Suspension part 2

Setting the sag
 
As mentioned in part one, setting the static sag of the motorcycle is the starting point to getting your bike in the realm of using the suspension correctly. As you set the sag you will uncover some basic flaws in your settings that can be arrived at no other way.

The static sag is set with the bike under itís own weight, and is backed up by two further tests; the One G Test (with rider and normal weight load in place); and measuring the amount of suspension travel used while riding. To get the springing rates correct for your motorcycle, this process must be worked through in sequence. If you decide to miss one of the steps or allow the settings to fall outside the guidelines given, youíll be missing at least one or more ingredients to getting your suspension working the way itís designed to.

So, letís discuss exactly what the static sag is ó Static: motionless, inactive. Pertaining to bodies at rest or equilibrium. Sag: curve downwards under pressure. Give way. Hang loosely ó so we are in affect measuring the ďcurve downwards of a body at restĒ. The exact measurement for what to set the static sag at will differ from bike to bike, rider to rider, and will vary depending on how the bike is to be used. There are however some fairly stable guidelines on where to start.

First you need to know how much travel your suspension has by extending it fully and measuring in the direction of travel. On the forks this is easy as you simply measure from the top part of the lower fork leg, to the bottom of the triple clamp.

On the rear, you need to pick two points that are at each end of the travel. For example, the grab rail and the axle. Unload the suspension fully by taking the weight off it and measure as shown in pictures 1 and 2. This will give you the unloaded distance.

To get the fully extended length of the suspension itís important that you take any sag out by lifting whichever end of the bike you are measuring. If possible itís best to actually lift the wheel off the ground when doing so, to ensure you are getting accurate measurements. This can be done by having someone balance the bike of the side stand (if a centre stand isnít fitted) while you do the measuring.

Once you have this distance, stand the bike upright, and allow it to sit under itís own weight, measuring from the same points. Itís best if you give the bike a couple of bounces up and down, then allowing it to settle before measuring. This guarantees the suspension is settled to itís true sag. The difference between these two measurements is the static sag.

The rear sag should be somewhere between zero and 10 millimetres and the front between 20 and 30 millimetres. As mentioned earlier, there will be some differences from bike to bike and rider to rider, depending on how you are using your bike, but it should always fall within this range. For example, during racetrack use you will find that firmer is better (within reason), whereas on the open road that is not always the case.

Next, the One G Test...