To train for the LBS I bought one of these things off of Craigslist. I haven't embraced running in the cold and rain which, in Seattle, means I don't run much during the winter. Hence, I thought an indoor cardio option would be good. Treadmills are expensive and very large. Where this thing can be tucked away into a closet fairly easily. I had to buy a special skewer for the rear wheel so it mounts tightly with the trainer. It comes with one when you buy it new, but since I did the Craigslist route, I ordered the missing skewer off Amazon for like 10 bucks. It was easy to swap out.
So far, I really like the thing. I use my mountain bike. It's a carbon fiber frame but there hasn't been any issues with cracking or whatever at all. I have thrashed the bike pretty hard on trails so, it stands to reason, standing and riding hard on the trainer shouldn't be any worse for the bike. I did have to get a special smooth tire for the rear-wheel. The regular knobby tire caused crazy vibration and noise. It is still a little noisy even with the new tire. It's nothing that couldn't be solved by turning up the TV's volume. Oh, yeah. It sits in front of the Tee Vee.
You can adjust the tension by turning a knob on the trainer but for the most part, I set it up the one time and have only used my bike's gears to increase or decrease the difficulty. I have had it since November and it does the trick when I want to burn some calories and get a sweat going when the weather outside is gross. Hell, I do it when it isn't that terrible outside sometimes, too.