I bought the 13" based on the recommendations of CeeBailey's website. I'm about 5'11" and found the shield to be a bit short for my tastes, so I now have their 15". I like to look over the shield, preferring to have the windshield at a height where my nose would rest on the top edge (moustache level) . The 15" is just a tiny bit lower than that, which is good enough for me.