On a bicycle, the shock absorber regulates the rear suspension. It interacts with the suspension fork to absorb bumps and return them in a controlled manner. Without damping, the wheel would continue to oscillate unsettlingly after an impact.
The most important facts at a glance: Bicycle shock absorbers
On a bicycle (mountain bike, full-suspension), the shock absorber is the central component of the rear suspension. It controls the compression and rebound of the bike, increases traction and comfort, and is available as an air shock or with a steel spring.
Stroke and installation length are crucial for the fit in the frame and the travel. Which one you need depends on the intended use. From cross-country to downhill – we'll give you an overview of which rear shock absorber suits which riding style.
Bicycle shock absorbers as part of MTB suspension
Mountain bike suspension consists of one or two parts:
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Fully (Full-Suspension): The suspension consists of a suspension fork (absorbs energy) and a shock absorber (controls the return). The shock absorber regulates the speed of compression and rebound. This system influences the riding feel, traction, and pedaling efficiency.
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Hardtail: The suspension is exclusively provided by the suspension fork at the front, while the rear triangle remains rigid. Bumps are absorbed directly at the rear by the frame, tires, and riding technique – hardtails do not have a shock absorber.
A well-tuned shock absorber on a full-suspension bike minimizes vibrations for the rider in the saddle, thus providing comfort and grip.
Stroke and installation length explained
Stroke refers to the maximum travel of the shock absorber. More stroke means more reserves on rough trails. The installation length is the total length of the shock absorber in an uncompressed state. It must precisely match the frame. Models that are too short or too long will alter the geometry and function and can cause damage to your material.
Types of bicycle shock absorbers
MTB shock absorbers are divided into air and coil models:
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Air shocks: Lightweight, precisely adjustable via air pressure, ideal for variable applications.
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Coil/steel spring shocks: Consistent spring curve, very sensitive to small bumps, perfect for long descents.
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Reservoir shocks: With external oil reservoir, for demanding applications such as enduro or downhill.
Areas of application at a glance
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Cross-Country: Short travel (80–120 mm), mostly air shocks for low weight.
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Trail/All-Mountain: Medium travel (120–150 mm), air or coil depending on preference.
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Enduro/Downhill: Long travel (150 mm+), robust construction, often coil or high-volume air shocks.
Important settings
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Compression: Regulates how quickly the shock absorber reacts upon compression.
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Rebound: Controls the speed of extension.
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High-/Low-speed damping: Separate adjustment for small bumps and hard impacts.
Settings on the shock absorber are usually made via the rotary knob or lever directly on the housing. Compression and rebound can be adjusted incrementally or steplessly, usually with clearly labeled adjustment rings.
Note that for the basic tuning of the air shock via air pressure, you need a special shock pump. Always change the air pressure gradually so that you can clearly understand the effect on riding behavior.
Frequently asked questions
We answer the most common questions about bicycle shock absorbers. Find more information on bicycle suspension in general or on steel springs and remote controls.
What does a bicycle shock absorber do?
It controls suspension movement, improves traction, protects the rider and frame, and provides more control.
What is a shock absorber bushing?
A shock absorber bushing is a small, precisely fitting component that securely mounts the shock absorber in the frame. It serves as a connection between the eye of the shock absorber and the mounting bolt on the frame. Shock absorber bushings ensure play-free movement and protect the shock absorber from lateral forces. Depending on the frame and shock absorber model, there are different sizes and designs.
How much PSI should be in a bicycle shock absorber?
The air pressure depends on the rider's weight and desired Suspension Adjusted Geometry (SAG). It is usually set so that 25–30% of the travel is used while standing. A shock pump and manufacturer's specifications are mandatory.
What are the disadvantages of bicycle suspension?
Increased weight, increased maintenance, and potential efficiency losses when climbing. However, with proper tuning, the advantages usually outweigh the disadvantages.
What is the difference between suspension and damping?
Suspension stores energy (spring or air chamber). Damping regulates the return of this energy via oil or valves.
Which shock absorber should I use for my bike?
Orient yourself according to frame specifications, desired travel, riding style, and weight. For XC often air, for Enduro often coil or high-volume air.
Conclusion: Tune the shock absorber to your area of use
Choose a shock absorber suitable for stroke, installation length, and application. Air for weight and adjustability, coil for consistency and comfort. Adjusting compression and rebound makes all the difference. On raaad.de you will find a large selection of different shock absorbers – from air shocks for light XC bikes to robust coil shocks for downhill MTBs.
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