Fitness coach Ben Cohn advises against reading while on a stationary bike. According to Cohn, you can either focus on the book, or you can focus on an intense workout. While reading, you're likely to get far less out of your session on the bike. However, for some, a stationary bike workout is too boring to stomach without some kind of reading material. Once you get past the jostling, it's not difficult to accomplish.
Set your book where you will be able to reach it once you've started your workout. If you sweat heavily, you may want to have a towel handy so you don't spot your book.
Get comfortable in your seat. Set up your workout program, if applicable.
Start your workout. Cohn advises that you wait until you're sufficiently warmed up and have your stride before reaching for your book.
Get your book. Rest it against the crosspiece of your handlebars, holding it in both hands. This will reduce the amount of jostling the book receives during your workout. Resting it with both hands also helps you keep your balance.
Every five minutes or so, look up and scan around the room. Your body's motion will make reading harder on the eyes, and you need to give them a periodic break.