Robert Axle Project axles allow modern frames to be used with axle mount trainers. For use with bike trainers such as 1up, Blackburn, Cyclops, Kinetic, Tacx and more. IMPORTANT: Before ordering please make sure your specific trainer will fit the width of the push axle equipped bike you are using by measuring the trainer at the widest setting and measuring the width of the bike's frame at the rear axle. The ends will extend 15mm past the frame on each side axle and the axle ends are machined from 7075 aluminum and hard anodized. Installed or removed with a 5mm allen wrench. Designed, built and tested in the USA.