Choosing the correct size frame for a hybrid bike isn’t that much different from choosing a frame for a normal bike, or even a mountain bike. Essentially, you’ll need to compare your height with the frame measurements and find one that will allow you to pedal, mount and dismount comfortably. The general rule of thumb is that when you straddle the bike, there should be about an inch between the top bar of the frame at its highest point and you. So, if you stand 5’10” tall, for example, you’ll probably want a bike frame that is at least 19 inches tall or a large bike frame.