MTB Suspension Setup: Sag, Rebound and Where to Start

A brand-new fork or shock straight out of the box is set up for an average rider — which means it's set up for nobody in particular. Sag is the first and most important adjustment, and it takes five minutes.

Sag is how much your suspension compresses under your own body weight, at rest, in full riding gear. For most trail forks, aim for roughly 15–20% of total travel; for rear shocks on a trail bike, 25–30% is a common starting range. Enduro and DH setups often run slightly more rear sag for stability at speed.

To measure it: install the shock's o-ring (or wrap a zip-tie around a fork stanchion) flush to the wiper seal, sit on the bike in your normal riding position with feet on the pedals — ideally leaning against a wall for balance — then step off gently and measure how far the o-ring travelled from the seal. Adjust air pressure (or coil spring rate) up or down and repeat.

Rebound controls how quickly the suspension returns after compressing — too fast and the bike feels bouncy and skittish on repeated hits; too slow and it 'packs down', running out of travel on successive bumps because it never fully extends between them. A reasonable starting point: from fully closed (slow), open the rebound dial 8–12 clicks, then fine-tune from a curb-height drop — the front end should return to full extension in about one bounce, not two or three, and not so fast it pops back with a clunk.

Compression damping (where adjustable) is the setting most riders touch last, and that's the right order. Get sag and rebound right first — they affect every ride — then use low-speed compression to firm up support for pedalling efficiency, and high-speed compression to control how the suspension responds to square-edge hits, only once you have a baseline you trust.

Write your numbers down. Fork PSI, shock PSI, rebound clicks from closed, compression clicks from closed — a note in your phone saves you from re-guessing after every wash or travel trip.