Power and Acceleration?

drewjc

What does your HRM tell you when you start a descent or tailwind section on your rides? (i believe it would go up if you hold a steady power output???) From my basic knowledge of the figures associated with pedalling, power, force, torque, cadence etc. i would assume that the rise in cadence associated, with the required acceleration to maintain a steady power output has raised your perceived effort (and possibly your HR) beyond your comfort range.

The basic point is that cadence has a greater effect on perceived exertion than does torque. To determine POWER you simply multiply TORQUE x CADENCE, so if your torque is dropping on a downhill section then your cadence (the second variable) must increase to hold the same power, while the opposite is true for an uphill or headwind (ie. increased torque, decreased cadence). It is these changes in cadence that i believe are affecting your perceived effort. Many people don't realise cadence can play such a big part in determining HR.

In an ideal world with constantly variable gear ratios the gears would increase so that you could maintain a constant cadence (one that is comfortable for you to work at) with only your torque and actual speed changing.

The point is that your higher perceived effort is from an increased cadence and not an increase in torque. It is easier for the body to adjust to small changes in torque required but an increase in cadence upsets you more than you might realise.