I'll second that 'good for you!'. You'll love it.

My commute happens to be six miles, one way, too. It's a great distance; not too short and not too long.

I'm not familiar with your bike, either. But I imagine it's a basic mountain bike and that's just right for the task.

In a nutshell, you want to be prepared for bad weather. The reason is that if you don't, then you'll not be able to ride the first time there's any chance of rain. And then you'll hardly ever ride. So you want fenders. Figure on about $25 (and up) for them. Another $25 for a rear rack. I use two (one on front) to be sure that I've got enough cargo carrying ability. I carry my stuff in a couple of medium sized (maybe 30 inch long) duffel bags that I get from the Beast of Bentonville for about $15 each. I give them a coat of Camp-Dri. And if it's really wet out there, then I put them in garbage sacks and strap 'em down. My stuff stays dry even in the worst weather.

I advise two mirrors; one on each handlebar. Most cars will be more courteous to you than you might think from our ranting. But there's some fool every here and there who will come too close and not even try to make a little space. You want to be able to watch these guys as they approach.

Tires depends somewhat on what you expect to ride on. I run near-slicks during the definite dry season. But this time of year I run on knobbies. If you're sure that you'll never be riding on that half-gravel/half-dirt stuff on the side of the road, then maybe you don't need knobbies.

For rain gear I buy very basic two piece rain suits. I leave one set as is for colder weather. The other set I cut off the arms at the shoulders and the pants at the knees for warmer weather.

Come on in and join us. You'll never regret it.