For 2006 Yamaha R1, the swingarm was extended by 20 millimetres (0.79 in) to reduce acceleration instability. In this year, Yamaha also released a limited edition version in original Yamaha R1 racing colors to celebrates its 50th anniversary. The model (LE/SP) featured a Kenny Roberts replica paint pattern with yellow and black paint, and front and rear custom Öhlins suspension units developed by the same team as the YZR-M1 MotoGP bike. Custom forged aluminum Marchesini wheels specifically designed for the LE shaved nearly a pound off the unsprung weight. A back torque-limiting slipper clutch, and an integrated lap timer rounded out the package, making the LE virtually a production racer. Only 500 units were made for the United States.