It’s post WWII-Era bobber styling on a modern power-cruiser

LISTEN 10:30

Harley-Davidson and the custom-bike culture have always gone hand-in-hand, and the updated-in-2018 Softail Slim makes for a rolling tribute to both. The Slim rides on the same, newly-revamped frame as the rest of the fake-hardtail family for the unmistakable geometry and dated look that you just can’t get from a traditional swingarm. Bobbed fenders and blackout paint tie right into the custom trends of yesteryear quite nicely, but it’s the 107 cubic-inch Milwaukee-Eight V-Twin and its 100-plus pounds of torque that drives the Slim past “historical-tribute” turf right into viable power-cruiser territory. Since the whole point of the original bobbers was to provide a more thrilling ride, I find this pairing of power and panache to be entirely fitting.

  • 2018 - 2021 Harley-Davidson Softail Slim
  • Year:
    2018- 2021
  • Make:
  • Model:
  • Engine:
    V-Twin
  • Displacement:
    107 cubic inches
  • Top Speed:
    125 mph (Est.)
  • Price:
    15999
  • Price:

Harley-Davidson Softail Slim Design

  • Vintage H-D styling
  • Low-slung tuck-n-roll solo saddle
  • LED lighting
2018 - 2021 Harley-Davidson Softail Slim
- image 970777
2018 - 2021 Harley-Davidson Softail Slim
- image 970778

It was a big year for the Softails when the MoCo phased out its Dyna cruisers and the Softail family took on the full weight of the cruiser market all by its onesies, and it was interesting to see what the factory decided to hinge its mid-size hopes upon.

Okay folks, time for a history lesson. You see, back in the day Harley used the old rigid-style frame for its FL models, but in ’49, a new bit of fandanglery known as the hydraulically-damped telescopic shock found its way onto the front end, and it would be almost a decade before the shock-and-swingarm would see the light of day. It is this time period that Harley targets with its Softail Slim.

Fat front forks are made to look even fatter with classic fork skirts that come in blackout to match the fork sliders, headlight can, handlebar, instrument panel (hooray!), jugs, breather cover, and rear fender struts. Both front and rear fenders come heavily bobbed so that the front is close to the effective minimum size and the rear has just a few inches of reveal past the struts, just like the old-school bobbers. The blackout trim and polished-aluminum tripletree is an unusual arrangement, and I can’t say I’m a fan of the naked headlight though I understand that it looks more bobberish that way, but I think a blackout nacelle would look sweet.

Black rims set off the polished spokes just as the black jugs accentuate the polished nosecone and rocker boxes for nice contrast all around. Seat height is slung way low at 25.5-inches off the ground, so not only is the center of gravity low, but it’s a short trip from ground to hip so it should land in flat-foot territory for all: great for leverage, comfort, and confidence at stops.

The solo saddle comes with a classy, tuck-and-roll finish that looks really cool, but will have you digging in the accessories catalog right off the bat if you plan on sharing your adventures with a friend. A side-mount plateholder helps keep the rear end clean to fit in with the rest of the bike for an overall low, clean, and custom look.

Harley-Davidson Softail Slim Chassis

  • Lightweight frame with classic Softail lines
  • Race-style cartridge forks
  • Hard-tail look
  • More agile handling and eager in the corners
2018 - 2021 Harley-Davidson Softail Slim
- image 970780
2018 - 2021 Harley-Davidson Softail Slim
- image 763899
2018 - 2021 Harley-Davidson Softail Slim
- image 763898

It’s the frame — or more specifically, the swingarm — that really makes the look work on the Softail Slim. Harley took its Softail frame that had remained more-or-less unchanged since its inception in 1984 and gave it a complete redesign in 2018. Half of the frame members hit the shop floor. What remains is stiffer and much lighter than before with the same faux-rigid swingarm that articulates with an under-seat shock to soften the jolts.

The rear shock is limited to a preload adjustment and though the front end is non-adjustable, it isn’t quite pure vanilla thanks to the Dual Bending Valve technology from Showa that delivers a superior ride via demand-driven damping. While that’s an improvement, it’s still far behind the curve.

Fat, 16-inch hoops round out the rolling chassis with a 130/90 up front, a 150/80 out back, and the whitewalls mounted on the inside. A four-piston anchor grabs the single front disc with a twin-pot caliper in back. You can have ABS if you want it, but it will set you back another eight Benjamins.

Overall, the chassis is rather simple compared to some of the alternatives in the current market, but the ride quality belies that simplicity. The Softail family has never been know for its agility — quite the opposite in fact — but the factory rectified a multitude of sins with this redesign and the new generation is quite a bit more eager in the corners and easier to handle, relatively speaking since the steering head measures out at 30 degrees of rake with 5.8 inches of trail which lends it a fairly stable nature, so do try and keep it in perspective.

Frame: Mild steel, tubular frame; rectangular section backbone; stamped, cast, and forged junctions; MIG welded; aluminum forged fender supports
Swingarm: Mild steel, tubular sections, stamped x-member, forged axle junctions; MIG welded; removable belt spacer
Front Suspension/Travel: Showa Dual Bending Valve 49 mm telescopic with aluminum fork triple clamps; dual rate spring; “beer can” covers/ 5.1 in. (130 mm)
Rear Suspension/Travel: Hidden, free piston, coil-over monoshock; 43 mm stroke; cam-style preload adjustment/ 3.4 in. (86 mm)
Rake (steering head): 30°
Fork Angle: 30°
Trail: 5.8 in.
Lean Angle, Right/Left: 27.4°/27.4°
Wheels, Front/Rear: 16 in. x 3 in. Gloss Black, Steel Laced
Tire, Front: Dunlop® Harley-Davidson® Series, bias blackwall, D401F 130/90B16,53H,BW
Tire, Rear: Dunlop® Harley-Davidson® Series, bias blackwall, D401T 150/80B1677H,BW
Brakes, Front: 300 mm solid uniform expansion rotor, 4-piston fixed caliper
Brakes, Rear: 292 mm solid uniform expansion rotor, 2-piston floating caliper
ABS: Optional

Harley-Davidson Softail Slim Drivetrain

  • Milwaukee-Eight 107 V-Twin engine
  • 110 lb-ft @ 3,000 rpm
  • Ample roll-on anywhere in the rev range
  • Solid holeshot performance
2018 - 2021 Harley-Davidson Softail Slim
- image 970776
2018 - 2021 Harley-Davidson Softail Slim
- image 970779
2018 - 2021 Harley-Davidson Softail Slim
- image 970775

Of course, the real star of the show on the Softail Slim is the Milwaukee-Eight powerplant, well-established now having proven itself in the FLT/FLH model family. Thankfully, it trickled down to the cruisers to completely replace the much-maligned Twin Cam engine and return to the single-cam drivetrain. Not only does this return the right-side case to a more traditional shape, but it also puts the pushrod geometry back where it belongs.

One thing you will notice right away when you walk up to the bike is just how big the Mil-8 engine really is. I mean, this thing is a real chunk o’ metal, but it would have to be big to accommodate the 1,746 cc displacement. Typically undersquare, it runs a 100 mm bore with a 111 mm stroke, and as you might expect, it brings on the stump-pulling torque early with 110 pound-feet at 3,000 rpm. Solid holeshot performance is backed up with Harley’s strongest roll-on ever— whether in fifth or sixth gear— so you can also have plenty of power reserve for making passes on the interstate.

The air-cooled mill uses a throttle body with electronic fuel injection to manage the induction for a 47 mpg (claimed) fuel efficiency rating, but the 10-to-1 compression ratio will require the stuff from the expensive-fuel pump. As with the suspension, Harley is a bit behind the curve in engine fandanglery. There are no traction control or variable power modes to be had, so there is still room for improvement in that area.

One thing longtime fans notice right away — and complain about in many cases — is the lack of vibration from the Mil-8. A balancer mitigates much of the vibration inherent in 45-degree V-twins, especially ones that run both con-rods on a common throw with an even firing order. The stock pipes dampen the exhaust note to a pleasant purr rather than a full-throated roar, much to the dismay of the purists. Bottom line is, this new generation of bikes definitely has more social value than in the past, and that’s not necessarily a bad thing.

Engine: Milwaukee-Eight® 107
Bore x Stroke: 3.937 in. x 4.374 in.
Displacement: 107 cu in
Compression Ratio: 10.0:1
Engine Torque (J1349): 110 lb-ft @ 3,000 rpm
Fuel System: Electronic Sequential Port Fuel Injection (ESPFI)
Exhaust: 2-into-2 shotgun; catalyst in muffler
Primary Drive: Chain, 34/46 ratio
Gear Ratios (overall): 1st: 9.311, 2nd: 6.454, 3rd: 4.793, 4th: 3.882, 5th: 3.307, 6th: 2.79

Harley-Davidson Softail Slim Pricing

2018 - 2021 Harley-Davidson Softail Slim
- image 970774
2018 - 2021 Harley-Davidson Softail Slim
- image 763897
2018 - 2021 Harley-Davidson Softail Slim
- image 763902

As always, the bottom price tier for the 2021 Softail Slim is occupied by the Vivid Black model that rolls for $15,999. If glossy black ain’t your thing, another four Benjamins will get you a brand new Softail Slim in Billiard Red. For 2021, you have a choice between two two-tone colorways for $16,749. ABS is a $795 option, and the California emissions package will set our West Coast brothers and sisters back another $200.

Model ID: FLSL
Standard Equipment: Security System
Warranty: 24 months, unlimited mileage
Colors:
└ 2018: Vivid Black, Black Denim, Industrial Gray Denim, Wicked Red, Bonneville Salt Denim
└ 2019: Vivid Black, Black Denim, Industrial Gray, Wicked Red, Bonneville Salt Denim, Billiard Blue, Rugged Gold Denim
└ 2020: Vivid Black, Black Denim, Barracuda Silver Denim, Billiard Burgundy
└ 2021: Vivid Black, Billiard Red, River Rock Gray Denim/Black Denim, Midnight Crimson/Stone-Washed White Pearl
Pricing:
└ 2018: Vivid Black: $15,899, Color: $16,299
└ 2019: Vivid Black: $15,949, Color: $16,349
└ 2020: Vivid Black: $15,999, Color: $16,399
└ 2021: Vivid Black: $15,999, Color: $16,399, Two-Tone:: $16,749

Harley-Davidson Softail Slim Competitors

2018 - 2021 Harley-Davidson Softail Slim
- image 763929
2020 Indian Chief Dark Horse
- image 863024

At first I thought the El Dorado from Moto Guzzi would be my huckleberry, but the engine was just too small to go up against the Mil-8 107. I decided that I would stick closer to home and check out the Indian Chief Dark Horse instead.

Indian Motorcycle Chief Dark Horse

2020 Indian Chief Dark Horse
- image 863026

Instead of blackout touches, the aptly named Dark Horse looks like it was dipped in a vat o’ black with just a few shiny bits added after the fact. It achieves a much darker look, but misses that garage-built note that the Slim brings to the table.

The Chief also runs with much fuller fenders that diverge from the bobbed Harley, but to be fair, much of Indian’s brand identity is actually in those full, swept fenders, so it makes sense to leave them as is. As with the Slim, a solo seat will have you at the parts counter before you share the experience with anyone else, but the solo seat works with the overall attitude these two bikes represent.

Indian doubles down on the front brakes with dual, 300 mm discs up front and ABS protection, but the suspension is as vanilla as Harley’s with no advantage to be had by either. Indian’s Thunder Stroke 111 drives the Chief with 119 pound-feet of torque at three grand, not enough to register the difference on the heinie dyno, but a slight edge to Indian. Too bad Indian is (seemingly) as far behind the curve as Harley when it comes to electronic engine-control wizardry, so there is no TC or any such like from either.

The Chief actually tops Harley at the checkout with a $18,499 sticker; more than the expensive paint package plus ABS, and it doesn’t often come to pass that someone comes off prouder than the MoCo at the till.

Read our full review of the Indian Motorcycle Chief Dark Horse.

He Said

“Always been a fan of the Softails, and while I’m loving the rebuild, I find the Slim to be a mixed bag. It definitely looks custom, though not quite in the way I would have done it. The engine selection is a definite win, but I wonder at a lack of a 114-inch model, or some interesting paint packages like two-tones and candies. Oh well, maybe next year.”

She Said

My wife and fellow motorcycle writer, Allyn Hinton, says, “The Softail Slim really draws its styling from the post WWII era when bobbers were all the rage. It’s a style that is seeing a resurgence in popularity. Another touch that lends to the style is the "Hollywood" handlebar with the brace across the top of the bar. The ride is much improved, in my opinion, and it handles really nice. This new frame combined with the Mil-8 engine is worth a look if you checked out a Slim in the past and weren’t impressed. The brakes are much better than I expected. The improvements made to the brakes a couple of years ago reduced the amount of effort at the brake lever and the brakes feel much more positive now even though it’s still a single disc."

Harley-Davidson Softail Slim Specifications

Engine & Drivetrain:
Engine: Milwaukee-Eight® 107
Bore x Stroke: 3.937 in. x 4.374 in.
Displacement: 107 cu in
Compression Ratio: 10.0:1
Engine Torque (J1349): 110 ft-lb @ 3,000 rpm
Fuel System: Electronic Sequential Port Fuel Injection (ESPFI)
Exhaust: 2-into-2 shotgun; catalyst in muffler
Primary Drive: Chain, 34/46 ratio
Gear Ratios (overall): 1st: 9.311, 2nd: 6.454, 3rd: 4.793, 4th: 3.882, 5th: 3.307, 6th: 2.79
Chassis:
Frame: Mild steel, tubular frame; rectangular section backbone; stamped, cast, and forged junctions; MIG welded; aluminum forged fender supports
Swingarm: Mild steel, tubular sections, stamped x-member, forged axle junctions; MIG welded; removable belt spacer
Front Suspension/Travel: Showa Dual Bending Valve 49 mm telescopic with aluminum fork triple clamps; dual rate spring; “beer can” covers/ 5.1 in. (130 mm)
Rear Suspension/Travel: Hidden, free piston, coil-over monoshock; 43 mm stroke; cam-style preload adjustment/ 3.4 in. (86 mm)
Rake (steering head): 30°
Fork Angle: 30°
Trail: 5.8 in.
Lean Angle, Right/Left: 27.4°/27.4°
Wheels, Front/Rear: 16 in. x 3 in. Gloss Black, Steel Laced
Tire, Front: Dunlop® Harley-Davidson® Series, bias blackwall, D401F 130/90B16,53H,BW
Tire, Rear: Dunlop® Harley-Davidson® Series, bias blackwall, D401T 150/80B1677H,BW
Brakes, Front: 300 mm solid uniform expansion rotor, 4-piston fixed caliper
Brakes, Rear: 292 mm solid uniform expansion rotor, 2-piston floating caliper
ABS: Optional
Dimensions & Capacities:
Length: 90.9 in.
Overall Width: 38.2 in.
Overall Height: 43.1 in.
Seat Height, Laden: 25.5 in.
Seat Height, Unladen: 26 in.
Ground Clearance: 4.7 in.
Wheelbase: 64.2 in.
Fuel Capacity: 5 gal.
Fuel Economy: Estimated City/Hwy: 47 mpg
Oil Capacity (w/filter): 5 qt.
Dry Weight: 642 lb.
Curb Weight: 671 lb.
GVWR: 1160 lb.
GAWR, Front/Rear: 450 lb. / 730 lb.
Top Speed: 125 mph (governed)
Electrics:
Lights (as per country regulation), Indicator Lamps: High beam, turn signals, neutral, low oil pressure, engine diagnostics, ABS (optional), security, low battery voltage, low fuel
Gauges: 5-inch analog speedometer with digital gear, odometer, fuel level, clock, trip, range and tachometer indication
Details:
Model ID: FLSL
Standard Equipment: Security System
Warranty: 24 months, unlimited mileage
Colors:
└ 2018: Vivid Black, Black Denim, Industrial Gray Denim, Wicked Red, Bonneville Salt Denim
└ 2019: Vivid Black, Black Denim, Industrial Gray, Wicked Red, Bonneville Salt Denim, Billiard Blue, Rugged Gold Denim
└ 2020: Vivid Black, Black Denim, Barracuda Silver Denim, Billiard Burgundy
└ 2021: Vivid Black, Billiard Red, River Rock Gray Denim/Black Denim, Midnight Crimson/Stone-Washed White Pearl
Pricing:
└ 2018: Vivid Black: $15,899, Color: $16,299
└ 2019: Vivid Black: $15,949, Color: $16,349
└ 2020: Vivid Black: $15,999, Color: $16,399
└ 2021: Vivid Black: $15,999, Color: $16,399, Two-Tone:: $16,749

Further Reading

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TJ Hinton
TJ Hinton
T.J got an early start from his father and other family members who owned and rode motorcycles, and by helping with various mechanical repairs throughout childhood. That planted a seed that grew into a well-rounded appreciation of all things mechanical, and eventually, into a formal education of same. Though primarily a Harley rider, he has an appreciation for all sorts of bikes and doesn't discriminate against any particular brand or region of origin. He currently holds an Associate's degree in applied mechanical science from his time at the M.M.I.  Read full bio
About the author

All images featured on this website are copyrighted to their respective rightful owners. No infringement is intended. Image Source: harley-davidson.com, indianmotorcycle.com

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