I'm 6' with an inseam just under 31 inches meaning I have short legs for my height. My cyclocross bike is a 54cm and is pretty much spot on. You are probably looking at the 54 to 58 cm range with a 56 cm as a starting point. The fit can be fine tuned with stem length and handlebar height. I list a large range because frame geometries can really vary quite a bit. As far as a hybrid I think 20 to 22 inches is about right (hybrids and mountain bikes usually measured in inches).