Join Date: Mar 2010
Location: Miami, FL
Bikes: 08 Giant OCR C2, 05 Specalized Hardrock Sport Disk
keeping it under $200 sort of limits your choices. Also, depending on who makes the trainer resistance settings vary.
For the most part, fluid trainers offer the widest range of resistance. I have seen fluid trainers that offer 3,000 watts of resistance - which is more than anyone can crank out. Fluid trainers also offer the most realistic road feel, as the fluid itself increases resistance the faster you try to go.
Magnetic trainers are also decent. They offer varying settings as well. They fall short of a fluid trainer however.
Rollers are good in the sense that you do not need to attach your bike to anything. There is a roller under the front and back wheel. Pretty much you have a treadmill for your bike. The downside is that you can fall in your own home, which would be hysterical to put on YouTube should someone capture it on video. Roller trainers also take up a lot of space, so if you are short on floor space then this is a problem.
Fluid and magnetic trainers sometimes have resistance settings you can control from the bike - rollers do not. At least not that I know of.
And now for the fun part! Not all trainers are created equal. Although for the most part fluid is better than magnetic, I would rather have a good magnetic than a cheaper fluid.
As with everything else in the cycle world, you really do get what you pay for. Google "bicycle trainers" and there is all sorts of wonderful information you can wade through.