Power difference - indoor Vs outdoor - Page 15

Originally Posted by frenchyge

Some random thoughts from tonight's trainer session.

85.5kg rider doing 20mph up 1% slope on road vs KK Road Machine:
Resistance
==> same for both, since KK resistance is calibrated to match road conditions for this assumed 'average rider'.
Power
==> same for both, since velocities and resistances are equal -- 262w.
Kinetic Energy
==> Road = .5 x 85.5kg x (8.94m/s)^2 = 3417Joules (neglecting rotational energy in wheels)
==> Trainer = .5 x Moment of Inertia x angular velocity^2, where moment of inertia for trainer flywheel and rear wheel = .5 x mass x radius^2
Flywheel energy = .5 x [(.5 x 2.84kg x (.0825m)^2)] x [(8.94m/s) / (.17m roller circ) x 2pi]^2 = 528Joules
Wheel energy = .5 x [(.5 x 1.5kg x (.35m)^2)] x [(8.94m/s) / (2.2m tire circ) x 2pi]^2 = 30Joules
Total Trainer KE = 528 + 30 = 558 Joules

Kinetic Energy on the trainer is 1/6 that of the road rider, despite the fact that resistance and sustaining power are equal. One could make them equal by increasing the flywheel mass by 6.4 times to 18kg, by making the original flywheel 2.5 times larger in diameter, or by reducing the inherent trainer resistance such that the rider pedalled 50.7mph to generate 262w. A 'heavy wheel' would have to be much heavier than 18kg, because of the much slower rotational speed.

In order for road KE to equal that of the trainer, rider velocity would have to slow to 8.77mph on the road. To generate 262w at 8.77mph, the originally assumed 'average' rider would be riding up a 6.9% grade. Ever wonder why riding on a trainer feels similar to riding uphill?

Originally Posted by rayhuang

I have a very important question (to me anyways-hopefully others). I did max sprints today, but due to fresh snowfall and low temps I did them indoors on my KK. I can only produce ~860 watts in an all out sprint on the KK, but 1200 on the road (and very early in getting back on the bike) so I assume that 4 months later I should be above 1200. Also-my 5 second power is way down as is my 10 second power compared to the road, but the PE and max HR I hit are no different.

Now that youve got the background, my question is, have I cheated my muscles by doing the workout indoors and losing about 400 watts max on what I am capable of? Or does the power output not matter as long as the effort was 100%?

I really would like to know and TIA,
Ray

Originally Posted by rayhuang

I have a very important question (to me anyways-hopefully others). I did max sprints today, but due to fresh snowfall and low temps I did them indoors on my KK. I can only produce ~860 watts in an all out sprint on the KK, but 1200 on the road (and very early in getting back on the bike) so I assume that 4 months later I should be above 1200. Also-my 5 second power is way down as is my 10 second power compared to the road, but the PE and max HR I hit are no different.

Now that youve got the background, my question is, have I cheated my muscles by doing the workout indoors and losing about 400 watts max on what I am capable of? Or does the power output not matter as long as the effort was 100%?

I really would like to know and TIA,
Ray

Originally Posted by TiMan

In some ways sprinting o the KK is superior as it teaches you to focus on the most important element in a sprint which are all out explosive effort with the LEGS.

Originally Posted by rayhuang

Yes-I did exactly that-I concentrated on explosive moves with the legs like a seated stomp with less upper body input.

doctorSpoc-thanks as well. I do seated stomps on the trainer and this winter I have had many, many 11 hour weeks on the KK.

I did have to get off after the first sprint and tighten the tensioner knob a half turn (3-turns total), but still got a little wheel slip on the first push, but that was about it.

Ray

Originally Posted by TiMan

Stomps are fine but they are not sprints...they are a muscular workout which is good but not a sprint...... do some real sprints on the KK. Get out of the saddle and explode(tighten the knob way down) and then do as the doc said....focus on the seated part of the sprint really well and hammer as hard and as fast as you can. The good doc also mentioned seated accelerations which are in essence sprints in the saddle and in the small ring....small ring sprints. These are really good.
Neuromuscular training with sprints work on a KK but to get a good technical sprint you must do sprints outside on the road. So you CAN build a good sprint on the KK "power/effort wise" and then it should not take long to refine the sprint once you get outside again.
Of course nothing beats the real Macoy of outside sprints but if you can afford emotion rollers then you can throw the bike around indoors and not fall off the rollers...these rollers are unique and super good.