I think most people fall at some point due to clipless pedals. I've fallen several times. But I've never wound up with more than a minor bruise or a scrape from it.
The most important things I've learned:
- Make sure you know which foot you put down first on intinct when you stop. I never really noticed this before I got clipless pedals, and for some reason just assumed it was my left foot. But it turned out I always put my right foot down first. That was my first clipless fall.
- Clip out well in advance of needing to put your foot down -- before you get to the intersection. Even if you're not sure you'll have to stop, clip out if there's a chance.
- Shift into an easy gear before you clip out. This will make it easier when you get started again, since you will be pedaling briefly with one foot clipped in while you are getting the second foot clipped in.
- When you are starting out and getting the second foot clipped in, start with the clipped-in foot high in the pedal stroke (around the 2:00 position) so you will get maximum momentum with that first stroke. Sit on the saddle immediately, then clip in the second foot. You will be more stable when you're seated, which will make it easier to pedal once or twice with one foot while clipping the second one.
- Practice clipping in and out on a indoor trainer to get used to the motions.
- Don't clip in with both feet when you're in slow-moving crowds, like at the mass start of a big organized ride or at an intersection with lots of pedestrian traffic.
As for knees, I've found that Speedplay pedals are good because there's more float with them.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles