Ditto to Mimi: Whether you have a double or a triple, you can't use all the gears are your rear cog in all of your combinations up front. You want to avoid as they say above, cross-chaining. That means you don't want to be in your little ring up front and your little gears (harder gears) in the back. Just switch to your next chain ring, i.e. when you start getting chain rub in the back, gear up in the front to your middle chain ring. Mimi is right, you should just about be able to use everything in the back from the middle. Occasionally, this won't work dependent on how big your cog differences are in the back, so you might not be able to use your last cogs in back on the small side and big side from your middle chain ring.

spoke