Robert Axle Project Thru Axles allow modern frames with axle mounting trainers to be used. Can be installed or removed using a 5mm Allen key. Measure trainer at the widest and measure bike frame width at the rear wheel hub. Application: Bike trainers. The Robert axle ends will extend 15mm past the frame on each side. Designed, built and tested in the USA. For use with bike trainers such as 1UP, Blackburn, Cyclops, Kinetic, Tacx and more. Important: Before ordering, make sure your specific elliptical trainer will use the width of the thru-axle fitted for you. Axle shaft and axle ends are machined from 7075 aluminum and hard anodized. Material: 7075 aluminum.