Kink 2021 Roaster 12" BMX Bike. The Kink Roaster is designed to be a kid's first BMX bike. The 12" wheel and frame size make it an easy transition from a balance bike and means kids will feel completely comfortable on their first pedalling bike. Once again, this bike isn't simply a bike with 12" wheels or merely a miniaturized BMX bike. It factors into account standard BMX geometry and applies them to a younger child's size and needs.