In this brief article, we will discuss the swingarm Suspension and the types of Swingarm suspension.
What is a Swingarm Suspension?
Swingarm suspension is, as the name suggests, a swinging rear suspension control arm that connects the motorcycle rear wheel to the chassis. The Swingarm is also known by the names “swing fork” or “pivoted fork”.
History Behind the Swingarm Suspension
The early version of a motorcycle was a more strengthened versio of a bicycle with motorised propulsion. The basic setup was the ‘Diamond frame’ bicycle architecture with no rear suspension.
The rear suspension came much later in the evolution of the motorcycle. In the early versions of the rear suspension, many Swingarm types of suspension had been tried out. The Indian’s leaf spring suspended swingarm, and Matchless’s cantilevered coil spring swingarm were among the notable early examples. In the pre-World War II era, the plunger suspension, restrained on 2 vertical posts, became popular.
What are the different Types of SwingArm Suspension?
The Different Types of SwingArm Suspension are:
- Cantilever Swingarm
- Parallelogram Swingarm
- Extended Swingarm
- Double Swingarm
A Cantilever Swingarm is called so because the spring is mounted horizontally. The spring-damper top mount is on the inner side of the chassis and the bottom mount is on a triangular-shaped support welded to the top of the swingarm. Notable examples are the HRD-Vincent, Yamaha and the Matchless.
As the name indicates, the Swingarm, in the side-view, has 2 parallel control arms connected to the chassis and the upper and lower wheel-hub supports. The most important advantage in the Parallelogram swingarm mechanism is that the rear wheels would tend to raise on acceleration, as opposed to a “squat” that is normally seen on conventional swingarm rear suspensions. Another advantage is that the parallelogram mechanism provides a straight vertical path of travel to the rear wheel, rather than along an arc, thus ensuring minimal wheelbase change during acceleration and braking.
Notable examples are the BMW Paralever system found on the 1988 R80GS and the R100GS motorcycles, the 1985 “Magni Le-mans” and the Moto Guzzi “Compact Reactive Drive Shaft system”.
The Extended Swingarm had a swingarm that extended far behind the rear wheel in order to keep the Center of gravity towards the front of the vehicle, since front grip was crucial for stability at high speeds. Normally conventional suspension bikes tend to “wheelie” on take off in a drag race. The extended Swingarm makes the bike planted forward to avoid wheelie’s and loss of frontal grip.
The Single Swingarm that is ‘C-shaped’ and has easy fitment access for the wheel hub from one side. This sort of design is more from the perspective of Formula racing where tire-change time is a crucial factor in the winning races. Compared ti the Double Swingarm, the single swingarm would need to support the same amount of loads and therefore the cross section would nead to be heavy.
The Single swingarm is more seen in high-end motorcycles like the Ducati 1098 superbike in 2007, and it survives in the current Ducati 1199. The Triumph Sprint ST and Speed Triple also feature single-sided swingarms.
The Double Swingarm is probably the most widely seen among all motorcycle rear suspension setups. It has become the rear suspension of choice of all mass-market motorcycle manufacturers due to its simplicity and ease of manufacture.
In this brief article, we have discussed the swingarm Suspension and the types of Swingarm suspension.