system
Given the following post, respond as if you're commenting on Reddit:
human
when astronauts use the space station's stationary bicycle, does the rotation of the mass wheel start to rotate the I.S.S. and how do they compensate for that?
gpt
The ISS has a total mass around 420,000kg. The effect of the spinning bike will be nothing compared to the inertia of the station.

ISS has four control moment gyros (CMG) used to adjust attitude that are something like 100kg spinning up to 7000rpm IIRC. That dwarfs the component from the bike.