Today it’s my first day with Zwift:
I’ve started riding with my Powertap Powercal HR strap. I had low expectations because I read that things were not going to go adequately, but the experience was even worse than I expected.
I use a spin bike for indoor riding, so I have attached a cadence sensor also to my crank (considering that the speed sensor does not make sense because pedals turn at the same cadence than the main wheel, so it’s extremely easy to calculate the speed just by considering a circumference of the wheel for example: ~2 meters/revolution x 100 RPM x 60min = 12km/h). This speed is raw and imprecise, considering no gears and no resistance, and also considering that in case that we offered a certain power with a different gear than the single gear that spin bikes provide, the RPM of the wheel could be way faster than the cadence of the pedal.
But I’m saying this because of the cadence of the pedal in any Spin bike, is exactly the same as the cadence of the wheel, so it’s pointless to use a speed sensor in the wheel.
The calculation of the real speed could be done by estimating the % of the slope, the power, and the cadence: High power + High Cadence + Low % Slope = Extra Speed.
I thought that the software considered this formula: Cadence x Power x Slope = Speed.
But I have discovered today, that the software it’s only using the Power output of the Powercal. Therefore, the bike moves even when I’m on the floor with 0 rpm cadence (so basically it’s saying me, that it doesn’t use the cadence for any calculation at all).
Most of the power meters (pedal, crank or trainer), give a near exact calculation of the speed because the power-meters have a cadence sensor in the power meter installed and also, because power it’s only measured when there is movement in the meter, not by external factors.
But Powercal, obviously, does not have this cadence sensor because it only measures the power estimated, based on the HR variations.
So for example during a Zwift workout, the software said: “Go over 600kw for 10 seconds”: It was impossible: I could extremely increase the cadence of my bike, for example from 80 rpm to 130rpm and obviously this should have been a great variation in my HR (for example from 150 to 160 in 5 seconds). But if the software does not have any correlation between cadence and HR variation it’s impossible that the Powecal increases the total power output over 300-350 kw in that amount of time (10 seconds)
I understand that Powercal it’s not meant for Zwift, but I know for sure that there could be software solutions to offer a great experience by combining Powercal output with a cadence sensor for indoor spin bikes experience (or any other indoor bikes)
But being realistic, and considering there is not going to be a solution anytime soon, I would like to know if anyone has found an interesting alternative to have fun with Zwift while using this equipment.
Obviously, at this point I should discard all Zwift workouts because they are meant for adequate power-meters. I wondering alternatives right now, for example, doing an spinbike class while “having fun” riding in the Zwift landscapes. It’s not the full Zwift experience, but it’s an idea.
Any other ideas to share with me?
Thanks for reading!