This direct drive style bike trainer eliminates the tire-to-roller contact, and is capable of replicating any outdoor ride from conversational group rides to rolling hills to pain face inducing 20% grades. All of this is done with a smooth, road-like-feel thanks to a massive 20 lb. precision-balanced flywheel that replicates real world inertia better than anyone else. Paired with our innovative, rapid response electromagnetic resistance system and you ve got a bike trainer that can cover large resistance changes in a blink of an eye at a whisper quiet 64 decibels. Plus, the Hammer s revolutionary axle compatibility gives you the freedom to choose any thru-axle or quick release bike now and for years to come. Simply add a cassette, pop off your rear wheel, connect to your favorite virtual training software and prepare to Hammer away.