The Steadyrack Fender rack works by sliding between the fender/mudguard and tyre when rolling the bike onto the rack. If the stays (steel arms connecting the fender to the bike frame) are very close to the tyre or rigid with no flexibility there may not be room to fit the rack arms between and you will not be able to mount the bike in the rack. We recommend a minimum 2cm / 3/4 inch clearance between the tyre and stays to enable the rack to flex and fit between.