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Old 09-16-2008, 03:04 PM   #1
Ole Jørgen Brønner
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Power output on erg. bike vs. concept2 machine

Does the watt-meter on erg. bikes in gyms usually show power transferred to the pedals, or some esitmation taking bio/mechanical loss into consideration?

I ask because I can pretty easily keep biking @ ~300W (at least for 30 min). This is about the same I average at for a 2k row (7 min) and after that I'm pretty worn out.

I assume rowing is less efficient than biking (moving a the whole body forth and back) but still..

I tried searching for the erg. brand, but couldn't find any definitive info.
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Old 09-16-2008, 04:23 PM   #2
Derek Franks
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Re: Power output on erg. bike vs. concept2 machine

I suspect that the bike at the gym is giving some kind of estimate. I also suspect it's giving you a number that is higher than your actual power output. My suspicion is based on the fact that if you were really able to output 300 watts for 30+ minutes fairly easily, then you're probably a professional cyclist.
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Old 09-16-2008, 10:32 PM   #3
Stephen R. Lampl
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Re: Power output on erg. bike vs. concept2 machine

It seems as though each cardio machine is different. I get a different reading when I program a stationary cycle for example, than I do setting an elliptical trainer made by the same company with the same exact settings...........Go figure.
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Old 09-17-2008, 09:53 AM   #4
Ole Jørgen Brønner
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Re: Power output on erg. bike vs. concept2 machine

Yes, I suspected it was too high. I actually asked the gym staff, and they said that it was _not_ a estimate, but I'm not even sure they understood the question.

Now, easily in 30 min was proabably not very accurate/what I meant. I most certain felt it at that point, but a good half went pretty smooth.

Just to be sure, the concept2 shows transferred power, right?
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Old 09-17-2008, 12:44 PM   #5
Phillip Garrison
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Re: Power output on erg. bike vs. concept2 machine

It's an estimate of power at the peddles based on more precise ergometer bikes. About 20% is lost at the wheel.
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Old 09-17-2008, 12:49 PM   #6
Mike Prevost
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Re: Power output on erg. bike vs. concept2 machine

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Originally Posted by Ole Jørgen Brønner View Post
Does the watt-meter on erg. bikes in gyms usually show power transferred to the pedals, or some esitmation taking bio/mechanical loss into consideration?

I ask because I can pretty easily keep biking @ ~300W (at least for 30 min). This is about the same I average at for a 2k row (7 min) and after that I'm pretty worn out.

I assume rowing is less efficient than biking (moving a the whole body forth and back) but still..

I tried searching for the erg. brand, but couldn't find any definitive info.
At 180 pounds I can hold 25 miles per hour on my road bike at 300 watts (assuming relatively flat terrain and mild wind). It is not professional cyclist territory for sure but it is a pretty decent power output. I can hold 300 watts for 30 minutes on my road bike but only 250 or so watts on the Concept II (just getting started) for 30 minutes.
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Old 09-17-2008, 12:51 PM   #7
Mike Prevost
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Re: Power output on erg. bike vs. concept2 machine

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Originally Posted by Mike Prevost View Post
At 180 pounds I can hold 25 miles per hour on my road bike at 300 watts (assuming relatively flat terrain and mild wind). It is not professional cyclist territory for sure but it is a pretty decent power output. I can hold 300 watts for 30 minutes on my road bike but only 250 or so watts on the Concept II (just getting started) for 30 minutes.
I should add that you would not expect power output to be the same for these activities because you are using different muscles.
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Old 09-17-2008, 01:06 PM   #8
Derek Franks
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Re: Power output on erg. bike vs. concept2 machine

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Originally Posted by Mike Prevost View Post
At 180 pounds I can hold 25 miles per hour on my road bike at 300 watts (assuming relatively flat terrain and mild wind). It is not professional cyclist territory for sure but it is a pretty decent power output. I can hold 300 watts for 30 minutes on my road bike but only 250 or so watts on the Concept II (just getting started) for 30 minutes.
MPH is irrelevant to this discussion. Power is power regardless of wind, terrain, etc, which is why it's the gold standard for training/racing output. How are you measuring watts on your road bike, BTW?

A Cat 1 cyclist should be able to output between 4.3-4.7 watts per kilo (350-380 watts in your case) for 20 minutes. If you can easily output 300 for 30 minutes, you can probably output 350 for 20 (if not more), which puts you right at what a Cat 1 cyclist is capable of.

For reference a Div 1 UCI pro should be able to output 5.5 watts per kilo for 20 minutes and a world class professional should be able to go over 6 watts per kilo for 20 minutes.
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Old 09-17-2008, 04:10 PM   #9
Mike Prevost
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Re: Power output on erg. bike vs. concept2 machine

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Originally Posted by Derek Franks View Post
MPH is irrelevant to this discussion. Power is power regardless of wind, terrain, etc, which is why it's the gold standard for training/racing output. How are you measuring watts on your road bike, BTW?

A Cat 1 cyclist should be able to output between 4.3-4.7 watts per kilo (350-380 watts in your case) for 20 minutes. If you can easily output 300 for 30 minutes, you can probably output 350 for 20 (if not more), which puts you right at what a Cat 1 cyclist is capable of.

For reference a Div 1 UCI pro should be able to output 5.5 watts per kilo for 30 minutes and a world class professional should be able to go over 6 watts per kilo for 20 minutes.
I was just putting the MPH info out there for a point of reference. A new cyclist without a power meter would likely have NO IDEA whether 300 watts is high or low......but they would probably recognize the effort required to go a particular speed.

350 watts is pretty good if you weigh less than 160 lbs. At my weight (180 lbs), it is more of a Cat 3 level.

Yes, measuring watts with a roadbike and Powertap. 300 watts for 20 minutes confirmed several times and 285 watts for an hour a couple of times. Probably got a bit higher than that this summer but did not test again before I pulled the plug on Ironman training.

Mike
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