Power profiles

(I feel like I've written something similar to this before - I might be repeating myself but I have power on the mind having recently purchased a Quarq meter.) At the simplest level take a road event like a time trial. I have entered a few where the average power and the normalised power are the same value. The reason this happens is that, on a flat course anyway, power output is basically the same from the beginning to the end.
In contrast is an XC race. Climbing a hill the power levels might be 2.5x the event average, because on the descents there might be zero pedalling for many segments of the hill (and hence zero power). The average power will be much lower than the normalised power. Normalised power is often 50% higher than average. My Sunday ride was 170W average and 230W normalised power.

Normalised power compensates for the "difficulty" of the ride to give you an estimated average power that would produce the same fatigue level in your legs as the ride you actually did. Normalised power is used to calculate the training stress from any workout.

Another thing to look at is leg speed when the power is generated. Five hundred Watts in a standing sprint at 110rpm feels quite different from the same 500W generated at 60rpm during a seated hill climb.

A power meter can also inform your weaknesses. Did you get dropped going up the hill when the pace picked up, or flying along the flat roads after a longer period at this pace? The training response to each is quite different.

Answering questions such as these are why power meters are so ubiquitous on pro bikes these days. If every ride is instrumented with power, it is far easier to keep track of training loads and to focus on aspects of riding in training that are required for upcoming races.

After quite a gap without a power meter that can produce a left:right power split, I find on my new one that I'm a little right-centric. That was something I addressed years ago when my power meter did the split. My new DZero "knows" which power stroke is done with which foot and I've gone back to slightly-right sided. I'll have to pay attention to the left leg again.