Aprilia Sport City One 50 2T (08-11) RMS HD Small End Bearing 12x17x15mm. Aprilia SR50 Racing RMS HD Small End Bearing 12x17x15mm 2003-. RMS Heavy Duty Small End Bearing - 12x17x15mm. Racing Planet UK specialise in scooter parts and small capacity motorcycle parts, with everything from electrical parts, braking, cables and mirrors to engine, transmission, exhausts and accessories.