Cycling Power

Well-Known Member
wiredued said:
Why don't they make it so you can enter your frontal area and continue getting watts on the flats and downhills?
Well, then wind would come into play. What they are doing is exactly what I tell my friends who don't have PMs. I tell them to find a hill of at least 5% grade and that if winds are light that they can accurately impute power from speed with the tools at analyticcycling.com. Upgrades slow down bike speed and reduce the importance of frontal area. As dhk said, power is required to overcome resistance and the primary resistance on climbs is gravity. If this device accurately computes grade, there's no reason it shouldn't be fairly accurate if there is light wind. But, if you ride the same hill for training, you don't need a PM or this device. Just go by speed.

dhk

New Member
RD, agree that hill climbing, ie, vertical rate of gain at low speeds, provides a more consistent way to estimate power for those of us who don't own or want to invest in power meters. For example, the hill leading to my house has a 175 ft vertical gain, with the main section of 10% average gradient, according to Delorme Topo. Going hard (about 90-95% of VO2 max) gets me a steady 8.7 mph on this section. Using the formula I provided above means my average power output for this short time results in (2 x 200 x 0.10 x 8.7) + 25, or 375 W.

But, as you said, since it's a known hill, the accuracy of the power estimate isn't really that important. Just need to look at the speed I can hold, or the time-to-climb to gauge whether two-minute power is improving or not.

Well-Known Member
dhk said:
RD, agree that hill climbing, ie, vertical rate of gain at low speeds, provides a more consistent way to estimate power for those of us who don't own or want to invest in power meters. For example, the hill leading to my house has a 175 ft vertical gain, with the main section of 10% average gradient, according to Delorme Topo. Going hard (about 90-95% of VO2 max) gets me a steady 8.7 mph on this section. Using the formula I provided above means my average power output for this short time results in (2 x 200 x 0.10 x 8.7) + 25, or 375 W.

But, as you said, since it's a known hill, the accuracy of the power estimate isn't really that important. Just need to look at the speed I can hold, or the time-to-climb to gauge whether two-minute power is improving or not.
I agree. I have a couple of friends who are using this approach to L4 intervals. They are using a 3.3 mile hill with ~5% avg grade. They don't have PMs, so they are using their speedometers to manage power on the climb and to gauge progress. One does have to be a little careful with longer climbs and avg grade because all climbs are of varying grade. If one climbs at a constant speed on a climb of varying grade, by definition he/she is riding at variable power and the physiological response is not represented by avg power but rather normalized power. But, that's actually a good thing since it is a faster way to ride the climb than constant power.

LookAt

New Member
For those of you who were wondering about the principle of operation of the BC401 instrument (road gradient and up-hill power meter) I have mentioned in my previous postings, and which I am still using with great satisfaction, I now see that at
www.clino.it
they have much improved the Home Page. They added an animation showing how the instrument displays slope and power.

velomanct

New Member
wiredued said:
analyticcycling gave me acurate watts I double checked my flat watts with mountain watts and they were within 6 watts of each other if I guessed my frontal area at .69 instead of .7 I think they would sync up completely. I'm 6' 1" 195 lbs on the brake hoods wearing baggy shorts. If you need to get elevations of a hill or mountain google earth maps has a beta that works pretty good it does occasionally crash though dsl or broadband is required.

you need topozone.com

google earth is not as accurate

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