Originally Posted by
Ironfish653
It's not really an 'up' stroke; in practice, it's more pushing forward over the top of the stroke, and pulling back across the bottom. Pulling up with one leg while pushing down with the other is something you really have to train for, like a competitive Track cyclist.
Clipless lets you ' pedal in circles' more easily (you don't need to focus on keeping your feet in place on the pedals). Pedaling 'circles' doesn't really increase your power, since your whole system can only put out a certain amount of watts, but what it does do is take some of the peak loads off of your quads (the primary drivers) and spread it out to the other muscle groups, like hamstrings, calves and glutes, so that you're putting less maximum stress on a single muscle group.
It can make a noticable difference on a long, steep climb.
I agree with this. There are flat pedal setups that allow you to "pedal circles" pretty effectively too (they easily have enough grip to push forward over the top and pull back across the bottom), but for road use I do much prefer clipless myself. They are lighter and very secure.
I was just pointing out to the OP that it's not about trying to pull up on the upstroke as they were thinking. Studies of professional road cyclists have shown that even they don't do that. The best you can do on the upstroke at any normal cadence and power is to unweight your leg to prevent it from having a negative power contribution from its own weight as you raise it against gravity. For that purpose you don't need clipless.