Springs

Fork Springs Explained

The spring side of your fork determines how much force it takes to compress and how the resistance builds through the travel. Getting the spring right matters more than any damper adjustment — a fork with the wrong spring rate will never feel good regardless of how much you fiddle with compression and rebound knobs.

Air Springs

Most modern forks use air springs, where the spring rate is set by air pressure. The advantage is infinite adjustability with a shock pump and low weight. RockShox uses DebonAir and DebonAir+ assemblies, Fox uses FLOAT. Both are self-contained cartridges that can be swapped without specialist tools — just release the air, undo the top cap, and slide the old one out. If your fork has lost its initial plushness and re-greasing the air spring didn't fix it, the seals inside the air spring assembly are likely shot.

Volume Spacers and Tokens

Volume spacers (Fox) and tokens (RockShox) reduce the air volume in the positive chamber, making the fork ramp up faster through its travel. More spacers means more bottom-out resistance without changing the sag point. One or two spacers suit most trail riders. Three or more is typical for enduro and DH where you need the fork to resist harsh bottom-outs at speed. They cost a few quid each and make a noticeable difference.

Coil Conversions

Coil conversion kits replace the air spring with a steel coil, giving a more linear spring curve — consistent force throughout the travel rather than the progressive ramp of air. The trade-off is weight (150–200g heavier) and fixed spring rate (you need the right weight coil rather than just adjusting pressure). Vorsprung Smashpot and MRP Ramp Control Coil are the main kits for RockShox forks. The ride feel is noticeably different — more traction in the first third of travel, less harsh on repeated square-edge hits.

Choosing the Right Spring Rate

For air springs, start with the manufacturer's recommended pressure for your weight and adjust from there — you want 20–25% sag for trail riding, 25–30% for DH. For coil conversions, the spring rate depends on rider weight, fork travel and riding style. Manufacturers provide weight charts, but expect to try two springs before landing on the right one.