Setting up your suspension before the season starts

On the first ride of the year the bike always feels slightly odd. It dives too much under braking, it skips over tar joints, it goes stiff in long corners. Nine times out of ten it is neither cold tyres nor a lack of practice on your part: it is suspension that has never been set up for you, or that has drifted over winter because the bike spent five months on its wheels, springs compressed, oil settled at the bottom of the fork legs.

The good news is that nearly everything that makes a bike unpleasant at the start of the season can be fixed for free, with a spanner, a tape measure and two hours. New parts come later — and often they turn out not to be needed. Here is the method in order, because the order matters more than the numbers.

Sag, before anything else

Sag is how far the suspension settles under the weight of the bike, and then under yours. It is the founding adjustment: it puts the bike in its working range. If the sag is wrong, every other setting is only compensating for that error, and you go round in circles for weeks.

There are two things to measure:

• Static sag: the bike alone on its wheels, nobody on board. It tells you how the spring rate relates to the mass of the machine.
• Rider sag: you on board, in full kit, feet on the pegs, in the riding position. That is the one that governs how the bike behaves.

Ballpark figures by segment, to be confirmed against the manufacturer's data for your machine: around 30 to 33 % of travel for road use, more like 25 to 30 % for sports use where you are chasing support, and 30 to 35 % for an adventure or off-road machine that has to keep ground clearance in compression. Static sag sits roughly around a third of rider sag. If it is nearly zero while rider sag is correct, your spring is too hard for the bike: you are compensating with preload and losing comfort. If it is very large, the spring is tired or too soft for your build.

Measuring properly: three readings, not two

A botched measurement is the number one source of error. You need three readings, and a second pair of hands.

1. Wheel off the ground, bike on a paddock stand, suspension fully extended: measure L1 (wheel spindle to a fixed point on the frame at the rear; dust seal to the underside of the yoke at the front).
2. Bike alone on its wheels, someone holding it upright: measure L2. Static sag = L1 minus L2.
3. You on board in full kit, in position, feet on the pegs: measure L3. Rider sag = L1 minus L3.

Two precautions that change everything: average two values, one coming down from the top and one coming up from the bottom, because seal friction throws the reading out by several millimetres. And always measure at the same point, marked with a pen. The full method is in our article on setting motorcycle sag.

Preload: it positions the bike, it does not stiffen it

This is the most widespread misunderstanding in the workshop. Preload does not change the spring rate. A 9 N/mm spring stays at 9 N/mm whether you wind it in or not. What preload changes is the resting position of the bike within its travel, so the attitude, so the weight distribution and the steering geometry.

In practice: you aim for the sag figure using preload. If you cannot get there — preload wound fully in and sag still too large, or preload fully backed off and sag too small — then the spring is the wrong one, and only then do you need to buy something. It happens quickly: most bikes come with springs calibrated for a rider of around 70 to 80 kg naked, which turns very optimistic with 15 kg of kit, a top box and a pillion. The subject is developed in our article on fork preload.

Rebound: the setting that makes a bike safe

Rebound damping controls how fast the suspension comes back after being compressed. Too fast and the bike bounces and goes light — that is what loses you the front on the way out of a corner on broken surfacing. Too slow and the suspension packs down: it has not finished returning when the next bump arrives, and the travel available shrinks with every impact.

The test is done stationary and costs thirty seconds: push down firmly on the seat or the bars, then let go sharply. The suspension should come back in one clean movement, without bouncing a second time and without crawling back up. To adjust, always start from the stop, wound gently in, then back off the number of clicks you count. Note the original setting before you touch anything: that is what lets you go back.

Compression: last, and sparingly

Compression damping slows the suspension going down. It manages braking, loading up and big hits. You touch it once sag and rebound are settled, because wound-in compression compensates very well — and very badly — for wrong sag: the bike feels stable and turns harsh, then lets go without warning on a bump mid-corner.

On forks with separate adjusters, low-speed compression handles weight transfer under braking while high-speed handles potholes. If you only have one adjuster, it does a bit of both.

The rule for test rides

One change at a time. Two clicks maximum between two runs. Same route, same pace, same cold tyre pressures. Change three things at once and you will never know which one did the work, and you will end up resetting everything. Write it all down in a notebook, or photograph a sticky note on the tank: setting, feel, date.

When it stops being a setup problem

There comes a point where the screwdriver cannot do anything more. The signs:

• Weeping at the fork seal, a ring of damp on the stanchion that comes back after you wipe it: the seal is finished and it is putting oil onto the front caliper. It is a replaceable part, and the procedure is described here. Worth dealing with promptly: leaking forks are also the kind of thing that gets picked up at the annual MOT, which a motorcycle takes once it is three years old.
• Black, thin oil at the change, with glitter in it: the oil has sheared, and the damping adjusters no longer produce any repeatable effect. Many manufacturers place the fork oil change somewhere in a range of a few tens of thousands of kilometres, or two to three years — the exact figure is in the workshop manual.
• Sag that no longer settles from one measurement to the next, or springs whose free length has dropped compared with new.
• Pitted or scored stanchions: damaged chrome will destroy any new seal within a few hundred kilometres.
• A shock that heats up and goes soft after twenty minutes: the nitrogen has gone, or the oil has fully emulsified.

On a bike past 60,000 km that has never seen a suspension service, having the existing kit rebuilt pays better than buying new: bushes, seals, fresh oil and springs matched to your weight usually give more than a top-end shock bolted onto tired forks.

The order to follow this weekend

Cold tyre pressures, a visual check of the stanchions and the linkage, greasing the pivots if that is scheduled. Then measure static and rider sag, front and rear. Then preload, to hit the target. Then rebound, using the bounce test. Then a ride. Then compression, two clicks, another ride. And you stop there for the day.

Target figures, the actual travel of your forks, the torque settings for the yokes and the wheel spindle all depend on model and year. The L'Atelier technical assistant gives you the manufacturer's values from the make, the model and the year, rather than the average of a forum thread that was talking about a different generation.