“Sag” refers to the amount of suspension travel that is compressed when the bike is on flat ground under rider weight and riding gear. Setting the correct amount of sag on your suspension plays a crucial role in the overall performance of your full suspension mountain bike. Setting sag should always be the first step in setting up your suspension.
You might be thinking, why is setting sag so important? Sag affects the geometry of the bicycle, and frame designers design frames with geometry and sag in mind – ideally you would want to experience the bike in the way it was intended and designed to be ridden. When you have too much sag, you do not have a high enough spring rate to support your rider weight. This can result in pedal strikes and the suspension going through it’s travel too easily, and “bottoming out” often, and with rear shocks, this can result in pedal strikes and less pedaling efficiency.
When you do not have enough sag, or the spring rate is set too high, you risk not utilizing all of your suspension travel, and again affecting the intended geometry and overall performance of the bicycle.
We recommend first checking with your bicycle manufacturer on the suggested amount of sag they intended for your bike. If that information is not available to you, we recommend 25-35% sag depending on your shock size and intended use.