Originally Posted by GreenAnvil

I'm talking my road bike on a trainer (either Qubo Fluid or Kurt Kinetic RnR, depending on which one is available as my wife uses the trainers too). No problem for me to hit 20mph outside and stay there for a while. Inside I seem to have to work harder at it and I'm burning out way faster.

Dunno but that's just me.

Edit: Case in point, although at a lower exertion level. My last ride outside was a recovery ride at zone2. A total of 28.86 miles at a speed of 15mph and avg cadence of about 70. But (and this is what's important), my avg hr was 123 and it hardly ever went above 132. Easy as pie and I felt that I could have done that all day. OTOH, my last non-interval hard session on the trainer, was just a few miles more (35) with an average cadence of 74. My avg speed was 15.8, *but*, my avg hr was 158, my max was 177, and I just couldn't wait for the session to end because I almost died. There's no way that 6+ extra miles at .8mph faster is going to make me suffer that much.

I don't mind it too much because the purpose of the trainer is to train, and in that regards it is helping me and challenging me A LOT. But for me, inside is way harder than an actual ride outside at any level.