The terminology used to talk about motorcycle suspension systems can sometimes be a little confusing, creating misunderstandings and resulting in work which is not 100% accurate.
In this article we aim to create a suspension glossary, explaining the main technical terms used to talk about it.
Keep reading to find out more!
Talking about Motorcycle Suspension Correctly
Motorcycle suspension represents, both in practical and linguistic terms, an area which requires particular precision.
For a sector professional, it is essential to know the technical characteristics of this fundamental motorcycle component and, at the same time, be able to talk about it and describe any issues using the correct terms.
So let's take a closer look together at the most commonly used terminology in the field of suspension.
Spring Rate
This term refers to the compression of the spring, the central component for damping shocks in a high-performance manner and keeping the wheels firmly adhered to the terrain, despite the presence of potholes or slight differences in level.
This value, measured in kg/mm, defines the amount of force necessary to compress the spring a certain distance.
For this reason, in order to obtain an accurate calibration of the vehicle, it is important to also take the rider's weight into account when carrying out these operations.
The spring should be soft enough to perform its damping function, while at the same time sufficiently rigid to guarantee stability, above all during braking and acceleration.
Spring Preload
This is a procedure which involves slightly compressing the spring in advance, starting from its free length with the suspension components fully extended.
This compression will affect the force necessary to further compress the spring during movement
It is important to highlight that, unlike what you might expect, the preload has no effect on the hardness of the spring.
Sag
This is the measurement of how much the suspension can compress starting from the fully extended position.
It is possible to identify two types of sag:
- Free sag: when the suspension compresses under the weight of the motorcycle
- Rider sag: when the suspension compresses under the weight of the bike with the fully equipped rider in the saddle
This measurement allows us to identify how much the suspension will be able to further extend during movement of the vehicle, for example when it goes over a pothole.
The optimum sag values are as follows:
- Rider sag: ¼ of the compression of the spring
- Free sag: ⅓ of the rider sag
In order to ensure optimum bike performance, it is recommended to attain these values with the minimum possible preload.
Damping
This is the reduction of the amplitude of the mechanical oscillation.
It allows us to regulate the speed at which a suspension component compresses or expands thanks to the presence of oil in the shock absorbers which is driven through small openings such as holes during compression or extension of the component.
The difficulty with which the oil passes through the openings creates a resistance which allows the movement of the suspension to be controlled.
The quality of the shock absorbers is important in order to keep the elasticity of the spring under control, which is crucial for traction, comfort and control of the bike.
Compression and Rebound
The compression is the damping force which is created when the motorcycle suspension is compressed, while rebound is that generated when the suspension extends following the compression.
There are also some useful adjectives to refer to motorcycle suspension:
- Fast/slow: this does not refer to the speed of the bike itself, but rather the speed at which the suspension moves, the damping speed
- Hard/soft: refers to the feeling of the suspension during the ride, and can be used both when talking about damping and springs
We have clarified some key motorcycle suspension terminology.
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