How do you trim leg hair?

I use regular hair cutting hair clippers with whatever guard you want to use to regulate the length that gets left behind. Mine were like $10 at Wal Mart. I tend to use the shortest guard and go against the grain. You'll have to experiment to see what angle works best for you. Around the knees is a little more difficult sometimes because of the valleys. Bending your knees (maybe sit down) can help with this. I'm a hairy legged guy -- I don't like the overly shaggy look and the wife doesn't like the shaved look (I cycle, too). So I keep it somewhere in between.