Softail

A softail (shortened form of soft tail) motorcycle intentionally looks like vintage motorcycles with a rigid hard-tail frame that has a triangle of steel tubes at the rear axle, as on a bicycle frame, but on a Softail these tubes are actually a triangular swingarm, with the shock absorber(s) hidden, as opposed to clearly visible regular twin shocks on both sides of the rear wheel on standard bikes.

In the 1950s and 1960s, customized motorcycles appeared, many of them based on old Harleys, like surplus US Army Harley-Davidson WLA, or other brands, and often with hard tail frames rather than suspended ones.

As seen in the movie, these hard tails were not easy to ride on bad roads and could be painful if sat on over bumps such as railway crossings.

In 1970, Harley only had the big twin full-dresser touring bike, the FLH Electra Glide, and the small XL Sportster.

His first design, which he worked on in 1974 and 1975, had a cantilever swingarm like on vintage Vincent Motorcycles that pivoted at the bottom and sprung at the top with the springs and shock absorber hidden under the seat.

Haubert built a prototype using his own rear suspension design that closely followed the look of the earlier Harley rigid frames.

Davis attempted to produce the new design independently as the Road Worx Sub-Shock, but the partnership he had put together for this purpose collapsed.

In addition, Harley had just completed the "buy back" from AMF, and had developed the all-aluminium Harley-Davidson Evolution engine that was more reliable that the Shovelhead, and had heads that looked like square versions of the round Panheads.

With the exception of the Deuce, which has a 2 in (51 mm) longer tank, these motorcycles have the same engines, transmissions, and frames, differing mainly in the fork, wheels, and accessories.

[10] In 2017, Harley unveiled a completely redesigned Softail frame for the 2018 model year, the first major change since the introduction of the Twin Cam engine in 2000.

The 2018 Softail frame uses a differently shaped swingarm suspended by a single rear shock absorber, mounted underneath the seat in a similar fashion to the original Haubert and Davis designs.

Many aftermarket manufacturers around the globe have specialized in Softail parts & accessories like wheels, fenders or tanks to change the look of the custom motorcycle.

Three Harley-Davidsons , built about 50 years apart: unpainted 1950s Hydra Glide with clearly visible black hard-tail frame, next to a modern Softail Crossbones that copies the old frame design, the suspended seat, and even the oil tank in black. To the right a black Sportster with twin shocks
Harley Hydra Glide converted to a chopper as seen in the 1969 film Easy Rider , with 1950s hard-tail frame painted red
Harley-Davidson Heritage Softail with chrome swingarm shaped like a triangle
Rear suspension on a Vincent with shocks visible under the seat, introduced in late 1920s
Yamaha XT250 introduced in 1979, cantilever swingarm with central shock hidden under the seat
Harley-Davidson Wide Glide with regular swingarm, twin shocks and square battery box, as introduced in the 1957 Duo Glide
Harley-Davidson Softail with triangular swingarm, shocks under the gearbox, chrome horseshoe oil tank, as introduced in 1983