" wrote in
oups.com:

Frame sizes seem to get more confusing all the time. The hybrid bike I
have now has a frame size of 22 inches. I like the size. I was looking
at a bike which I like. There was only one size on the floor, and it
seemed small to me. The sizes are 13,15,17, and 18.5.

These nominal sizes are often not very useful when comparing 2 different bike
models. For most people, a better method is to measure the distance from the
seat to the handlebars. Find a bike with a similar reach to your current
bike and take it for a test ride. Adjust the seat height and fore-aft
position so that you are well balanced on the bike. Also try one size bigger
and one size smaller. Remember that handlebars can usually be raised or
lowered somewhat, but not by a huge amount.