Ahh, but what to measure...
At M2 Revolution, we focus on the most relevant fitness metric: how much power can a rider sustain for a given period of time - very simple, very direct, and easily tested with our CycleOps bikes which provide accurate and consistent measurement of power output, or shall we say fitness.
Many riders are drawn to Lab testing as a means to measure fitness. While this option can at times be useful, its drawbacks include that it is expensive, can be invasive, and often does little to shed light on the most basic of fitness variables - how much power can I generate for 20, 30, or 60 minutes.