or try this (the ACSM formula that Coggan laid out in TRWPM):
do an evenly paced 4-5min effort
look at the “flatline” watts – where the effort stabilizes and you’re not sprinting at the start or the end of the effort.
watts x .0108 + mass in kg x .007 = liters of oxygen
divide ml of oxygen by body mass
recent 5 min effort:
412 x .0108 = 4.4496
71 x .007 = .497
4.9466 liters of O2
4946 / 71 = 69.66
The Garmin VO2 estimator has me at 70, so, it’s in the ballpark (that’s also what the last lab test I had said).
Take the estimates with a 5% grain of salt – but, lab tests can also have up to a 3% variance, depending the calibration and the competence of the tester, so there you go…
The most important number is the race result – after that, are the watts going in the right direction on your training rides?