# Am I really that weak?



## funktekk (Jul 29, 2006)

I broke down and started my trainer workouts for the winter.

My trainer (Elite TDF edition) has a wattage readout, but I have never really used it. I have made it my objective to start training with power on the trainer to see if a powertap is a worthy investment. So before I go through the tests to set my parameters I figured I'd do some leg speed intervals just to see where my watt is at.

Well to my surprise I found that I was struggling to put out 100 watts. I am not the strongest rider but I usually don't struggle to stay with the faster group rides in the area.

Is there something wrong with the trainer or am I just weak?


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## Argentius (Aug 26, 2004)

100 watts is nothing, for a rider with any kind of fitness.

I mean, not nothing, but it shouldn't be hard, at all. It's got to be the trainer.


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## boon (Dec 14, 2005)

that doesn't sound right. i have an Elite Wireless trainer with power and 100W is doing something like 39/23 at 90rpm.


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## wim (Feb 28, 2005)

*Your trainer's lying.*

For the average rider on level ground, 100 watt are good for around 13 mph—which agrees with boon's figures. If you know how fast you can ride out on the road by yourself, you can use the linked calculator to estimate the power you're putting out. Make sure you select "tops" or "drops." 

http://www.kreuzotter.de/english/espeed.htm


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## funktekk (Jul 29, 2006)

Well I wonder what could be causing the error. On my solo training rides I average 20mph (its really flat here). 

I had the trainer cranked to the highest resistance (5) and I was doing 110-120rpm in 39/16 (I think).

I guess if I can't get it worked out I'll just us the watts as a reference point for intervals, provided that it is close to linear.


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## wim (Feb 28, 2005)

I don't know your trainer, but significant readout errors on some trainers can come from a less-than-ideal bicycle-to-trainer connection (excessive tire slippage or -deformation).


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## scmtnboy (Aug 22, 2006)

It seems there must be some problem with the readings as others have said. If and when you are able to find the problem see if you can have someone with a calibrated power meter ride on your trainer and compare the power readings.


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## MR_GRUMPY (Aug 21, 2002)

Your trainer is not measuring Watts. It is just guessing, based on speed and resistance settings. If your resistance settings are off, just a little, your Watt figures will also be off. Don't think of the read out as 100 Watts, just think of it as a number that you can use to compare workouts.


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## msohio (Feb 23, 2004)

*Calculator-Win*

Wim.......The calculator you reference is very slick. Have you or someone matched the result off the calculator to your actual wattage readout on the road off a power meter?? I don't have a Power Tap or the like, so I've never known what my wattage is. And I've never tried ride the same gear and speed with someone that does. With this calculator, one could set up a section of road and make it one's "output" course. Way cool idea, thanks.


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## Speedi Pig (Apr 18, 2004)

Here's a web site that will let you _estimate_ power.

http://www.kreuzotter.de/english/espeed.htm


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## wim (Feb 28, 2005)

msohio said:


> Wim.......The calculator you reference is very slick. Have you or someone matched the result off the calculator to your actual wattage readout on the road off a power meter?? I don't have a Power Tap or the like, so I've never known what my wattage is. And I've never tried ride the same gear and speed with someone that does. With this calculator, one could set up a section of road and make it one's "output" course. Way cool idea, thanks.



I've never owned a power meter either and am not interested in getting one—too old and slow now. A long time ago, I was a very minor player in a study group that worked with force-measuring pedals and power meters in an indoor, stationary test environment.

I agree, it would be interesting to see how the kreuzotter.de or any other calculator stacks up against actual power output on the road. I imagine that a power meter on the bike is fairly accurate measuring raw power a cyclist puts out, but can the on-the-bike power meter tell how much of that power actually translates into forward propulsion? If the on-the-bike power meter can't, matching calculator wattage with power meter wattage might be more complicated than it first appears.

I don't know enough about on-the-bike power meters to think this through. I'm sure someone here will know what the relationships are between calculated, _required_ wattage and actual power _output_ readings from an on-the-bike power meter.


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## Kerry Irons (Feb 25, 2002)

*Power to the tires*



wim said:


> I agree, it would be interesting to see how the kreuzotter.de or any other calculator stacks up against actual power output on the road. I imagine that a power meter on the bike is fairly accurate measuring raw power a cyclist puts out, but can the on-the-bike power meter tell how much of that power actually translates into forward propulsion? If the on-the-bike power meter can't, matching calculator wattage with power meter wattage might be more complicated than it first appears.


Bike power meters (iBike not included) measure either the power applied to the cranks, or power applied to the rear hub. There is about a 2% loss of power through the chain, and virtually none through the wheel. So, power meters are telling you how much power is required to propel the bike. IME, the kreuzotter site estimates high - maybe 15%, though I didn't check it in detail once I saw the numbers were so far off. Analyticcycling seems to be pretty accurate in that the power numbers you see for various speeds agrees with what the analyticcycling site calculates.


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## magnolialover (Jun 2, 2004)

*Guys...*



funktekk said:


> I broke down and started my trainer workouts for the winter.
> 
> My trainer (Elite TDF edition) has a wattage readout, but I have never really used it. I have made it my objective to start training with power on the trainer to see if a powertap is a worthy investment. So before I go through the tests to set my parameters I figured I'd do some leg speed intervals just to see where my watt is at.
> 
> ...


Guys, stop fibbing to this guy.

The answer is pure and simple. 

Yes, you are that weak. Give up the sport immediately, if not sooner.

/by the way, just kidding.


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## wim (Feb 28, 2005)

Kerry Irons said:


> Bike power meters (iBike not included) measure either the power applied to the cranks, or power applied to the rear hub. There is about a 2% loss of power through the chain, and virtually none through the wheel. So, power meters are telling you how much power is required to propel the bike.


Thanks. I imagined bike power meters to be more complicated than they are. Time to do some reading and close a knowledge gap.


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## ilan (Nov 27, 2006)

Get a PowerTap, I have one and it works well, and is especially convenient for a trainer, because it has the speed sensor built-in to the rear hub already, no need for an extra transmitter. 

I'm not in particuarly good or bad shape, but 100W on my trainer is fairly easy, though not as easy as on the road. As has been discussed previously, Wattage on a trainer will usually be less than on the road for an equivalent perceived exertion. At 100W on my trainer, my heart rate is about 125-130 whereas I would be at 120W on the road for that HR. 

Since you can ride about 20mph on the road, you are putting out probably 150-200W at that speed, depending on conditions, so the problem is with your ergometer. 

-ilan


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## root (Sep 13, 2007)

*Something is wrong...*

I'm a pretty weak rider (my FTP is only 250 Watts), and 100 Watts is below my recovery L1 level (i.e. easier than easy). You should barely feel any resistance when spinning 105 RPM to produce 100 Watts.

I'm not sure why your trainer seems to be that much off. Could it be that it needs a warm up? Some trainers are known to make power measurement errors until they reach working temperature (but I don't know if such significant error though)?


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## ilan (Nov 27, 2006)

root said:


> I'm a pretty weak rider (my FTP is only 250 Watts), and 100 Watts is below my recovery L1 level (i.e. easier than easy). You should barely feel any resistance when spinning 105 RPM to produce 100 Watts.
> 
> I'm not sure why your trainer seems to be that much off. Could it be that it needs a warm up? Some trainers are known to make power measurement errors until they reach working temperature (but I don't know if such significant error though)?


Thanks, my FTP is also about 250.... It's different on a trainer though, I almost had a coronary trying to maintain 240W for 4 minutes on my trainer, when I had an easier time averaging 280 on the road for 7 minutes. As I said, 100W is above my recovery level on the trainer, though it's below on the road.

-ilan


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