The Fiend Belmont PC features a 4.25ââ¬Â long, durable, replaceable nylon outer sleeve with a 40mm OD sleeve that reduces dropout drag, the 4mm wall thickness provides extended grind life. A 6000 series aluminium core keeps the weight to a minimum and has a 14mm axle bore, 3/8ââ¬Â adaptor included. Replacement sleeves sold separately.