I will do Science to it

It takes a big person to use a power meter, which isn't to say that you need to have legs like Sir Chris Hoy to benefit from training with one. Rather, it is a reflection of yourself that is too true to be beautiful. Whatever ambitions and dreams you may have about your potential are leadenly anchored by numbers on a screen, often lower than you would hope.

I am borrowing a powertap wheel from a friend, and using it has been both informative and slightly disappointing, though its use as a training tool can hardly be overstated. I would be curious to compare the difference in times over time-trials from riders with power meters compared with aerodynamic wheels, because I suspect that simple knowledge of your effort would allow you to outperform even your best unmetered attempts.

As well as the training benefits, using a power meter has allowed me to check something that I had been wondering about for a long time - the accuracy of Strava power estimate. With the wheel on, I rode my standard loop and compared the measured power over segments with the two bracketing calculated values. Here's what I found:

Speed (low)	Power	%diff	Speed (measured)	Power	Speed (high)	Power	%diff
Climbs
34.5	280	-14.6	34.8	328	35.1	299	-8.8
28.3	263	-12.6	28.3	301	28.4	259	-14.0
Flats/rolling
34.4	206	-12.7	35	236	35	228	-3.4
34.1	196	-31.2	34.6	285	34.6	203	-28.8
34.9	215	-23.8	35.3	282	35.3	197	-30.1
35.6	242	-18.0	35.9	295	37.6	286	-3.1
Overall
32.4	214	-24.4	32.9	283	34.3	227	-19.8

Huh. So, basically, on climbs, Strava underestimates power, usually on the order of 10%. On the flats, though, it can be anywhere from 3% to 30%! The overall estimation was low by more than 20%.

Ok, so this isn't exactly science - more evidence is required. Nevertheless, I think I have showed 2 things:

1) You can't train with Strava

2) Strava tends to underestimate power.

Good trails!