How We Tune a Suspension Fork.
A suspension fork set up correctly feels like witchcraft. Set up incorrectly, it’s just dead weight. Here’s the process we use to dial in every trail and mountain bike before it leaves the workshop.
Published
2025-01-09
Read time
7 min read
Sag: The Starting Point
Sag is the amount the fork compresses under the rider’s static weight. The correct sag is typically 15 to 20 percent of total travel for a cross-country fork, and 25 to 30 percent for trail and enduro applications. A trail fork with 140mm travel should sit 35 to 42mm lower when the rider is seated in the attack position.
Setting sag requires adjusting air pressure in the positive chamber. More air equals less sag. The correct pressure is not a number from a chart — it is the pressure at which the fork sits at the correct sag for that specific rider, on that specific bike, with that specific gear loaded.
Rebound: The Most Misunderstood Setting
Rebound controls how fast the fork extends after compression. Set it too fast, and the fork kicks back into the wheel on successive hits, destabilising the bike. Set it too slow, and the fork packs down over repeated impacts and loses travel.
The correct rebound is found by compressing the fork quickly and watching it return. It should extend fast enough to track the trail but slow enough that there is no kickback. On rough terrain, a fast-rebounding fork will feel nervous. A slow-rebounding fork will feel dead. The correct setting is the one that disappears — where you stop thinking about the fork and start thinking about the trail.
Compression: Advanced Tuning
High-speed and low-speed compression damping control how the fork responds to different input velocities. Low-speed compression affects pedalling efficiency and gradual weight shifts. High-speed compression affects how the fork handles sharp impacts like square-edged rocks and roots.
Most riders benefit from leaving high-speed compression close to factory settings and tuning low-speed compression to their preference — firmer for more efficient pedalling platforms, softer for more active trail feel. The interaction between these settings and rider weight means that fork tuning is always iterative. We recommend a minimum of two full rides between adjustments.