Preload (spring preload)

Preload is the amount a fork or shock spring is compressed when the suspension is fully extended. Adding preload does not make the spring stiffer; it changes where the suspension sits in its travel, so the bike sags less under the rider and rides higher.

Preload is set by measuring sag: the drop from fully extended to the bike's position with the rider on board in riding gear. Typical targets are given by the manufacturer or suspension tuner; off-road bikes use much larger sag figures than road bikes.

Adjust preload when riding with a passenger or luggage, using the collar on the shock (often with a C-spanner), a hydraulic knob, or caps on top of the fork. If correct sag needs extreme settings, the spring rate is wrong for your weight and a different spring is the real fix.