Extra 20% off: Serfas SI4 Bike Computer $16 at REI Outlet Get the Serfas SI4 Bike Computer for only $45 – $25 instant savings – 20% site-wide sale = $16 at REI Outlet. Designed for monitoring cycling performance, this bike computer features a large, easy-to-read display. It features a pace arrow that indicates whether you are riding above or below your average speed, programmable odometer, trip distance indicator, elapsed trip time, stop watch, text display, and 12 or 24-hour clock. This small