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07/16/2012

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Dan

I've always found that lower effort naturally feels more comfortable at lower cadence. I don't think anybody can soft pedal at 100 rpm even without resistance.

Mike Hardy

Interestingly, there was a panel hosted by Quark (the power meter company) at Kona for 2011 and one of the things Hunter Allen mentioned was that the best marathons in IM come from 90+ rpm. But a quick scan shows e.g. Jordan Rapp doing 77rpm to win IM Texas. Have you noticed any correlation between higher rpm bike legs and faster marathons amongst athletes you've seen data for?

Michael

Joe some comments from me. Some points to be considered:

1. The course parcour will be different, which should result in a difference in cadence profile.


2. Is the Olympic race a road race or a TT? In a road race you can draft behind other riders in which case you can soft pedal at high RPM to get lactic out after steep climb for example.(for clarity the race may have been a TT but that wasn't clear from the post). In a TT a rider will ride at the limit.

Joe Friel

Michael-- You're right but I've seen this in the cadence distribution charts of every pro's data I have ever seen for non-drafting races, which is what these were.

Joe Friel

Mike H-- I've seen just the opposite of what you report here. But tell you what, I'll do a search of the research on this and see what it tells us. Then come back to the topic here.

Martin

"The longer the steady-state race is, the more economical it must be to pedal at a slower cadence."

I'm not sure you can make this inference from the data. It may just be the athlete lost concentration. You'd need to get the athlete to do some IMs with specific goal of keeping cadence high in order to come up with some firmer conclusions.

Joe Friel

Martin--Again, it's not just this one athlete I see this in. It's _all_ experienced triathletes. And I don't know why. That's just a guess.

Bob

Over the course of several years I have found that on essentially flat roads at a fairly stable speed of 18 mph judging by RPE and HR that I am most efficient at about 75-77 rpm. This is not true for moderate sustained climbs where even allowing for a slower pace I am more comfortable around 85 rpm. I don't seem to have a comfortable pace/cadence for steep climbs. I assume that my climbing issues are due to inadequate power/leg strength.

Harry

Joe - If you divide average speed (power?) by average cadence (velocity?)the force applied is similar for both races. Is this true or indeed relevant? Should we be looking at applying an optimum force rather than an optimum cadence?

Joe Friel

Harry--Interesting. I haven't check it out but I'd think the average torque (rotational force) would be higher for the shorter race along with a slightly higher cadence. This would account for the higher power over 40k as opposed to 112 miles.

TriDot

Nice chart and observation on cadence and race distance. Higher cadence is definitely more effective. But the energy costs are greater...there's a higher energy cost simply in moving your leg mass at higher cadence for longer even before you consider the force applied to the pedal. I believe that the athlete's leg mass and limb length play a factor here when comparing one athletes optimal cadence to another.

Ashley

Joe, from findings I have read and can not remember where the sorse was from, but I remember it be viable. Is it correct to say the lower cadence on the longer events will translate into a more efficient run? I remember the reasons why but this comment would be to huge.

Joe Friel

Ashley--I've got one study on that topic in my files. It found that pedaling 20% faster than normal resulted in a 1-minute faster 322m run off the bike compared with normal and 20% slower cadence. But I've found that with elite triathletes as the distance of the race increases they pedal with a slower cadence. Although last Saturday Pete Jacobs won in Kona with an average cadence of 90--relatively fast for the IM pros.

matt schiff

I agree with Harry that for long distances the force or torque at the same rpm's is much less than for shorter events and just a small percentage of a riders maximum. When producing a low torque the expense of fast leg movement becomes higher. For any rider an efficiency curve could be drawn starting with 1 watt of power certainly being produced by the slowest movement of say 10 rpms, with both torque and rpm increasing (but at different rates for different riders) up to the point where spinning a higher gear results in a huge additional expense of energy (again rider dependent rpms).

Dan Whiley

Interesting topic (although I was searching for something different about cadence!), but here's my hypothesis:

The general view I've picked up is that some studies (sorry Joe, I don't have the references to hand) indicate that the most metabolic efficient cadences are in the 50-60rpm range. However, this doesn't account for muscular endurance, and the higher force required to generate a given power at lower cadence leads to earlier fatigue for the athlete.

Now, for an IM distance, the athlete will be operating at a lower power than for the Olympic distance, given the much longer distances/times. So would it make sense to assume that muscular fatigue is less of a concern for these lower levels and hence you are looking for the most efficient cadence (i.e. lower). For the shorter distances where operating at/above LT, muscular fatigue is a larger concern, so a higher cadence is employed to "transfer" more of the effort onto the cardiovascular system?

Take this to the extreme and look at the very high cadences the track cyclists use. But then again, they can't afford gears or brakes for their bikes.

As I said, just a hypothesis...

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