It is one of Harley-Davidson's best selling models and has appeared prominently in a number of TV shows and movies. Harley-Davidson also produced a 30th Anniversary edition for 2020. įor 2020, the Fat Boy is only available with the Milwaukee-Eight 114 engine. Further upgrades include an LED headlight and 18-inch "Lakester" rims, with wider 160mm front and 240mm rear tires. Harley-Davidson claims the 2018 chassis is stiffer and lighter than earlier Softail and Dyna platforms.
So as to provide a more comfortable and better controlled ride with improved handling, the front forks contain a Showa "Dual Bending Valve" (SDBV), a cartridge simulator using two valves to control compression and rebound damping, giving linear damping characteristics proportional to fork stroke speed. The 2018 Softail frame has a modified swingarm with a Showa rear monoshock suspension mounted beneath the seat, replacing earlier twin shocks. The 2018 Fat Boys have a redesigned softail frame with Showa front and rear suspension and new twin-counterbalanced Milwaukee-Eight engines.In 2012 the Fat Boy received the new 1,690 cc (103 cu in) Twin Cam engine along with the rest of the softail range.The 2010 "Fat Boy Lo" FLSTFB had the lowest ever Harley seat height.In 2007 the displacement was increased to 1,584 cc (96.7 cu in) and the transmission changed six speeds.In 2005 a 15th Anniversary version was sold with a "Screamin' Eagle" engine, special paint and custom wheels.
The Fat Boy's frame is derived from the 1984 "Softail" which appears to have a rigid hardtail chassis but which in fact has a swinging arm with concealed springs that was originally designed in a Missouri garage in the 1970's by a mechanical engineer named Bill Davis and later Patented in 1976.