Originally Posted by
msu2001la
Also worth noting that some Zwift gradients exceed the limit of most trainers. Kickr Core maxes out at 15%, for instance. There are portions of the radio tower climb that are 16-17%. There's a section on Richmond that is over 20%. These will all feel like 15% on a Kickr Core, even at 100% trainer setting, but your avatar will ride slower based on the steeper grade.
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.