After spending too much time thinking about the meaning of cadence, I went off on a tangent and decided to do way too much math and science.

To do better math of course, I need better inputs. Since I don't have a power meter, I have been estimating power based on weight, friction, acceleration and drag. This are all reasonably easy things to estimate with some certainty and good data is available to at least get ballpark numbers. When I'm alone on my road bike.

Lately the only time I have to get out, I am towing my son in his trailer and of course its heavy, but does anyone have any reasonable idea what CdA I might have with a bike trailer?

Aside form the answer of buy a power meter. I suppose I could also learn some CFD, as I've already gone a bit overboard in my analysis...