Bike suspension adjustment guide

A job that is certainly not easy and rarely talked about. Here are some basic tips to adjust the suspensions in order to get a good set-up in every condition of use. We gain in safety and driving pleasure. Also, you will know how to find best shocks for harley touring.

Before adjusting the suspension, it is essential to tune the operation between the front and rear suspension to minimise the amount of imbalance that rough road surfaces cause the bike to balance. Failure to do so may cause the motorcycle to react abnormally when subjected to external stress, resulting in loss of motorcycle control. In addition to tuning the front suspension with the rear suspension, it is important to harmonize the operation of the shock absorber with the relative spring, avoiding, for example, to preload the spring too little and instead braking the hydraulics too much, obtaining a suspension that sinks too much for any small roughness and then struggling to relax.

Another parameter to take into account is the tyre pressure, which must be that prescribed by the manufacturer. Adjusting the suspension with the wrong tyre pressure is totally useless.

This type of adjustment can be divided into two distinct and separate stages. The first is a static adjustment where you adjust the bike’s ride attitude, i.e. the height of the front and rear end under riding conditions; the second is a dynamic adjustment where you adjust the adjusters to improve the bike’s behavior, for example, when cornering or braking.more

Always remember that in order to achieve effective suspension operation according to the settings of the shock absorber, whether it is the monoshock or the fork, it is important that these components are 100% efficient. Control by a good suspension mechanic is necessary for an overhaul that keeps the working fluids (nitrogen and oil) in the correct state.

Preload adjustment (static sag without rider)

  1. Fully open the brake hydraulics in compression and rebound of both the fork and the single shock absorber.
  2. Lift the wheels completely off the ground, grasping the bike from the frame and not from the suspension components.
  3. With the bike raised, measure the distance between the wheel axle and a fixed point on the frame (a screw for example). The ideal line between the wheel axle and the fixed point must be as perpendicular as possible to the road surface.
  4. Place the wheel on the ground and repeat the measurement illustrated in point 3. The difference between the two measurements is referred to as the static sag of the motorcycle. For medium and maxi sport bikes and for road use, the static sag must be 20-30% at the front and 5-10% at the rear. For track use, the values become 15-20% at the front and 5-10% at the rear.
  5. Repeat the measurement of point 4 limited to the rear with rider on board (sag rider), petrol and any passenger and luggage. Under these conditions, the lowering of the rear end must be 20-30% for road use and 20-25% for track use. Also in this case the measurement must be made taking as reference the one determined in point 3.

Adjusting the hydraulics

  1. To adjust the fork hydraulics, pull the front brake lever.
  2. Compress and extend the fork repeatedly, loading it from the handlebar.
  3. Let the fork extend by removing the load but always keeping the brake lever pulled. The fork must extend completely and then compress slightly. If the fork does not sink after extension, then the compression brake is excessive. If, on the other hand, it should swing for a few moments, then there is too little rebound braking.
  4. To adjust the rebound brake of the single shock absorber, it is necessary to compress it abruptly and let it extend. Full rebound must take about 1.5 sec. Adjust the compression brake as indicated in the owner’s manual.

Dynamic regulation

The dynamic regulation is much more complex than the static one because in this phase also the driving style and the impressions of the driver take over. Purely scientific and theoretical disquisitions must, therefore, give way in part to the driver’s feelings when driving. It is important to make one adjustment at a time, proceeding in small steps, so that you always know in which direction you are going. According to this advice, therefore, it is always advisable to try one register at a time by turning it one or at most two shots for each attempt.

To make this guide easier to use, here are several situations that may occur when the suspension is not adjusted in the best way. It will be easy to locate the case that comes closest to your motorcycle’s behavior and then follow the instructions.

The motorcycle is stiff in a straight line and tends to skip over rough terrain. The preload and compression brake are too high.

The wheels do not copy (follow) the roughness. The spring preload is too high.

The bike tends to sway in fast bends. It is necessary to increase both the preload and the compression brake.

When braking, the bike breaks down excessively at the front and skids with the rear wheel. The fork springs are poorly preloaded and the compression brake is insufficient.

The front end is unpredictable and unsafe in the middle of corners. Rebound braking is excessive or insufficient. Compression brake is excessive.

The bike tends to widen the trajectory. The spring preload of the fork springs is excessive or the spring preload of the monoshock is insufficient, or the rebound brake of the monoshock may be excessive.

The motorcycle tends to close the trajectory and the rear tyre tends to drift. The rear end is too preloaded or there is excessive shock absorber compression brake. The fork is poorly preloaded.

Summing up for a good dynamic adjustment you have to take into account that:

The preload is used to adjust the height of the bike as well as to give a more or less dry operation of the suspension on roughness. Therefore, acting on this parameter changes the behavior of the bike when cornering, which can go from under to oversteer depending on whether you increase the preload of the fork or monoshock. The compression and rebound brakes are used to adjust the speed at which the suspension is compressed or extended. Suspension adjustment is always a compromise between the different situations you may encounter while riding. In fact, an optimal braking setting will not be optimal for driving on a bumpy stretch of road, just as a twisty track setup will be deleterious for fast ones.

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