Originally Posted by
genejockey
I also read that if you're a heavier rider, the maximum gradient is even less. Apparently the calculation of maximum gradient is based on something like a 165lb rider, but if you 200 like me, it applies more resistance at the same gradient - because that's what gravity does - and so your 15% max might work out to more like 12%. I know that my Kickr Snap, which supposedly can mimic a 12% gradient, feels the same to me at anything over about 9% on 100% trainer difficulty.
This is true and the calculation also assumes a minimum cadence (not sure what value though). So if you are a big guy, riding at a very low cadence then your maximum realistic gradient could be considerably lower than quoted. It all boils down to how much resistance the trainer can put out at low cadence.