For a while back in the late 90's I did a fair amount of biking in California-even raced a few times. Job and the realities of life set in, I moved to Mn. and then to NC. and my Bianchi had not moved (at least due to pedal motion) since maybe 1999. I'm now headed to age 65 and have decided to 'hit the road'. What is most unusual here is that I have owned a decent quality 'spinner bike' (I chose that type trainer because it tended to ride like a bike) for a couple of years now and my cycling conditioning is really not all that bad. Even my weight is about where it should be.
Back when I was riding in Ca. (Bay Area) I was always seeking out climbs which were easy to find. I'm not a small guy - 5'9" and 160 pounds generates a 32" (or smaller) waist. But I was an OK climber and just enjoyed the process. Given the rich number of 'climbey routes' available to me in the Bay Area (if climbey isn't a word it should be) riding a bike was mostly a series of 'long intervals' of mostly hard efforts for 5 to 15 minutes followed by rests, maybe a flat, repeat.
So my expectation was that my 'per unit of time' efforts on my spinner bike would be a higher level of work than on the road (due to the 'enforced' rest periods). I have must recently rehabbed my Bianchi and have ridden a couple of times, but now it is in the Sandhills of NC. I've been surprised here. In the area where I live there is rarely anything really flat for any distance. But everything is rolling so there are no climbs of consequence and no descents of consequence either. I went out for a ride (my second since the return of the Bianchi) and around 75 minutes fit my schedule well (first ride was a neighborhood/experimental thing just to verify that my bike handling skills sucked out loud). I did what I (vaguely) recalled of riding in Ca. and rode fairly hard pretty much all time where that was doable. On my typical rides in Ca. there would be numerous descents where 'work was not doable'.
Well, about 35 minutes into this ride I realized that I had been pretty much at my HRM AT constantly since I set out. I was totally whacked and completed the ride at a more reasonable effort level. I had anticipated that my 'trainer' work would typically be at a lower average level of effort than my 'road rides'. That was true in Ca. but I don't think it will be necessarily true here in my area of NC. Surprised me a bit.