Why trust the safe transport of your bike to plastic carriers designed for short journeys on city streets? Front Runner's all steel Thru Axle Bike Carrier was designed 4x4 ready to get you and your valueable wheeled cargo to the world's best trails using the worldâ toughest roads.Fits 100mm x 15mm and 110mm x 20mm Thru Axles, as well as 110mm x 15mm Boost Hubs. And for you riders that go big, the rear tire holder fits up to 4.5â Jumbo Tires.