Record wheel and tire size
Read the markings on the tire sidewall and measure the installed tire's actual width. Rim width and inflation can change the real measurement, so do not select only from the model name.
Inspect available clearance
Check space above and beside the tire at the fork crown, seatstay bridge, chainstay bridge, brakes, and cables. The wheel and guard must remain clear during steering and normal frame movement.
Match the mounting system
Identify eyelets, bridge holes, fork mounting points, and axle style. Clip-on, strap-mounted, and full-length guards use different attachment methods and are not interchangeable in every frame.
Recheck after installation
Spin both wheels and turn the handlebar through its full range. Make sure hardware is secure and nothing rubs. Stop riding if the guard shifts, catches debris, or contacts the tire.