How hard is a 2 hour marathon in cycling terms

Joe Jackson wrote:

frankencrank wrote:

try this then. Determinants of metabolic cost during submaximal cycling

Lots to digest there, but in their conclusion the only time a lower pedal speed was a clear winner was at very low (50W) power outputs. At higher power outputs, they suggest a pedal speed of 1.4 m/s (perhaps inconveniently for you, equivalent to 80 rpms and 170mm cranks) is ideal.

The one, perhaps invalidating, sticking point I have with the study is that it was not done using actual cycling positioning. Rather, it sounds like they had the participants sitting upright. I understand their reasoning (trying to isolate the lower body) but in the real world, you can't ignore aerodynamics. Further, there was little to no discussion about the limb lengths of the participants. We do know they were all men so presumably they were 5'6" and above but they could have all been taller, or shorter, for all we know. That's a huge omission and makes me second guess everything.

frankencrank wrote:

Joe Jackson wrote:

Lots to digest there, but in their conclusion the only time a lower pedal speed was a clear winner was at very low (50W) power outputs. At higher power outputs, they suggest a pedal speed of 1.4 m/s (perhaps inconveniently for you, equivalent to 80 rpms and 170mm cranks) is ideal.

The one, perhaps invalidating, sticking point I have with the study is that it was not done using actual cycling positioning. Rather, it sounds like they had the participants sitting upright. I understand their reasoning (trying to isolate the lower body) but in the real world, you can't ignore aerodynamics. Further, there was little to no discussion about the limb lengths of the participants. We do know they were all men so presumably they were 5'6" and above but they could have all been taller, or shorter, for all we know. That's a huge omission and makes me second guess everything.

Science is never "inconvenient" for me. New data must simply be explained.

I am a little confused regarding your summary of their conclusion. From the study: "In summary, the present data indicate that mechanical power output and pedal speed, a marker for muscle shortening velocity, accounted for 99% of metabolic cost during submaximal cycling."

In my own data position does affect efficiency in that lowering the upper body lowers efficiency - my presumption is this is because muscle work that could go to driving the bike is diverted to using to push the recovery leg over the top. I would love to show that graph but I don't see any way to do this. My work was done at near the athletes racing power, about 20 watts below so fatigue didn't affect the data, allowing us to gather several data points a day. The affect of pedal speed on efficiency is independent of power (although the most efficient pedal speed will vary with power). The change in efficiency with pedal speed remains essentially unchanged, only the curve moves up or down.

Joe Jackson wrote:

frankencrank wrote:

Science is never "inconvenient" for me. New data must simply be explained.

I am a little confused regarding your summary of their conclusion. From the study: "In summary, the present data indicate that mechanical power output and pedal speed, a marker for muscle shortening velocity, accounted for 99% of metabolic cost during submaximal cycling."

In my own data position does affect efficiency in that lowering the upper body lowers efficiency - my presumption is this is because muscle work that could go to driving the bike is diverted to using to push the recovery leg over the top. I would love to show that graph but I don't see any way to do this. My work was done at near the athletes racing power, about 20 watts below so fatigue didn't affect the data, allowing us to gather several data points a day. The affect of pedal speed on efficiency is independent of power (although the most efficient pedal speed will vary with power). The change in efficiency with pedal speed remains essentially unchanged, only the curve moves up or down.

My comment was based on this statement: "For example, at a power output of 50 W, our subjects’ gross efficiency was greatest (16.7%) at the lowest pedal speed (0.61 m/s). As power output is increased, delta efficiency becomes increasingly deterministic of metabolic
cost. If our subjects were able to produce 400 W aerobically (e.g., elite cyclists), their gross efficiency would have been greatest, 23.5%, at a pedal speed of 1.4 m/s." See their chart for my conversion to crank length and cadence.

So low pedal speeds are great when you are tootling along but as power output increases, it becomes more efficient to utilize a higher pedal speed (right around what's standard in the industry). That extra efficiency should be put in context, though, and I address that next.

The bolded bit is a highly misleading statement when taken out of context. They state earlier in the Discussion portion that "Mechanical power output alone accounted for 95% of the variation in metabolic cost (Fig. 1), suggesting that, even with our wide range of pedaling rates, pedal speeds, and crank lengths, muscles’ ability to convert chemical energy to mechanical work was remarkably stable."

So pedal speed on its own plays a small role in the metabolic cost of cycling (on the order of ~4%). The also don't try to claim that pedaling rate has no discernible effect on metabolic cost, just that it's more closely related to pedal speed in their specific test (all sub-LT efforts).

You made some huge claims (10% power increase) as a result of a pedal speed change and this study has done nothing to change my mind about that being way off from reality.

Joe Jackson wrote:

frankencrank wrote:

Science is never "inconvenient" for me. New data must simply be explained.

I am a little confused regarding your summary of their conclusion. From the study: "In summary, the present data indicate that mechanical power output and pedal speed, a marker for muscle shortening velocity, accounted for 99% of metabolic cost during submaximal cycling."

In my own data position does affect efficiency in that lowering the upper body lowers efficiency - my presumption is this is because muscle work that could go to driving the bike is diverted to using to push the recovery leg over the top. I would love to show that graph but I don't see any way to do this. My work was done at near the athletes racing power, about 20 watts below so fatigue didn't affect the data, allowing us to gather several data points a day. The affect of pedal speed on efficiency is independent of power (although the most efficient pedal speed will vary with power). The change in efficiency with pedal speed remains essentially unchanged, only the curve moves up or down.

The bolded bit is a highly misleading statement when taken out of context. They state earlier in the Discussion portion that "Mechanical power output alone accounted for 95% of the variation in metabolic cost (Fig. 1), suggesting that, even with our wide range of pedaling rates, pedal speeds, and crank lengths, muscles’ ability to convert chemical energy to mechanical work was remarkably stable."

So pedal speed on its own plays a small role in the metabolic cost of cycling (on the order of ~4%). The also don't try to claim that pedaling rate has no discernible effect on metabolic cost, just that it's more closely related to pedal speed in their specific test (all sub-LT efforts).

You made some huge claims (10% power increase) as a result of a pedal speed change and this study has done nothing to change my mind about that being way off from reality.

frankencrank wrote:

Joe Jackson wrote:

My comment was based on this statement: "For example, at a power output of 50 W, our subjects’ gross efficiency was greatest (16.7%) at the lowest pedal speed (0.61 m/s). As power output is increased, delta efficiency becomes increasingly deterministic of metabolic
cost. If our subjects were able to produce 400 W aerobically (e.g., elite cyclists), their gross efficiency would have been greatest, 23.5%, at a pedal speed of 1.4 m/s." See their chart for my conversion to crank length and cadence.

So low pedal speeds are great when you are tootling along but as power output increases, it becomes more efficient to utilize a higher pedal speed (right around what's standard in the industry). That extra efficiency should be put in context, though, and I address that next.

The bolded bit is a highly misleading statement when taken out of context. They state earlier in the Discussion portion that "Mechanical power output alone accounted for 95% of the variation in metabolic cost (Fig. 1), suggesting that, even with our wide range of pedaling rates, pedal speeds, and crank lengths, muscles’ ability to convert chemical energy to mechanical work was remarkably stable."

So pedal speed on its own plays a small role in the metabolic cost of cycling (on the order of ~4%). The also don't try to claim that pedaling rate has no discernible effect on metabolic cost, just that it's more closely related to pedal speed in their specific test (all sub-LT efforts).

You made some huge claims (10% power increase) as a result of a pedal speed change and this study has done nothing to change my mind about that being way off from reality.

You misinterpret that data. The most efficient pedal speed depends upon the power. As the power increases the most efficient pedal speed (muscle contraction speed) also increases. The most efficient pedal speed at 400 watts was 1.4 m/sec. If a cyclist at 400 watts has a pedal speed of either 1.6 m/s or 1.2 m/sec we would expect gross efficiency to drop. To get a pedal speed of 1.4 m/sec using 175 mm cranks would require a cadence of about 75. Ullrich got it right, Armstrong got it wrong. Most pros are probably at a cadence of 90 or so (mimicking Armstrong because he won but for reasons other than his pedal speed), way higher than most efficient. Most amateurs (putting out 250-300 watts) are mimicking the pros so are way out of whack. My elite triathlete who raced at about 220 watts, was at about 1.7 m/sec before testing. When he slowed to 1.1 m/sec he gained 10% in power.

frankencrank wrote:

Joe Jackson wrote:

The bolded bit is a highly misleading statement when taken out of context. They state earlier in the Discussion portion that "Mechanical power output alone accounted for 95% of the variation in metabolic cost (Fig. 1), suggesting that, even with our wide range of pedaling rates, pedal speeds, and crank lengths, muscles’ ability to convert chemical energy to mechanical work was remarkably stable."

So pedal speed on its own plays a small role in the metabolic cost of cycling (on the order of ~4%). The also don't try to claim that pedaling rate has no discernible effect on metabolic cost, just that it's more closely related to pedal speed in their specific test (all sub-LT efforts).

You made some huge claims (10% power increase) as a result of a pedal speed change and this study has done nothing to change my mind about that being way off from reality.

Let me add a couple of more things. Yes, Power is the big variable but when it comes down to racing inches and seconds count. Why would a serious athlete avoid an easy 1, 2, 3, or even 10% increase in power just because it is "small".

Let me add, that it is the conclusion of the paper that cadence make no difference. In fact, in my athlete we saw that 10% increase even though we kept cadence pretty much constant. we did that by moving this 6'5" athlete from 200 mm cranks to 145 mm cranks.

Joe Jackson wrote:

frankencrank wrote:

You misinterpret that data. The most efficient pedal speed depends upon the power. As the power increases the most efficient pedal speed (muscle contraction speed) also increases. The most efficient pedal speed at 400 watts was 1.4 m/sec. If a cyclist at 400 watts has a pedal speed of either 1.6 m/s or 1.2 m/sec we would expect gross efficiency to drop. To get a pedal speed of 1.4 m/sec using 175 mm cranks would require a cadence of about 75. Ullrich got it right, Armstrong got it wrong. Most pros are probably at a cadence of 90 or so (mimicking Armstrong because he won but for reasons other than his pedal speed), way higher than most efficient. Most amateurs (putting out 250-300 watts) are mimicking the pros so are way out of whack. My elite triathlete who raced at about 220 watts, was at about 1.7 m/sec before testing. When he slowed to 1.1 m/sec he gained 10% in power.

We are saying the exact same thing:

Me: ...as power output increases, it becomes more efficient to utilize a higher pedal speed

You: The most efficient pedal speed depends upon the power. As the power increases the most efficient pedal speed (muscle contraction speed) also increases.

Armstrong was putting out more than 400 watts and given the multitude of variables associated with a given cyclist and their position on the bike it's a bit presumptuous of you to claim he was doing it wrong. Do you even know for certain what crank length he used on all his bikes? Do you know how efficiency is affected by pedal speed when one stands up on the pedals?

frankencrank wrote:

Joe Jackson wrote:

We are saying the exact same thing:

Me: ...as power output increases, it becomes more efficient to utilize a higher pedal speed

You: The most efficient pedal speed depends upon the power. As the power increases the most efficient pedal speed (muscle contraction speed) also increases.

Armstrong was putting out more than 400 watts and given the multitude of variables associated with a given cyclist and their position on the bike it's a bit presumptuous of you to claim he was doing it wrong. Do you even know for certain what crank length he used on all his bikes? Do you know how efficiency is affected by pedal speed when one stands up on the pedals?

We both agree that higher power will have a higher most efficient pedal speed. The question is: What is the most efficient pedal speed for any particular power.

While it may be presumptuous of me to say Armstrong was doing it wrong, in view of this study I think it presumptuous of anyone to say he was doing what was best. Unless one has done the work to determine what is best one is just guessing. But, we do have some data to suggest that for most people optimum pedal speed at 400 W will be about 1.4 m/s, at 200 W about 1.1 m/s, and at 50 W 0.61 m/s. One could easily interpolate the best pedal speed for their TT power and calculate what they are really are at and compare. I would be interested in if you could do that and see what you come up with.

While you think the study says the best improvement one could hope for would be 4% all I can say is we saw 10%. Perhaps that is because my "subject" was starting at a pedal speed way above 1.4 m/s and riding at a power well below 400 watts.