Variable bar back Ø 28 mm handlebars with offsetSilver. BMW F 850 GS Adv (17 ), F 900 GS (23 ). Bar back Variable with offset The bar riser made of high quality aluminum alloy moves the handlebars up by 28 mm and, depending on the setting, in 5 mm increments closer to the rider. The bar riser ensures noticeably more comfort when driving, because you can bring the handlebars closer to your own height for a more comfortable and upright sitting position. You have the choice between seven different