:Seat post diameter require should be between 27.2MM（1.07"）-31.8MM（1.25"），and Seat posts require at least 2 inches high of mounting space. As there is no extra support leg on both sides, this rack is not suitable for carrying heavy goods or large pack travel, its biggest feature is light and convenient;At last,Kids' bike、foldable bike、bike tire size below 24 in、square bike seatpost tube can not be used.

【High Quality Materials rack and bag】:This carrier rack is made of durable TIG-welded, heat-treated, corrosion-resistance anodized aluminum,one-body main Thickened Main Tube（Pipe diameter 32MM and thickness 2MM

【Installation or Removal quickly】:Thanks to the quick release clamp, only one step is needed to attach the bike rack to your bicycle or take it off.