Saris Fluid 2 Smart Equipped Indoor Bike TrainerA Killer Training Combo What happens when you pair a speed sensor with the #1 selling bike trainer in the USA? You get a combo thats ready for any virtual or non virtual training ride. Its the ideal setup for budget conscious athletes looking to join fun, virtual communities, like Rouvy and Zwift, without a traditional smart trainer. Simply install the magnetless speed sensor on the rear wheel of your bike, mount your bike to the solid Fluid trainer