I have a Snap 2017 and recently purchased a Quarq PM. I ran 14 tests (workouts) and compared each workout to determine the difference between my Snap and the Quarq. I used the Snap’s erg and then recorded the same ride with the Quarq recording to my Wahoo Bolt. I then uploaded both .fit files into DCR Anaylzer Tool:
After all my workouts I found that my the Snap’s Erg and the Quarq were within 1% of each other. However, before every workout I ensured the tire pressure was the same (100 psi), the roller tension was the same (2 full turns once contact with the drum is made) and did a spin down calibration after warming up the Snap for 10 mins. I also of course calibrated my PM before every workout.
I noticed if I didn’t do a spin down calibration the Snap and the Quarq were off. I also noticed some slight variations if cadence slipped out of the norm, but nothing too drastic. I posted some of my early comparison below, but since then I’ve done more tests and the power profiles have been very consistent:
I recommend doing the same type of tests and comparing the power profiles. I also played with gearing to see if the power profiles matched better dependant on what gear I was in.