Power Readings: Powertap P1 vs Stages

From now on I will be using the PowerTap P1 pedals. But before I made the switch completely, I wanted to compare the power difference between the P1 pedals and the Stages crank arm that I have been using for the past two years. To conduct the test I paired my Stages crank arm and P1 pedals to separate ANT+ bike computers. I then calibrated both power meters. I warmed up for a bit, and then spent some time in each of the various zones that I work out most often in. I did my best to lap each device as quickly and as closely together as possible. Here are the results: Anaerobic Capacity Intervals:

Interval Length: 30s 30s 30s 30s
Powertap P1 458 459 470 455
Stages 444 443 452 446
L/R PWR Balance 49/51 (224/234) 49/51 (225/234) 49/51 (230/240) 49/51 (223/232)

 

High End Vo2Max Intervals:

Interval Length: 1min 1min 1min 1min
Powertap P1 442 446 445 443
Stages 430 433 434 435
L/R PWR Balance 49/51 (216/226) 49/51 (218/228) 49/51 (218/227) 48/52 (212/231)

 

Low End Vo2Max Intervals:

Interval Length: 2min 2min 2min 2min
Powertap P1 410 410 411 410
Stages 405 408 409 411
L/R PWR Balance 49/51 (201/209) 49/51 (201/209) 49/51 (202/209) 49/51 (201/209)

 

High End Lactate Threshold Intervals:

Interval Length: 4min 4min
Powertap P1 379 381
Stages 382 384
L/R PWR Balance 50/50 (189/190) 50/50 (191/190)

 

Mid Range Lactate Threshold Intervals:

Interval Length: 8min 8min
Powertap P1 355 359
Stages 361 361
L/R PWR Balance 50/50 (177/178) 49/51 (176/183)

 

Low End Lactate Threshold Intervals:

Interval Length: 12min
Powertap P1 345
Stages 347
L/R PWR Balance 49/51 (169/176)

 

Cool Down:

Interval Length: 8min
Powertap P1 206
Stages 212
L/R PWR Balance 51/49 (106/102)

 

All in all I am impressed with how close the two meters are to each at all power outputs. It appears the Stages meter reads higher at lower outputs, and the Powertap P1 meter reads higher at high outputs. Somewhere in the 380-390w range they seem to be in agreeance with each other.

Update on February 18th:

Easy Ride:

Interval Length: 70min
Powertap P1 240
Stages 243
L/R PWR Balance 52/48 (125/115)