The big challenges to a 13 mile commute are:

1.Sweating. If you don't cycle hard enough to work up a sweat, you probably won't have clothing issues. But that's a challenge for such a long commute. I happen to cycle hard into work, and generate quite a bit of sweat. To make matters worse, I've been using a backpack for the last couple weeks. Backpacks make your back sweat like crazy on a long commute. Because of the sweat issue, I have to take a makeshift bath in the restroom at work (using baby wipes), and change from my cycling clothes into a dry set of work clothes.

2.Is there anybody to come get you? If your tire tube is hosed, or your chain breaks, or a freak thunderstorm comes, who ya gonna call? If there is nobody, you have to properly plan for certain occurrences. Walking your bike for 6 ½ miles really sucks.

3.Where to put your bike? I am lucky enough to have a secure indoor location to store my bike at work. If you don't have a secure spot, learn how to properly lock up a bike, and hope that it doesn't get stolen despite your best efforts.

4.Not getting hit by a car. Learn all of the state and local road rules, and follow them. Use lights and reflectors. Be smart, alert, and anticipate what drivers are going to do.

Bike commuting is worth the effort though. It's true independence in your life. It's good for you. It's good for the world around you.