rollers or a trainer?which would be a better winter training device since i cant go outside anymore

Do you have excellent pedaling form, spin all day at 120 rpm? Then get the trainer.

If not, then rollers. But after a few weeks you'll want to get a trainer if you have just rollers.

I have both. The ratio of rollers:trainers is about 1:20.

My rollers have low resistance (4" drum, no resistance). Trainer is a fluid trainer.

btw if you want to be a sprinter, a fixed gear spin bike is great for working on jump and resistance (i.e. clamp down on the friction brake thing).

I consider myself a sprinter but I need base before I can work on top end stuff. I don't work on top end stuff until March. Before that I work on honing form and building base.

The trainer doesn't replicate sprinting form so it doesn't translate well. The rollers normally don't offer the resistance/stability necessary under 100% load. I haven't tried a full out sprint on free motion rollers but I can't believe that I'd be able to do a 100% sprint on a set but I don't know.

I was just telling a Cat 4 teammate Sunday that he should work on base until Feb or so, just do long miles, roll as fast as "moderate" feels. He should get faster and faster, just doing that (with the odd effort tossed in for jumping on a hill or whatever). Then when it gets warmer he can focus on more sharp efforts.

ty for that great advice,that is actually what im doing,spin classes almost daily and i have someone coaching me threw it,we are working alot of anaerobic stuff right now.and building a much better base

If I was into bike racing I'd get these for spring (yeah I know, I'm a season ahead of what you're asking):

^^^
Or you can just use a hill...