how does this relate to the power cubed statement/equation for increases in speed (change in speed is equal to power cubed???) ie if a 2mph increase in speed is equal to 2cubed then the change is2x2x2=8watts (which is so low its rediculous) and which here going from 221watts at 24mph then to 26mph the watts are275w( i believe to be correct), where is the cubing error because to go further and say 10 mph change is impossible to go to10x10x10=1000 watt change for 10 mph increase, and thanks robkit for the original data
how does this relate to the power cubed statement/equation for increases in speed (change in speed is equal to power cubed???) ie if a 2mph increase in speed is equal to 2cubed then the change is2x2x2=8watts (which is so low its rediculous) and which here going from 221watts at 24mph then to 26mph the watts are275w( i believe to be correct), where is the cubing error because to go further and say 10 mph change is impossible to go to10x10x10=1000 watt change for 10 mph increase, and thanks robkit for the original data
You're applying the math wrong, unfortunately. A 2^3 increase in power doesn't produce a 2mph increase in speed, but rather a *doubling* of speed. If you're going from 24 --> 26mph, that would be an increase factor of (26/24) = 1.0833. The power requirement should then be somewhere close to 1.0833^3 = 1.27 times. According to the data above, the actual power increase was (275/221) = 1.24.
Also, note that the aerodynamic portion of the power equation increases by a cubed factor, but there are other portions that only vary by speed^1, so the true power curve will not be a perfect y=Cx^3 curve. Hope that helps.
I was always wondering how come my speeds never match the speeds given power on analytical cycling.com. Are those speeds on time trial bikes? I mean 21mph at 155 watts?? Could someone please explain that. I tried surfing around on that site but to no avail thanks. 😕
I was always wondering how come my speeds never match the speeds given power on analytical cycling.com. Are those speeds on time trial bikes? I mean 21mph at 155 watts?? Could someone please explain that.
According to some posters that claim to have seen real-world test data from pro riders, the AC.com defaults do represent a *very* tight TT position.
You're applying the math wrong, unfortunately. A 2^3 increase in power doesn't produce a 2mph increase in speed, but rather a *doubling* of speed. If you're going from 24 --> 26mph, that would be an increase factor of (26/24) = 1.0833. The power requirement should then be somewhere close to 1.0833^3 = 1.27 times. According to the data above, the actual power increase was (275/221) = 1.24.
Also, note that the aerodynamic portion of the power equation increases by a cubed factor, but there are other portions that only vary by speed^1, so the true power curve will not be a perfect y=Cx^3 curve. Hope that helps.
Hope that helps .. hope that helps... of course that helps, i was applying the aerodynamic portion to the entire change in speed thanks a bunch 🙂
Hope that helps .. hope that helps... of course that helps, i was applying the aerodynamic portion to the entire change in speed thanks a bunch 🙂
🙂 . Well, the aero portion is the dominant factor while riding on the flats, so the overall power curve does 'closely' resemble a cubed function, as the example above shows. On an incline, the weight factor becomes increasingly important, which is a linear function w/ speed, as is rolling resistance (which is typically minor).
