Low wattage at higher RPMs with Elite Suito T

Bugs and Support
#1

Hi. I have an Elite Suito T. Firmware is all up to date and I recently calibrated it.

I’ve notived that my wattage seems to be quite low when I hit higher RPMs. As an example, today I was riding at a heart rate of about 110 bpm, with 120 w, and 85 rpm. I then shifted to an easier gear, and was going about 95 rpm. My heart rate remained the same and the effort felt more or less the same, but my wattage dropped from 120 to 95. The gear that I use is small but I still feel enough resistance on it, although I am not quite sure if the resistance is the same on the trainer as it would be on the road.

Is there a (good) reason why my wattage seems to drop so much on high rpms? It seems so much easier to reach higher power when I use a gear that feels slightly too big as well.

#2

It depends on the gear you changed to. Power is generated by two things Force on the pedal and rotational speed. When you are in a lower gear the wheel speed is much lower therefore lower power even if you apply the same force.

See the image below.

Lets say you are on a 17tooth on the cassette doing 80RPM your wheel will spin at 29.7km/h then you shift to a easier gear 21 tooth and increase to 90RPM then your wheel will be slower at 27.1km/h, therefore less power.

image
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#3

Thanks for your reply! So basically what you’re saying is: even though I might feel as though I’m doing the same effort and my heart rate is pretty similar, in fact I AM generating less power and going slower? Shouldn’t my heart rate drop as well then? And isn’t the difference in power between 120 and 95 watts quite large? That means I’m basically doing 20% less.

#4

It depend what wat the gear change.

HR is not a good indication of work done. High cadence tend to raze the HR a lot more than low cadence. I can do higher power at low cadence with the same HR.

#5

So why would riders like Chris Froome or Lance Armstrong swear by high cadence? It must somehow be beneficial!

#6

Because they have more fast twitch fibers and are very fit.

What was the gears you used?

This is by dropping 4 gears and the wheel speed is lower, thus lower power.

image
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This image show a trainer power profile. X=wheel speed. Y= Power
As wheel speed increase the power increase.
image

#7

well I have a gravelbike with a Shimano SLX cassette, 11-42: 11-13-15-17-19-21-24-28-32-37-42
So I was probably riding on the 17 and shifted to the 19
On the climbs it also happens, there I probably go from the 28 to 32 to from 32 to 37 depending on how steep it is

If I follow your gear chart though, shifting up one gear means I should usually be going faster at 90 RPM as opposed to 80 RPM

#8

Yes wheel speed should go up a fraction.
Gear 17 @80RPM = 29.7 km/h wheel speed
Gear 19 @90RPM = 29.9 km/h wheel speed
Thus the wheel will spin 0.2 km/h faster thus generating a fraction more power

Remember we are talking wheel speed to generate power - this does not indicate in game speed.