Exactly. There was no need for the window since the astronaut was not in control of the capsule. It was purely PR. And how did those explosive bolts work out?

As for the case at hand, the OP's correct. The relative position of the bars, saddle and pedal is fixed at any angle of rotation of the bike, and all pedaling resistance comes through the chain tangent to the chainring; gravity plays no significant part in the mechanics of rotating the crank. If different muscle groups are used when climbing, it's only due to the difference in inertia and has nothing to do with the very slight change in the angle of the gravity vector.