To increase the front hub and front wheel stiffness on the road and cyclocross bikes, the cycling industry introduce the 12x110mm system in recent year. If your bike has a 12x110mm thru axle bike, you need our new 12x110mm boost size fork mount, to mounting to a TreeFrog rack. When you order a TreeFrog rack, you can order it with a 12x110mm thru axle fork mount. If you already have our rack, simple unbolt the existing fork mount with a 10mm open wrench and a 4mm hex wrench, and which out the original fork mount to the new 12mm thru axle fork mount using the original hardware.