@Stoke80 In my experience, there is no simple rule. Currently I mostly row on an erg or commute by bike. In rowing I had activities where 2 minutes were enough. But that was an sustained sub threshold effort followed by a ramp test. Never did an FTP Test on a bike. But I got an estimate when doing fun repeats across a bridge that crosses an express way. Those repeats were shorter than 2 minutes but in sum they resulted in feeling very tired. Both thresholds are different by approx. 20 beats when comparing cycling to rowing in my case. But quite stable within the same kind of sport. Did you try a ramp test or a longer sustained effort that pushed you to your limit already?
