I'm very new to cycling (road bikes) and totally addicted, trying to absorb and learn as much as possible. My question is regarding hills.....I see lots of people say "the hill was an 18% climb or 7% climb, etc. How the heck do you know that!! Is there some device or maybe a funtion on your computer that tells you this? I have lots of hills where I ride, and I just like to know. Thanks.