Offering a wide range of resistance and a smooth road-like feel--all at an approachable price--it's easy to see why the Fluid2 is Saris's best-selling trainer in the USA. The fluid resistance unit is quiet (64-68 decibels at 20mph), and offers a progressive power curve that increases the resistance as you shift gears and pedal harder, just like if you were on the road. Equip your bike with a Bluetooth or ANT+ speed sensor and you can use the Fluid2 with virtual training apps like Zwift and Rouvy.