I actually knew this (of course), but it wasn't ingrained in my mind enough to always be aware. I think I'll remember now Out for what I was hoping would be a 60 miler on the Nashville greenway, 3.5 miles in I'm going around a 120 degree left hander and BAM! down to the pavement I go at about 10 MPH. Stuff flies everywhere, gel, Clif bars, batteries. Get up and blood is pouring out of both legs, left one at the kneecap and right one on the calf muscle. Road rash on the left elbow. What happened? You know it, I stupidly was either pedaling around the corner or went around the left hander with my left pedal down and it grabbed the pavement and dropped me. I had fairly recently changed to bear trap style pedals and let me tell you, they also grab the pavement well! I'd been around that left hander at least 50 times in the last year with no problem. So, now hopefully it's ingrained in my mind to keep the pedal up in the direction you're turning.
My right calf caught the front sprocket and I have a nice row of sprocket teeth marks up the calf. Most are superficial, but right in the middle I have a couple that dug deep and ripped into the muscle pretty good. I didn't get that bleeding to stop for a couple hours after a bandage was applied. And that one hurts pretty bad. I can't flex the calf at all so hobbling around. Right knee got a 1.5" deep abrasion with some moderate scraping below it. It was bleeding profusely, too, but was easier to get stopped. I had a couple of bandannas with me and wrapped each major wound along with a handful of band-aids. By the time I got back to the car blood was running all down both legs, socks and shoes were red with blood and both bandannas were blood soaked. Looked pretty gnarly.
So, watch your pedals if you aren't already! Falling can hurt!