What if our body would not have a skeleton? The body would not have existed. It would be the same case with a motorcycle. A motorcycle would not exist without having a frame (or chassis). It is a structure that holds all the other components of a bike at their respective places. It is one of the most unnoticed and uncelebrated parts of a bike but one of the most critical parts. The design of frames has evolved a lot from its inception. Let us look at the types of the frames available today.
- Backbone frame
As the name suggests, a backbone frame has a long and large diameter tube running along the body, from the steering head to tail. This is one of the most basic frames available in the market. The pros of this frame are it can be easily covered up by the other parts and the body of a motorcycle, simple construction, and low cost. The cons of having this frame in a bike are that it brings down the ability of a bike of being agile, sportier and powerful.
- Perimeter frame
The perimeter frame is one of the costliest of the frames available in the market today. The perimeter frame is also famous for providing an outstanding handling to a bike. The main characteristic of a perimeter frame is that it is made from a single piece of metal. Yes, you read that right! This frame is made from a pressed metal sheet, which gives strength and rigidity to the vehicle. The distance between the steering head and the swingarm is very short, while the frame holds the engine. The short distance between the steering head and the swingarm reduces torsion and flexure in the frame. This frame is preferred by most of the racing bikes.
- Diamond frame
Diamond frame is one of the oldest frames available today. It is a basically a bicycle frame modified to fit into a bike and have a triangular diamond-shaped structure. The down tube of the frame is attached to the steering head at one end and the engine at the other end. The engine thus acts as a stressed member of the frame, which increases the stability of the frame. These frames are used mostly in commuter bikes due to its high strength and stability. The bikes having diamond frames can handle bad roads easily. This frame disappoints in terms of racing assistance and power handling.
- Cradle Frame
Cradle frame is similar to the diamond frame but in the cradle frame engine does not act as a stressed member. A long tube is attached to the down tube that runs below the engine, acting as a cradle for the engine. Cradle frames are meant to absorb a lot of jerks and are used mostly in off-road bikes.
- Trellis frame
Trellis frame has many short metal tubes that are welded together to form multiple triangular structures which in turn form a cage-like structure. The engine is fixed to the structure and acts like a stressed member. This frame is lighter and has a sportier advantage over others. The structure is complex and needs proper customization. Cost is also on the higher side.
6. Monocoque Frame
Monocoque frames are famous in MotoGP bikes and were first constructed by Kawasaki in 1980s. This frame is unique from all the other frames. The bike having monocoque does not have a separate bodywork; the frame acts as the body of the motorcycle. The frame runs across almost every part of the body where the mounting of other components is necessary. It is made up of metal sheets and engine also acts as a stressed member. This frame gives a bike a sportier advantage over other bikes. These frames are heavy and costly thus not suited for a road bike.
The days are not far when we might come across a frameless bike without compromising on any benefits.