I participated in a PhD study last year investigating critical power testing in the lab and on the velodrome, with blood tests and VO2max and all that. I was coming back from some months off the bike with a smashed up ankle and was only just fit enough to be a test subject – pleased to say I’m usefully quicker now, especially on my preferred five minute bursts uphill or down. My 60 minute critical power came out as 230W which is 3W/kg. I’m not an XC racer though and the only road bike I’ve ever owned is a Brompton!
I’m quite curious to find out how I’ve progressed since then but tests like this are complicated/expensive if you’re not a voluntary guinea pig and it did take eight separate sessions and quite a lot of pain to get all the measurements. The VO2max test was a bit of a failure because I was on the scientist’s bike for the first time and had the saddle in the wrong place (quads burnt out before the rest of my muscles were going properly – I now know I pedal best seated way forward) and misjudged my best cadence (too slow!) however as I tend to climb standing up nowadays and all these tests required you stay in the saddle I feel there’d be further inaccuracy from that.