I'm always amazed by the leg lengths posted in size threads...all of these folks who are 5'8" claiming a leg length of 30 inches, or 5'9" claiming a leg length of 31 inches.

"Leg length", for cycling purposes, is measured from the floor to the pubic bone. The average guy who is 5'8" is usually has a leg length of 32 inches or 33 inches, except here at "Bike Forums".

An easy way to skip the whole measuring process is just spend some time at your neighborhood bike shop. Stand over a couple of bikes with your belt buckle up against the back of the stem.

If the top tube is pressing into your crotch, the frame is too tall. If the top tube lightly brushes your crotch, take the bike for a test ride. If you feel too stretched out riding that size, test ride the bike one size smaller. You can learn more from a five minute test ride than from five hours of reading opinions of the internet from folks who don't have your leg length, and don't have your bike.