This is how it works: Adjust the spring base yourself

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This is how it works: Adjust the spring base yourself

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This is how it works: Adjust the spring base yourself

This is how it works: Adjust the spring base
Adjust the spring base yourself

How do I set up my chassis correctly? Motorcycle chassis often offer a variety of adjustment options. Before the experiments with the damping adjustment, the spring base must be correct. 2Rader shows how it’s done.

Manuel Fuchs

04/24/2012

The right spring base


This is how it works: Adjust the spring base yourself

Triumph Speed ​​Triple.

“How do I properly tune my suspension??” Before you dive into the depths of rebound and compression damping, make sure you have the right spring base. The rule of thumb is:

When stationary, a motorcycle without a driver sinks in front by a quarter of the total suspension travel and in the rear by a tenth. With the rider, the motorcycle should deflect by a third at the front and a quarter at the rear. How do you do that?


This is how it works: Adjust the spring base yourself

Fasten the cable tie to the immersion tube, rebound completely and note the measured value.

First step:

Rebound the motorcycle so far that the front wheel is no longer in contact with the ground.

If the main stand or front jack is not available, a second person can tip the motorcycle over the side stand.


This is how it works: Adjust the spring base yourself

Park the motorcycle without a rider, measure the distance from the cable tie to the fork base.

Second step:

Measure the visible length of the fork inner tube (with conventional forks on the handlebar, with upside-down forks on the bike).

This is the total spring deflection G. Tighten the cable tie around the inner tube and push it against the outer tube.


This is how it works: Adjust the spring base yourself

Load the motorcycle with the rider, measure the distance from the cable tie to the fork base.

Third step:

Park the motorcycle, measure the distance from the cable tie to the end of the spring travel.

The difference between this value and the total spring travel G is the unloaded, static negative spring travel N1.


This is how it works: Adjust the spring base yourself

Same process as at the front, measured with fixed points on the rear frame and rear axle.

Fourth step:

Driver sits up. Measure the distance from the cable tie to the end of the spring travel again. The difference to G is the loaded, static negative spring deflection (N2). Determining the total travel of the rear wheel is a little more complicated.

The value from the manual can be used as an approximation; 120 to 130 mm are common for street motorcycles. To determine N1 and N2, mark a point on the rear of the motorcycle and measure from there to the wheel axle.

On the fork, the spring base is adjusted using threaded spindles at the upper end of the two bars, on the spring strut either conveniently using a hydraulic system with a rotary knob, or a little less comfortably using a hook wrench (see right).

Gradually approach the target values ​​mentioned at the beginning and check after every change on a known route whether the handling of your motorcycle has improved and whether you are still feeling well. If you have to increase the spring base for a correct N2 so that N1 becomes zero, the spring is too soft. Then the only way to help is to see a specialist who swaps the springs or the entire shock absorber – or you can come to terms with a compromise.


This is how it works: Adjust the spring base yourself

In the worst case, spring struts that are difficult to access must be removed in order to change the preload. Rule of thumb: 10 mm change at the rear corresponds to 3 to 5 mm at the shock absorber.

Heavy riders or riders who often ride with a pillion can set the N2 value about 5 mm lower, i.e. turn the spring base a little higher. Very light riders set 5 mm more negative suspension travel. Anyone who exhausts the tolerance range also influences the handling of their motorcycle: A higher spring base (i.e. less static negative spring travel) on the fork and shock absorber tends to make it more manageable, a deeper spring base makes it more stable.

Compression damping
The compression damping brakes the compression. The tighter it is set, the stronger the braking effect.

Spring base
The spring base, too “preload” called, determines the ratio of positive and negative spring deflection.

Spring stiffness
The property of a spring is given in Newton / mm, occasionally also in kg / cm: This is the amount of force required to compress the spring by the relevant amount.

High / low speed damping
Allows separate adjustment for fast and slow spring movements; has nothing to do with the speed being driven, but with the speed of the damper piston.

Negative travel
Available for rebound; changes depending on the driving situation.

Positive suspension travel
Is available for compression, changes depending on the driving situation.

Progression / Progressive
A chassis that opposes the compression movement with increasing resistance works progressively. Can be implemented using appropriate springs, a deflection or path-dependent damping.

Rebound damping
Brakes the rebound. If it is too strong, the motorcycle will remain compressed for too long and can no longer dampen the next wave. If it is too weak, the motorcycle rebounds too quickly and becomes restless.

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