The simple solution is to not let it bother you. It's probably best not to get all stabby and try to fight every driver on the road.

I usually don't have too many problems with drivers...but I had one instance where some jackass yelled at me to "*** get off the *** road" (of course on a not busy road with 2 lanes in each direction and a 35 mph speed limit that snakes through a series of neighborhoods). I was not in a very good mood, so I busted my ass to catch up with him. At the next stop light, I politely asked "Excuse me sir, is there a problem? I couldn't quite understand what you were yelling back there? Should I call the police? I already took a picture of your license plate, so it would be really easy to direct the police in case there is some sort of problem." (all while holding onto to my cell phone) The driver didn't know what to say, just kind of stared at me, shrunk down in his seat, and finally muttered "uh uh uh no, no problem." Guess he wasn't expecting a confrontation and just wanted to anonymously be an *****hole to someone.

It probably wasn't the best way to handle the situation, but it at least made me feel better. Generally, I just ignore the idiots. I live in a college/yuppy town, so there are a lot of people on bikes and in most cases, everyone is pretty nice to you.

And to the original poster's comment, I would just go the 3 mile route to the gym. I mean, you're going to the gym anyway, why not get your heart rate up a little more? It's like when you see two people fighting over a parking spot at the gym because neither wants to park an extra 20 feet away...you're going there to workout...you're going to spend 20 minutes on the elliptical trainer anyway, what's the big deal?!