I'm currently using a Performance brand fluid trainer that I got for under $100 new and I'm happy with it for my purposes. I've never been on rollers but I'm interested in them for the core stability, skills, road feel and less wear on tires aspects compared to trainer. My question is how much of a work out can you get on rollers using simple bare bones rollers? I know the resistance will not be the same as trainer but if you are riding rollers in highest gear will it give you a reasonable work out? Do people mainly use rollers for short sessions like warming up for races or can you do a 45-60 min session?