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Watts(3 posts)

Jul 31, 2001 6:00 AM
Is there any formula I can use to estimate my watts I put out? or do I have to buy one of those expensive trainers?

re: WattsBigDaddySmooth
Jul 31, 2001 6:29 AM
Unfortunately, we don't always ride in perfect conditions. Because of winds and undulating road surfaces, there is no formula that can be used but there is a way to estimate your watts. I own a computrainer so watts are always displayed. Of course, my computrainer can not accompany me out on the road so I compare my HR and watts from the computrainer and correlate that with what I'm doing on the road. So, I use HR as my guide, not MPH. Remember, your body understands time and HR, not speed, so don't concern yourself with what MPH you are going. But, to give you an idea based on your question, 25 MPH in perfect conditions and aero equals about 330 watts. 20 MPH = 200 watts. Once you break 25 MPH, the watts really soar so going from 25 to 26 is ALOT harder than going from 20 to 21. If you can go 27 you probably are pushing 370-380 watts and you'll need a license and race with the cat 1-2s. Going 30 MPH requires over 400 watts and let me tell you, it is extremely, extremely tough to hold 400 watts for more than a couple of minutes and I can hold 350 watts (about 25.6 MPH) for an hour. Finally, increasing watts above 330 is just like the MPH formula. 330 to 340 is tough, 340 to 350 very tough 350 to 360 and I'm at my limit. Each 10 watts reguires alot more effort. Hope this helps...
There's a website ...Humma Hah
Jul 31, 2001 6:44 AM
Analytic Cycling has all sorts of fancy calculations available at

On one of these, plug in your weight, speed, hill grade, etc, and out pops watts.

Have a calculator and some conversion constants handy: the site is all metric, giving speed in meters/second, weights in kg, etc.