I'm thinking about investing in an indoor riding solution for those days/nights when it's raining, or I just want to ride some miles without worrying about traffic/stop signs/ufos/etc. So the question is, which do people think is a better investment: rollers or a trainer?

Currently the only bikes I own are fixies, and I hear they're harder to ride on rollers, but still willing to give it a shot.

It depends what your objective is, when you say indoor riding, do you mean for fitness or fun?

If fitness, I would recommend a trainer since you can adjust the resistance to a high level and really crank out the watts. The downside to a trainer is that it's very boring and monotonous, IMO.

Rollers are sweet because they're interactive, e.g. you have to focus on staying upright and they offer a more realistic riding experience. The main downside is that if you want to add mucho resistance you need to buy the fan attachment. True you can get rollers with a smaller drum diameter but it won't be as hard a trainer cranked up. Rollers will also do wonders for your balance, the first time can be a little hairy but after you get the feel for it, it's a piece of cake. Lastly, if you do decide to go with rollers Kreitler is the name of the game, a bit pricey but well worth it.

I much prefer riding my fixed gear on my rollers than the road bike. I find motivating to ride indoors very difficult though. I might buy cheap to see if you can hack the boredom, and then upgrading later if it's worth it. These just popped up on CL:

http://minneapolis.craigslist.org/bik/191224649.html

go for the rollers. riding a trainer is worse than a tunafish sandwich. seriously.

Rollers are fun until you get the hang of it, but the resistance only increases linearly (instead of exponentially as on the road), so you can't do intervals or sprints.

So it depends if you want to improve your handling and technique or if you are riding to improve your legs.

Either way, don't go cheap. Get the good shit, Kreiter rollers or Kurt Kinetic fluid trainers. Kurt trainers are actually deeeep discount at Freewheel, so now's the time to move if you are thinking you might ever want one! Then you could have both!

The Kinetic Trainer is really nice. I picked on up on consignment at the Hub last summer. When I went to the Velodrome, I saw the riders on rollers, and it looked like fun.

My only recommendation with the trainer is put a towel down, as you will sweat like a mofo.

Agreed. Either rollers or trainers make you incredibly hot because you don't have a 15-20 mph airflow. So get a big box fan too.

I was going to buy those, but after emailing the guy saying I wanted to pick them up on Wednesday he decided to sell them to somebody else on Tuesday.

Sucks for me, but I guess that's the world of craigslist.