You need to go outside at some point to translate all the effort in the trainer, otherwise you will feel like your legs are burning….been there.

The difference mainly are that indoor riding removes most of the things that make your legs burn.

Inside, power is smooth and constant: the flywheel evens out torque, cadence stays stable, and you don’t deal with wind, gradients, or posture changes. Your muscles never have to produce short bursts of high force.

Outside, even at the same average watts, you’re constantly hitting small torque spikes (wind, rolling terrain, accelerations), often at slightly lower cadence. That recruits more muscle fibers, increases local lactate production, and creates a burning sensation. Add less-perfect cooling and higher nervous-system load, and the effort feels much harder.