And that's not all! Check out the next three blocks.
The summary findings are that the "rate of fatigue was greater when cycling with shorter cranks than longer cranks", and "fatigue per revolution was identical for the two crank lengths". And here's the biggie: "Data suggest that a relatively fixed increment of fatigue occurs with each maximal contraction".
In short, this means a bigger gear is better when doing longer sprints. If anyone has doubts just set up some sprint repeats with different gears and look at the data from your SRM or Powertap, etc. The bigger gear will win on the longer sprints. This is cool stuff my friends.
Summary: Common crank sizes are nearly all equal in efficiencies. Cranks size can be chosen for reasons such as ground clearance for cornering/obstacles (shorter), aerodynamics (shorter), or rehabilitation/flexibility (longer). Sprinting 120 rpm is best. 60 rpm is better than 100 rpm aerobically (generally lower cadences are more efficient than higher). Natural pedal stroke is best (do not pull up), crank length has no effect on fatigue, no effect on metabolic efficiencies and very small effect on maximum power. A big gear sprint is better than a small gear sprint (for 30seconds) .
To learn about the best video camera in the world for videoing cycling (which is the cameras that I use for my videos) click here.
