Softail Fat Boy

2015 Harley-Davidson Softail Fat Boy Technical Analysis & Specification Breakdown

Positioned in Harley-Davidson's custom - cruiser motorcycle lineup, the 2015 Harley-Davidson Softail Fat Boy utilizes a 1690 cc (103.1 cu in) air-cooled v2, four-stroke layout. In factory specification, peak output is rated at 77.8 HP (56.8 kW) at 5,250 rpm while maximum torque reaches 132 Nm (97.4 lb-ft) at 3,250 rpm, transferring power to the rear wheel through a 6-speed gearbox and belt final drive. With a specific output of 46 HP per liter and a 2,000 rpm working window between peak torque (3,250 rpm) and peak power (5,250 rpm), the engine character is prioritizing low-RPM tractability, mechanical longevity and relaxed throttle response over peak redline numbers.

On the scales, the Softail Fat Boy measures 330.2 kg (728 lbs) wet (curb), translating to a power-to-weight ratio of 0.24 HP/kg (4.24 kg per horsepower). Rider ergonomics and chassis geometry center around a 635 mm (25 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops, combined with a 1,638 mm (64.5 in) wheelbase engineered for planted straight-line stability. The 18.93-liter (5 US gal) fuel tank paired with a rated consumption of 5.6 L/100 km provides an estimated theoretical range of roughly 338 km (210 miles) between fill-ups.

Within MotoLibrary's Harley-Davidson archive, this model family spans 8 indexed model years from 1998 to 2019, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.