A few days ago I did a test of three different power meters, Rotor 2InPower,Powertap P1 pedal and Tacx Neo turbo.
I thought I’d share the results as they may be of interest. I am sure others have done this as well in which case this will add to the data pool.
The tests were done on my “turbo bike”. This is a frame dedicated to indoor training, which I do 2-3 hours most days. So long as the chain turns I never do any maintenance apart from oiling the chain if it gets too noisy. (so it’s a bit of a mess)
Gearing for the tests was 54x11 and 54x15. The chainring is a Rotor Q so one other purpose of the test was to establish a baseline to test vs circular ring in the future. That said I would expect the results to be very similar. Both Rotor and P1 have high sampling rates and so should not suffer from the issues that some other power meters such as 4iii have.
6 runs were done. Each consisted of a ramp starting at 140W then increasing in 1-3 minute intervals by 30W to 290W then a final minute at 320W. This was done using the Rouvy workout function and for all runs the Rouvy app was only aware of the Neo. A Garmin head unit gathered the actual data used for this test.
2 runs were done for each power source. One on the 15 tooth at the middle of the rear sprocket, one in highest 11 tooth gear.
The table below shows the results of the tests. Numbers are from a steady state sample in the middle of an interval to avoid ramp up delay
The last 2 rows show the average watts and the % variance from target
The results are pretty much as would be expected. Both power meters give higher readings than the Neo since they are unaffected by drivetrain loss. These losses vary according to gearing and are present a picture not unlike that in other tests such as this.
Also as expected there is no evidence from this test to indicate that Q rings give different power readings from circular rings with the power meters used.