These bicycle training wheels, with 5 different distance install hole, fits most 12′-20’children bike. Select the suitable install hole base on your bike. the BikeHard 12-20 Training Wheels are completely adaptable to bicycles with wheels ranging from 12′ to 20′ and everything in between. Tough construction is apparent throughout all components: wheels, stabilizers, and hardware are made to handle the abuse of rough kids. Lightweight, adjustable, and durable, they are everything that one could ask for in a set of training wheels that can be handed down from child’s bike to child’s bike.