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2009-04-16 1:15 PM
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Subject: RE: Cycling power: how many watts does an average person pull?
so what do you guys think of back-calculating from calorie burn?  Of course it's a dirty estimate, since you have to assume the cal total is correct, then you have to estimate your efficiency on the bike (usually between 20-25%).  for my spin last night that would put me at 172 (at 20% efficiency) average.  Sounds pretty close to what it should be based on my weight and experience level. 


2009-04-16 1:25 PM
in reply to: #2088946

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Subject: RE: Cycling power: how many watts does an average person pull?
Daremo - 2009-04-16 12:43 PM I personally think the ibike is crap based on what I've heard/read and the way it takes measurements.  But that is just my opinion on it as I have never actually used it.  The premise behind it doesn't make sense for me (accelerometer).


As someone who just bought an iBIke (used Gen II model), I think they've come along way from the original model.  it's not to say they don't have their downsides, but as a less expensive alternative, they make a lot of sense.  And anyone buying the new Gen III models is going to get very accurate results in comparison to a PT or Quarq Cinqo.  This link is to a ride analysis.

http://www.ibikesports.com/documents/Johnson_ride_analysis.pdf
2009-04-16 1:26 PM
in reply to: #2089224

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Subject: RE: Cycling power: how many watts does an average person pull?
Bioteknik - 2009-04-16 2:15 PM so what do you guys think of back-calculating from calorie burn?  Of course it's a dirty estimate, since you have to assume the cal total is correct, then you have to estimate your efficiency on the bike (usually between 20-25%).  for my spin last night that would put me at 172 (at 20% efficiency) average.  Sounds pretty close to what it should be based on my weight and experience level. 


Sounds little better than a random guess. 

I'm not sure why people care much about this unless you have the ability to use it to train & race.  I don't go and compare my watts with other people.  I compare my race results.
2009-04-16 1:32 PM
in reply to: #2087975

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Subject: RE: Cycling power: how many watts does an average person pull?

dgunthert - 2009-04-16 1:17 AM
JorgeM - 2009-04-15 10:01 PM true and part of the reason is because indoor trainer's flywheel are usually small and not heavy enough to provide that inertia to generate the same rolling resistance that we experience when riding outdoors hence it is usually a bit harder to produce the same power indoors or to put it in another way; it is usually easier to produce a bit more power riding outdoors. Some trainers are now offering their models with bigger flywheels and even selling extra weight, OTOH systems like the computrainer that regulates the tension tend to replicate a bit closer the feel for outdoors riding.

If your power is 'x' indoors, in general it will be a bit higher outdoors
If you're talking only about trainer-based power systems like the CT, I could see this. The wording of your response makes it seem more general for all power meters, though, and I can't see how that could be true. My PT is measuring the power at the rear hub. Any interaction between systems 'downstream' from it (tire/drum, drum/flywheel, etc) aren't going to affect that measurement in the least. Likewise, if I was using a BB-based system like an SRM, the efficiency of the drivetrain would have no impact on my power measurement. My chain could be clean as a whistle or covered with crap, it wouldn't have any impact on the power I'm applying to the pedals. Sure, it would impact the power getting to the hub and therefore the wheel, but that's of no concern when I'm training as long as my legs are doing the work I need them to do.

Newtons first law:  Objects in motion will remain in motion until an outside force acts upon it.  When you are riding outside the only forces that act in opposition to your forward motion is wind resistance and friction with the ground.  However, when you are on the trainer, a different set of forces are at play resulting in little inertia (the tendency to remain in motion) in the system.  This lack of inertia requires additional force to overcome which will make your ride a lot more difficult.  Additionally, more force must be applied to overcome the "dead spots" (changes in direction of your pedal stroke) in order to maintain your target wattage. 

How's that for physics?



Edited by triOK 2009-04-16 1:33 PM
2009-04-16 1:38 PM
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Subject: RE: Cycling power: how many watts does an average person pull?
JohnnyKay - 2009-04-16 2:26 PM
Bioteknik - 2009-04-16 2:15 PM so what do you guys think of back-calculating from calorie burn?  Of course it's a dirty estimate, since you have to assume the cal total is correct, then you have to estimate your efficiency on the bike (usually between 20-25%).  for my spin last night that would put me at 172 (at 20% efficiency) average.  Sounds pretty close to what it should be based on my weight and experience level. 


Sounds little better than a random guess. 

I'm not sure why people care much about this unless you have the ability to use it to train & race.  I don't go and compare my watts with other people.  I compare my race results.


maybe, I had seen an article comparing polar readings to those of a power meter and they jived.. but as you were saying I only did it for the hell of it and I know I need to be getting my bike time in. 
2009-04-16 2:14 PM
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Subject: RE: Cycling power: how many watts does an average person pull?
So one thing I don't get is with an iBike you're measuring wind and speed (and some other stuff I assume). As far as wind goes, how does the unit distinguish between apparent wind (the wind you create by just moving forward) and true wind or the direction of wind (tail wind vs. headwind)? Or does it not matter.


2009-04-16 3:44 PM
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Subject: RE: Cycling power: how many watts does an average person pull?
I'm still trying to figure out how to convery lbs to kgs!!
2009-04-16 4:07 PM
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Subject: RE: Cycling power: how many watts does an average person pull?
merlin2375 - 2009-04-16 3:14 PM So one thing I don't get is with an iBike you're measuring wind and speed (and some other stuff I assume). As far as wind goes, how does the unit distinguish between apparent wind (the wind you create by just moving forward) and true wind or the direction of wind (tail wind vs. headwind)? Or does it not matter.


I can't pretend to understand the science of it - but it's quite accurate.  In the software it can display the wind vs wheel, or ground speed wind (which when compared to some meterological websites for the ride times show it's very close).  The wind vs wheel is very cool, because it shows specifically when you have the wind acting against or with you.  So within the software you can see your watts, the wind you're riding against, the slope of the hill at that time, etc.  It gives you additional data rather than just saying you were pushing 200 watts at mile 20.  You can see what external factors were helping or hindering you at that point. 
2009-04-17 8:00 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
newbz - 2009-04-15 10:13 PM Jorge, this is purely an educated guess, but my thoughts on the diff in the FTP vs 20 min power would be: 1) this is probably the largest one for me, i come from a rowing background and am very used to putting out near max effort for 6-25 min. so a 20 min test is nothing new at all for me 2) i dont have a lot of longer training under my belt 3) for me doing longer tests mentally is not something i am great at right now. i have no idea on 5 min power
Thanks! Considering Olympic distances are your focus, having a solid 60 min power (aka as FTP) is key for you as this intensity is specific for your races and correlates with Maximum Lactate Steady State which among other things is an excellent tool to evaluate fitness level, to predict performance and to design plans around. (Actually a strong 60 min power it is really important for all triathletes from sprint to IM)

Anyway, you might want to get on a threshold power diet for 6-8 weeks and work to get your 20 min power closer to your 60 min power; that is within 3-5% so you can flatten your power curve and be as strong as your potential indicates you should.

Some ideas would be doing short sets 5-10' @ 105-110% of FTP, longish sets 15-20' @ 100-105% of FTP (both with short rests in between 1-3' @ 60-65% of FTP) or do some tempo rides 1-2 hrs @ 80-85% of FTP with the last 20' @ 95-100% of FTP. Just a suggestion
2009-04-17 8:11 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
I forgot to include on my last post; you should also track your VO2 max (which closely relates to your 5 in power) as that will let you know your max aerobic capacity power. That sets the tone as to how high your power threshold could be with proper training. Here is a nice article by Philip Skiba using a house analogy as to why knowing  and training your VO2max and FT power are important.
2009-04-17 9:11 AM
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Subject: RE: Cycling power: how many watts does an average person pull?

JorgeM - 2009-04-15 1:58 PM How much power a person can generate depends on many things such as fitness, genetics (height, weight), gender, age, bike fit, power meter, etc. The only way to compare how closer or not you are vs another rider is by comparing your power to weight ratio. That is taking your best average power for a given duration (i.e. 60 min) and divided by your weight in Kilograms. That way you can compare how much power you generate per Kg and how much power I for instance can generate x Kg.

To give you an idea, currently my 60 min power (estimated using Monod's critical power model) is around 256watts, and I weight 140 pounds, that puts me @ 4.03- w/Kg.

Once you figure out your power for 'x' duarion and get your w/Kg ratio you could use the attached table on the link to see how do you stack the power #s produced by some of the best cyclists at each durationm although the power readings you might get on those machines might not be accurate:

http://home.trainingpeaks.com/media/69406/powerprofiling_v4.xls  


How come bike weight is not included when calculating w/kg ? I would think it shoud?



2009-04-17 9:26 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
slake707 - 2009-04-17 9:11 AM
How come bike weight is not included when calculating w/kg ? I would think it shoud?



If money isn't an issue, wouldn't the majority of people ride the mandatory minimum weight bike, or close to it?

Yes, us with the less expensive equipment are producing more power to go the same speed as you weight weenies! So one day, when I get my superultramegasweet bike I'll be that much faster from doing all the extra work =)
2009-04-17 9:51 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
triOK - 2009-04-16 1:32 PM

Newtons first law:  Objects in motion will remain in motion until an outside force acts upon it.  When you are riding outside the only forces that act in opposition to your forward motion is wind resistance and friction with the ground.  However, when you are on the trainer, a different set of forces are at play resulting in little inertia (the tendency to remain in motion) in the system.  This lack of inertia requires additional force to overcome which will make your ride a lot more difficult.  Additionally, more force must be applied to overcome the "dead spots" (changes in direction of your pedal stroke) in order to maintain your target wattage. 

How's that for physics?



Well, the first couple of sentences are certainly true. However, as soon you start talking about "additional force" it falls apart. Wattage is a direct, objective measure of force. So applying additional force is, by defininition, applying additional wattage.

Personally, I think there are 2 factors at work. One is simply the static nature of the position on a trainer. Your body is limited in its range of movement compared to on the road. The other factor is a result of the consistency required in maintaining a constant effort on the trainer. This is where the flywheel comes in. On the road, you may vary between 190 watts and 210 or more in very short time frames even on a very flat section of road where you think you're holding steady wattage of 200. On the trainer, you have to hold that cadence and wattage even more steadily. There's definitely a different feel to riding for an hour or so at right at 200 and riding for an hour while varying between 170 and 230. With a bigger flywheel, you don't have to hold it quite so exactly, just like on the road.
2009-04-17 10:30 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
slake707 - 2009-04-17 9:11 AM

JorgeM - 2009-04-15 1:58 PM How much power a person can generate depends on many things such as fitness, genetics (height, weight), gender, age, bike fit, power meter, etc. The only way to compare how closer or not you are vs another rider is by comparing your power to weight ratio. That is taking your best average power for a given duration (i.e. 60 min) and divided by your weight in Kilograms. That way you can compare how much power you generate per Kg and how much power I for instance can generate x Kg.

To give you an idea, currently my 60 min power (estimated using Monod's critical power model) is around 256watts, and I weight 140 pounds, that puts me @ 4.03- w/Kg.

Once you figure out your power for 'x' duarion and get your w/Kg ratio you could use the attached table on the link to see how do you stack the power #s produced by some of the best cyclists at each durationm although the power readings you might get on those machines might not be accurate:

http://home.trainingpeaks.com/media/69406/powerprofiling_v4.xls  


How come bike weight is not included when calculating w/kg ? I would think it shoud?

 For pure comparison between two rides is not that important unless you are testing on a climb and/or one rider is using a significantly heavier bike than the other one. It could also depend whether you weight yourself in the AM, PM, before or after the test and power fluctuates a bit from day to day based on your chronic fatigue, fueling, etc. What you seek with the w/Kg is more of a baseline for you to track your fitness gains and compare yourself to others in general. Still, at the end of the day training by power is just a way to make training more efficent by targeting specific adaptations, track fitness gains and total load but they don't give prices for the highest w/Kg ratio, they do for the guy who crosses the finish line 1st.

Anyway, sure you can calculate it considering the weight of your bike to get a more precise w/Kg if you want to get picky about it or are planning to race up alpe d'huez and every single fraction of w/Kg is important. What matters IMO is that however you calculate your w/Kg is repeatable, that'll be more useful for you (i.e. weight yourself at the same time, test on the same venue, under similar conditions, rested, etc.)

FYI - the difference in time on a 40K flat course between a 72.5 Kg rider (140 pounds rider  + 20 pounds bike) and a 70.3 Kg (140 pounds rider + 15 pounds bike) is 3 seconds at the same power threshold and same CdA

2009-04-17 10:47 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
jorge is completly right here, and something else to feed off this, and why you will see so many people telling you one off power testing, or comparing your numbers to others wont mean much, an example.


say my power meter reads 30 watts lower than it should, but it consistently reads this way. i use it for training for a year, i come back, my numbers are up, but still 30 watts under "actual numbers".

that doesnt matter at all, because i have been using a steady base to work from. in the end the actual wattage number doesnt matter as long as its consistent and you are using it to work from.

the PM on the bikes at my gym are wildly off from the SRM i use (i rode 50 min on one this winter and it said i ave 550 watts without trying too hard). but i bet if i used that on a day to day basis and went with their numbers, mine would slowly creep up just as with training with my bike/meter.

comparing your numbers to someone else outside of a watts/Kg is sort of like basing your nutrition off of someone elses weight and body fat%. doesnt really make a lot of sense;-)
2009-05-07 10:53 AM
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Subject: RE: Cycling power: how many watts does an average person pull?

JorgeM - 2009-04-15 1:04 PM
jeng - 2009-04-15 2:36 PM

JorgeM - 2009-04-15 12:32 PM
jeng - 2009-04-15 2:31 PM

Here's another datapoint for you, though I'm not sure how much it will help.

My threshold power is 231 watts and my weight is 55.5kg, so 4.16W/kg.

This website is good:

http://www.analyticcycling.com/

NICE! what level/cat do you race up there?

Cat 3. I'm pretty close to Cat 2... one more 5th or better could put me in it, but I'm kind of scared.

that's pretty cool, so you'll be Cat 2 in like a month then?

Hah, Jorge you were right. A 5th in a TT did it in less than a month.

Hi Ladies,

 

You have received enough upgrade points to advance to the next category. Because it is not mandatory for female riders to upgrade can you please reply to me via email if you wish to upgrade. If you wish to upgrade, your new license and plate numbers will be mailed  out to you and we will then make arrangements to get your old numbers back.

 

Congrats and good luck!

 

Krista Bergmann

Race and Events Assistant
Cycling British Columbia

201-210 West Broadway
Vancouver, British Columbia
V5Y 3W2

 

 



2009-05-07 11:39 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
Congratulations jeng! Nice work!
2009-05-07 11:42 AM
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Subject: RE: Cycling power: how many watts does an average person pull?
jeng - 2009-05-07 10:53 AM

Hah, Jorge you were right. A 5th in a TT did it in less than a month.



Congratulations!

2009-05-10 5:47 AM
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Subject: RE: Cycling power: how many watts does an average person pull?

dgunthert - 2009-04-15 4:18 PM...  Your position is going to have a HUGE effect on your speed for a particular wattage, especially on a flat course, where your weight has less impact. You might be pushing 200 watts to go 20 mph while the guy next to you with a better position may be pushing 10-20 watts or more less.

 

This isn't emphasized enough... specifically, for time trialists, w/CdA is much more revealing than w/kg, as a couple of calcs on analyticcycling will clearly show.

2013-03-06 3:22 PM
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Subject: RE: Cycling power: how many watts does an average person pull?
The way i calculated watts for human powered bikes back in the early 70s' Was by coasting tests down mountain grades measuring the time in seconds to Drop 1,000 feet in elevation & measuring the miles covered......................................................................................................................................... ( Gravity equivalent power in watts ) x ( Coasting time in seconds for 1,000' elevation change ) = ( 1360 ) x ( Total weight in pounds ) ......................................................................................................... This will take out all the math and give the mph to watts .................................................................. Watts for that person & bike @ mph for riding on flat ground
2013-03-06 4:55 PM
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Subject: RE: Cycling power: how many watts does an average person pull?

Palomarbob - 2013-03-06 1:22 PM The way i calculated watts for human powered bikes back in the early 70s' Was by coasting tests down mountain grades measuring the time in seconds to Drop 1,000 feet in elevation & measuring the miles covered......................................................................................................................................... ( Gravity equivalent power in watts ) x ( Coasting time in seconds for 1,000' elevation change ) = ( 1360 ) x ( Total weight in pounds ) ......................................................................................................... This will take out all the math and give the mph to watts .................................................................. Watts for that person & bike @ mph for riding on flat ground

 

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