Of course, here is a full article about the 2018–2021 Harley-Davidson Softail Slim, written in the requested style.
The 2018–2021 Harley-Davidson Softail Slim (FLSL) is a cruiser motorcycle known for its minimalist, post-war “bobber” styling. As a member of the Softail family, it combines the clean, rigid-frame appearance of vintage hardtail motorcycles with the comfort of modern rear suspension. The FLSL model designation places it within Harley-Davidson’s Softail lineup, featuring the Milwaukee-Eight V-twin engine. This generation represents a significant technological and performance leap from its predecessors, marking a complete reinvention of the Softail platform.
Development and Redesign
The 2018 model year marked the most substantial redesign in the Softail’s history, including the Softail Slim. Harley-Davidson retired its Dyna platform and consolidated its big-twin cruiser lineup into a single, all-new Softail chassis. This move was aimed at modernizing the ride and handling characteristics while retaining the classic aesthetic the brand is known for.
Compared to the previous Twin Cam-powered Softail Slim (pre-2018), the new generation introduced several key differences:
Chassis: The new frame is significantly stiffer and lighter than the one it replaced. Harley-Davidson claimed a 34% increase in chassis stiffness, which contributes to more precise handling and improved rider feedback. The overall motorcycle is approximately 35 pounds (16 kg) lighter than the previous model.
Suspension: The traditional twin under-engine shock absorbers were replaced with a single, easily adjustable coil-over monoshock tucked beneath the seat. This new design preserves the “hardtail” look while offering superior damping performance and ride quality. The front suspension was also upgraded to a Showa Dual Bending Valve (SDBV) fork, providing more responsive, linear damping characteristics similar to those found in cartridge-style forks.
Engine: The air-cooled Twin Cam engine was replaced by the Milwaukee-Eight 107 V-twin. This newer engine features four valves per cylinder, dual counter-balancers to reduce vibration at idle, and improved heat management, resulting in a smoother, more powerful, and comfortable ride.
Engine and Performance
At the heart of the 2018-2021 Softail Slim is the Milwaukee-Eight 107 engine. The “107” refers to its displacement in cubic inches (1746 cc). This 45-degree V-twin engine is air- and oil-cooled and was engineered to deliver more torque at lower RPMs, enhancing the riding experience for city cruising and highway passing.
The dual internal counter-balancers make the engine exceptionally smooth, particularly at idle and low speeds, yet allow for a degree of feedback at higher RPMs to retain the signature Harley-Davidson feel. The engine is mated to a six-speed Cruise Drive transmission, which provides smooth shifting and relaxed highway cruising. Power is delivered to the rear wheel via a low-maintenance belt drive system.
Design and Styling of the Harley-Davidson Softail Slim
The Softail Slim’s design ethos is rooted in the custom bobbers that emerged after World War II. These bikes were stripped of any parts deemed unnecessary to reduce weight and create a minimalist look. The FLSL model carries this tradition forward with several distinct styling cues:
Hollywood Handlebar: A wide, braced handlebar that provides a commanding yet comfortable riding position.
Minimalist Fenders: Both the front and rear fenders are “chopped” or shortened, exposing more of the tires.
Solo Seat: A low-slung solo saddle enhances the bobber aesthetic and contributes to the bike’s low 26-inch (660 mm) seat height, making it accessible to a wide range of riders.
Laced Wheels: Classic wire-spoked wheels with blacked-out rims add to the vintage appeal.
Blacked-Out Finishes: Much of the motorcycle, including the engine covers, fork lowers, and “cat’s eye” console, features gloss and satin black finishes, contrasting with the polished cooling fin edges on the engine cylinders.
Modern Lighting:** Despite its retro styling, the Softail Slim features modern technology, including a signature LED “Daymaker” headlamp for improved visibility.
The combination of its low profile, solo seat, floorboards instead of footpegs, and wide handlebar gives the Softail Slim a unique and recognizable presence within the cruiser market.
Specifications Table
| General | |
| Brand | Harley-Davidson |
| Model | Softail |
| Model Class | Softail Slim (FLSL) |
| Model Year | 2018–2021 |
| Type | Cruiser / Bobber |
| Gross Vehicle Weight Rating | 1160 lb. (526 kg) |
| Maximum passengers | 1 (2 with optional passenger seat) |
| Performance | |
| Max. power | Approx. 82-86 hp (Not officially published by manufacturer) |
| Max. torque | 110 ft-lb (149 N•m) / 3000 RPM |
| Lean Angle, Right | 27.4 degrees |
| Lean Angle, Left | 27.4 degrees |
| Size | |
| Length | 90.9 in. (2310 mm) |
| Width | 37.6 in. (955 mm) |
| Height | 43.1 in. (1095 mm) |
| Wheelbase | 64.2 in. (1630 mm) |
| Seat height (laden) | 25.5 in. (648 mm) |
| Ground clearance | 4.9 in. (125 mm) |
| Curb weight | 671 lb. (304 kg) |
| Engine | |
| Type | Milwaukee-Eight 107, 45° V-Twin, Air- & Oil-Cooled |
| Displacement | 107 cu in (1746 cc) |
| Bore × Stroke | 3.937 in. × 4.374 in. (100 mm × 111.1 mm) |
| Compression ratio | 10.0:1 |
| Starting system | Electric starter |
| Fuel supplying system | Electronic Sequential Port Fuel Injection (ESPFI) |
| Ignition control system | Electronic |
| Lubricating system | Dry Sump |
| Oil capacity (with filter) | 5 qt (4.7 L) |
| Engine oil type | SAE 20W-50 Harley-Davidson H-D 360 Motorcycle Oil |
| Transmission | |
| Transmission type | 6-speed Cruise Drive, manual |
| Clutch type | Wet, multi-disc, manual |
| Driving system | Belt drive |
| Primary reduction ratio | 1.353 |
| Final reduction ratio | 2.063 |
| Gear ratio | 1st: 9.311; 2nd: 6.454; 3rd: 4.793; 4th: 3.882; 5th: 3.307; 6th: 2.790 |
| Chassis | |
| Tire size | Front: 130/90B16; Rear: 150/80B16 |
| Rim size | Front: 16 in. x 3 in.; Rear: 16 in. x 3 in. |
| Capacity of fuel tank | 5.0 gal (18.9 L) |
| Fuel consumption | 47 mpg (5.0 L / 100 km) |
| Electric | |
| Battery | 12V, sealed, maintenance-free |
| Headlight | Daymaker Signature LED Headlamp |
| Turning light | Incandescent Bulb |
Tail light
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