Travel Trac Comp Fluid Bicycle Trainer Fluid resistance produces progressive resistance for a smooth, quiet, road-like feel External flywheel facilitates smooth and efficient pedaling action Wide, stable base provides solid performance during hard efforts Easy setup -- no assembly required Frame folds compactly for storage or transport Progressive resistance increases as you increase speed, simulating a true road-like feel. Internal disc spins in fluid for smooth, quiet and affordable performance. Folds up to be a mere 5.5&#034; wide. Perfect for easy storage or transportaion. Unfolded, the trainer&#039;s wide stable base provides solid performance during hard efforts Accommodates most road and mountain bikes Includes a rear quick release skewer to ensure proper bike fit