Jeff wrote an answer about CycleOps Fluid 2 Trainer on July 13, 2011
There should be a hand-tighten nut on the lower side of the metallic cylinder that the rear wheel rests on. Turning the nut raises or lowers the cylinder unit, thereby adjusting the pressure exerted by the wheel on the unit. You may have to start out with less pressure to allow the wheel to be secured in the hub mating mechanism. Then, once the hub is locked, you can tighten the pressure to fit your needs.