Ergomo vs Power-Tap Data:
So I'm turning into a geek, but at least I'm a fit geek. The tempation to wire my bike with $2500 worth of power meter equipment was just too hard to overcome. It was even raining out and I went and did this just to show you how much I wanted to compare the devices..

I headed up Linden Drive in North Boulder and did 5 x 3' at my CP6 (@400w) with 3' recoveries. I ended up watching the Power-Tap more than the Ergomo because it was reading higher (but not too much as you'll see below).

I'll mainly let the data speak for itself..
The Data:

Ergomo: Power-Tap
49', 49'
581kj, 613kj
51TSS, 57TSS
290np, 305np
10.5miles, 11.2miles5
91 max watts, 614max watts
196 avg watts, 208avg watts
69 avg rpm, 71 avg rpm

Intervals:
Ergomo Vs PowerTap Difference
#1- 384avg w: 396avg w 12 (PT high)
#2-371: 388 17 (PT)
#3-361: 379 18 (PT)
#4-375: 397 22 (PT)
#5-394: 386 8 (Ergomo high) Very strange.. why would only one interval register high????

Here is a screen shot of CyclingPeaks with the two files lined up back to back and the intervals highlighted.







After all is said and done the Power-Tap obviously reads higher for me almost across the board, but not by much and certainly within reason. I'd rather go with the hgher numbers but this year I'll be racing with the Ergomo for the first time in seven years of using a power meter.
Ciao!
Dirk