On Bicycles, and.... what else is there?

When you think about power meters what professional team comes to mind? Only one... Indeed, there's a web site devoted to photos of Chris Froome looking at stems . Staring at his SRM display, many have claimed. Sucking the humanity of out racing by reducing it to pre-programmed efforts determined by power analysis? Hardly, obviously, but traditionalists always oppose change. He even does it in Pro Cycling Manager , a video game: So it's a major change in the world as we know it when it's leaked that for 2014, Sky is discarding their trusty SRMs for Stages power meters: Stages measures power on only the left leg, assuming the right leg is the same. This, not surprisingly, results in errors. I looked at Stages power data in this blog post . For example, comparing Stages power / 2 to Vector left-leg power is a good match, according to DC Rainmaker's data: But compare it to the Vector right leg data, and things get uglier: It typically takes two legs...

The last time I considered the constant cadence approximation as it applies to circular chainrings. Recall the principal issue is that the constant cadence approximation makes the following assumption for each pedal stroke: = × where ω is the angular velocity of the pedals, τ is the propulsive torque, and brackets signify a time-average. The error from this approximation is obviously: × − which is fairly trivially shown to equal: − ) × (ω − )> which is proportional to the correlation coefficient between torque and angular frequency, where a positive correlation results in an underestimation of power. Angular frequency is proportional to what I refer to as "instantaneous cadence": the rate at which the crank arms are revolving. So the issue comes down to whether the instantaneous cadence is correlated with applied torque, or similarly, if it's correlated with applied power (assuming applied power fluctuations are due more to torque changes than cadence c...