Weightone-bike about 2kg, two-bike about 3.5kg, three-bike about 4.6kg. Note1 : The 20 KG weight capacity is for one-bike rack , the two and three bike rack can carry more weight. If the diameter of the fork is 15mm or 20mm. Fork widths of 100mm or 110mm. If the diameter of the fork is 9mm/12mm.We only send one pair of adapters as gift for each order. We sell one pair of adapter as price 5 GBP. If you need an adapter. Please indicate which adapter you need in the order. If there is no note adapter size in the order, we can't give the adapter. Without any harm to the car. Clean up car and sucker. Press cylinder rod until you can't see the white part. Confirm the rear wheel position. Fixed rear wheel and pedal. If you don't know how to install, please go to see item video by computer. If it is installed on a car sunroof, please don't open the skylight. The item "RockBros Suction Bike Carrier Quick Installation Roof Rack For 2 Bikes UK STOCK" is in sale since Saturday, July 27, 2019. This item is in the category "Sporting Goods\Cycling\Car Racks". The seller is "inbike" and is located in Dunstable. This item can be shipped to European Union member countries.