Did You Know | 11 May 2021

Compression And Rebound Damping Adjustment: What Is It And How It Helps

Compression And Rebound Damping Adjustment: What Is It And How It Helps

Most everyday motorcyclists ride their motorcycles in factory settings. This includes the suspension setup because it can turn out to be a little tricky to work with. The standard suspension settings for a new motorcycle are based on an average rider determined by the manufacturer. But if you wish to adjust your motorcycle’s suspension, there are two terms which you often come across – ‘Compression’ and ‘Rebound damping’. Adjusting these two parameters according to your weight, riding style, and other factors could bring a world of difference to your motorcycle’s behaviour and make it a lot more suitable for your riding style. Before we delve deeper into the subject of suspension damping adjustability, remember that the terms compression or rebound damping are not mistaken with another term associated with suspension adjustment, namely preload.

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Setting up preload

Before getting down to adjusting the compression and rebound damping for your motorcycle, you need to get the way around preload. Now, unlike what one might want to think, preload adjustment’s primary purpose is not to make a suspension stiffer or softer. Sure, one might observe a slight change in the stiffness, but changing the preload settings primarily increase or decrease what’s known as the motorcycle’s sag. When the rider is seated, the suspension position to its position when it’s on top of the stroke is called the rider sag. By adjusting preload, one can increase or decrease the rider sag.
With more preload, the motorcycle’s suspension will somewhat rise, and the rider sag will be reduced such that the suspension will require a lot more force or weight to bottom out. On the other hand, reducing preload will make the motorcycle sit relatively lower, closer to the bottom of its suspension travel. The motorcycle suspension would bottom out with lesser weight when the preload is less. Preload adjustment has more to do with the rider and luggage weight, and it is used to prevent the suspension from bottoming out. For example, a heavier rider with luggage might want to increase the preload on his motorcycle, while a lighter rider without any luggage might opt for a lesser preload.

Compression damping

Compression damping, in layman terms, is the rate or speed at which the front or rear suspension of your motorcycle is compressed. It doesn’t have anything to do with the extent or travel of the suspension but the speed with which it is compressed. With all things being equal, a higher value of compression damping would mean that the suspension would compress at a slower rate while going over a bump. On the other hand, a lower value for compression damping would mean the suspension would compress faster over the same bump.
In other words, compression damping is the suspension’s resistance to allow your motorcycle’s wheel to move upward in the stroke while absorbing a bump. If the compression damping is too high, the fork or the rear shock cannot compress quickly enough to absorb the bump and hence, the impact is transferred into the chassis, resulting in a rather stiff ride.
If the compression damping is too soft, even rapid deceleration or braking can result in compressing the motorcycle’s suspension. Lower compression value might result in a plusher ride, but it also increases the risk of the suspension bottoming out.
While adjusting the compression damping, as one would imagine, the goal is to find the right balance for a rider - the sweet spot between a reasonably absorbent ride and a taut, predictable handling setup.

Rebound damping

Rebound damping is the rate at which the suspension can extend and return to its normal position once the motorcycle has encountered a bump and the compression part is over. A lower value of rebound damping would allow the suspension to expand and the wheel to reach back to the surface quickly. Conversely, a higher rebound damping value would increase when the suspension expands back, and the tyres find contact with the tar.
Rebound should happen in a controlled and smooth motion to find the perfect balance. The motorcycle will start handling poorly if the reaction is too slow or the movement is too rapid. Too much rebound damping will prevent the wheel from gaining traction again after encountering a bump because it will keep the suspension compressed when it should be extending to follow the road. On the other hand, the motorcycle will have a wobbly feeling if there’s too little rebound damping, causing the suspension to extend fast enough to push the motorcycle up forcibly.
As mentioned before, the key to finding the perfect setting is to experiment and ride extensively until you discover the rebound damping setting that suits your riding environment and style the best.

Some general guidelines

While it’s impossible to define what an ideal compression or rebound damping set-up should be as it varies for different riders, motorcycles and riding conditions, here is some basic knowledge to get you started.

While adjusting the dampers for the front suspension, twist the adjusters gently and never push them beyond their operating range, as it may cause damage to the vehicle’s internal components. In the end, there is no magic formula that works for all riders and surfaces alike. Depending on the kind of dynamic behaviour or ride quality you want from your motorcycle, you will have to experiment with adjusting the compression damping of your motorcycle’s suspension and settling on a setting that suits you well.

If you feel that the front forks dive a little too quickly when you brake or go over a bump, it is advisable to increase the compression damping. On the other hand, if you think that the front could do with more movement, reduce the compression damping. To make the whole process a lot easier, manufacturers tend to use plus and minus signs on the adjuster to help you understand it a little better.

If the motorcycle feels wobbly, it is time to adjust the rebound and increase the damping. If it is too stiff and skittish, one should reduce the rebound damping in steps to bring the right amount of absorbency to the ride.

The ultimate goal is to achieve maximum comfort, confidence and control. The best way to find out how the adjustments have altered the whole experience is simple – go ride!
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