Originally Posted by surak

Climbing on Zwift and every other major platform is pretty much spot on because the physics of it are easy to model, weight being the biggest factor.
In general Zwift is very generous with letting you use light and aero equipment while also assuming players use good aerodynamic position, so speeds are faster than in real life.

The hardest part is indeed cooling, with coasting coming a distant second on a smart trainer because no one will ever put out much power on downhills without trying extremely hard to do so.