I have Kreitler 4.5 Alloy rollers. Also have a Cycleops Fluid 2. I use the Fluid 2 way more, simply because I can mindlessly spin while watching a movie after I get back from work. Riding on rollers is something that requires you to be absolutely alert and focused. But it will definitely round out your pedal stroke. I use them both, but definitely favor the fluid trainer most of the time.