Softail Slim

2021 Harley-Davidson Softail Slim Technical Analysis & Specification Breakdown

At the heart of the 2021 Harley-Davidson Softail Slim custom - cruiser motorcycle, Harley-Davidson pairs a 1746 cc (106.5 cu in) air-cooled v2, four-stroke architecture with road-focused gearing. In factory specification, peak output is rated at 86 HP (62.8 kW) at 5,020 rpm while maximum torque reaches 149.2 Nm (110 lb-ft) at 3,000 rpm, transferring power to the rear wheel through a 6-speed gearbox and belt final drive. With a specific output of 49.3 HP per liter and a 2,020 rpm working window between peak torque (3,000 rpm) and peak power (5,020 rpm), the engine character is prioritizing low-RPM tractability, mechanical longevity and relaxed throttle response over peak redline numbers.

On the scales, the Softail Slim measures 304.4 kg (671 lbs) wet (curb), translating to a power-to-weight ratio of 0.28 HP/kg (3.54 kg per horsepower). Rider ergonomics and chassis geometry center around a 648 mm (25.5 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops, combined with a 1,630 mm (64.2 in) wheelbase engineered for planted straight-line stability. The 18.9-liter (5 US gal) fuel tank paired with a rated consumption of 5 L/100 km provides an estimated theoretical range of roughly 378 km (235 miles) between fill-ups.

Within MotoLibrary's Harley-Davidson archive, this model family spans 9 indexed model years from 2013 to 2021, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.