Most riders spend more time choosing handlebar grips than they do setting up their fork. Same bike, dialled fork vs. neglected fork, completely different machine. The gap between the bike feeling sharp and the bike feeling lifeless isn't carbon. It's twenty minutes of work and a shock pump.
Here's what nobody at the bike shop will tell you: a properly set up Fox Rhythm will out-ride a Factory with the settings all over the place. Same trail, same rider, every time. Your fork is the most expensive component on your bike. And if it's not dialled in, you've paid for performance you're never going to feel. For the full picture — fork and rear shock together — read our complete MTB suspension setup guide.
Why fork setup matters more than most upgrades
Think about what your fork actually does on every ride. It controls front tyre grip. It dictates whether the bike tracks straight through rock gardens or pings off every stone. It decides how much feedback comes through the bars and into your hands.
Set up properly, the bike disappears underneath you. Set up wrong, you're gripping tighter, braking earlier, riding more cautiously — and you don't know why. You'd get a bigger performance gain from twenty minutes with a shock pump than from a set of carbon handlebars. Same goes for tyre pressure — another free setup change that most riders get wrong.
The good news: this is fixable. And it's fixable today.
Step-by-step air pressure setup
Air pressure is the foundation. Get this wrong and no amount of fiddling with dials will save you. Let me break this down so you can do it tonight, in the garage, with one tool.
What you need: A quality shock pump (not a track pump — they're too imprecise for suspension work), a zip tie or the o-ring already on your stanchion, and a tape measure.
Step 1: Find your starting point. Set PSI roughly equal to your riding weight in kilograms — kit, pack, bottles, the lot. An 80kg rider starts around 75-80 PSI. That's a starting point, not your final number. Our MTB Setup Calculator gets you closer faster by factoring in your specific fork model.
Step 2: Attach the pump properly. Thread it onto the Schrader valve on top of the fork (left leg on most). Attaching the pump bleeds a tiny amount of air — that's normal, the gauge accounts for it. Always read and adjust pressure with the pump attached.
Step 3: Cycle the fork. Push down firmly on the bars 10-15 times to equalise the positive and negative air chambers. RockShox forks self-equalise, Fox don't — but cycle either way. Re-check the pressure after. It often drops a few PSI.
Step 4: Fine-tune through sag. Air pressure and sag are the same conversation. Your target sag determines your final pressure. That's next.
Setting sag properly
Sag is how far your fork compresses under your static body weight, expressed as a percentage of total travel. 150mm fork, 40mm of compression when you sit on the bike — that's roughly 27% sag.
Why it matters: sag sets where in the stroke your fork sits at rest. Too little, the fork rides high and skips off obstacles. Too much, you eat into the mid-stroke and the front end goes vague the moment the trail gets rough.
How to measure it:
- Set your air pressure to the starting point above.
- Push the o-ring (or zip tie) down to the dust seal.
- Kit up — full pack, full bottles, the works.
- Lean the bike against a wall or have a mate hold it.
- Climb on carefully, normal riding position, hands on bars, looking ahead. Don't bounce.
- Dismount without compressing further.
- Measure the gap between the o-ring and the dust seal.
- Divide by total travel, multiply by 100. That's your sag.
Sag targets by riding style:
| Riding Style | Sag % | Why | |---|---|---| | XC / Marathon | 20-25% | Firmer platform for climbing efficiency, less dive under braking | | Trail / All-Mountain | 25-30% | Best balance of small-bump sensitivity and big-hit support | | Enduro / Aggressive | 28-33% | Maximum grip and sensitivity for rough descending | | DH / Bike Park | 30-35% | Plush feel for sustained rough terrain at speed |
Sag too high? Add 5 PSI and re-measure. Too low? Release 5 PSI. Repeat until you're in range. The MTB Setup Calculator shortcuts this if you'd rather not iterate.
Rebound damping explained
Rebound controls how fast the fork extends after compressing — the red dial at the bottom of the leg.
Here's where most riders go wrong. They run rebound too fast because the bike feels "lively" in the car park. On the trail, that liveliness becomes a pogo stick. The bike bucks you off every bump. Traction goes. Confidence follows. Fixable.
The drop test:
- Stand next to the bike, both hands on the bars, compress the fork firmly.
- Release quickly. Watch the fork extend.
- Rebound too fast: the fork overshoots, the wheel may even lift off the ground.
- Rebound too slow: the fork creeps back, never fully extending before the next hit.
How to set it:
Start fully clockwise (slowest). Open one click at a time, do the drop test after each. You want the fork to return to full extension smoothly and with purpose — fast enough to be ready for the next bump, slow enough not to launch you.
Most riders land somewhere between 40-60% open. Heavier riders running higher pressure need more damping (slower). Lighter riders need less.
On the trail, correct rebound feels composed and planted. Bike bucks you on a stuttery section of roots? Rebound's too fast. Fork feels like it's sinking deeper through a long rough section — what mechanics call packing down? Rebound's too slow.
Compression damping: low-speed vs high-speed
If air pressure is the spring, compression damping is the shock absorber working against it.
Most trail and enduro forks have two compression circuits:
Low-speed compression (LSC): Slow shaft speeds — brake dive, pumping berms, pedal bob, weight shifts. More LSC means more support and less dive. Blue dial on Fox. Charger damper compression on RockShox.
High-speed compression (HSC): Fast shaft speeds — square-edge hits, drops, rock strikes. Too much HSC, the fork feels harsh and deflects on big hits. Too little, the fork blows through its travel.
Setting compression:
Start both at fully open (minimum). Ride a trail you know:
- Fork dives under braking or feels unsupported through corners? Add LSC a few clicks.
- Fork uses full travel too easily on moderate hits? Add HSC.
- Fork feels harsh on sharp impacts? Reduce HSC.
The principle: use as little compression as you can get away with. Too much compression damping kills small-bump sensitivity, which is the entire point of having suspension in the first place.
Volume spacers and tokens
Volume spacers (Fox) and Bottomless Tokens (RockShox) reduce the air volume in the positive chamber. The result: the fork gets progressively harder to compress the deeper it goes into its travel.
Add tokens when:
- You're using full travel on moderate hits, not just the biggest features.
- Bottom-out feels harsh despite correct air pressure and sag.
- You want lower pressure for sensitivity but need more end-stroke support.
Remove tokens when:
- There's a dead zone in the last third of travel — you can't access full travel even on the biggest hits.
- The fork ramps up too harshly mid-stroke.
Most forks ship with one token from the factory. Heavier or aggressive riders often add one or two. Simple job: unthread the top cap with a socket, drop tokens in, reassemble.
Common fork setup mistakes
Running too much air pressure. Number one error, by a distance. Riders inflate the fork until it feels firm and "supportive" — but firm isn't doing the job. If you're not using at least 70-80% of travel on a proper ride, there's too much air in it.
Ignoring negative air equalisation. Cycle the fork 10-15 times after any pressure change. Skip this and your sag measurement is wrong from the start.
Setting rebound too fast. Lively in the car park, lethal on the trail. Slower rebound than you think is almost always the right call.
Never touching stock settings. Manufacturers set compression and rebound to values that work okay for everyone and perfectly for nobody. You are not the 75kg test rider. Personalise.
Copying a mate's numbers. His weight, his riding style, his terrain, his tyres. None of it transfers. Setup is yours alone.
Order of operations
Don't try to set everything at once. There's a sequence:
- Air pressure — Set to roughly your weight in kg, then adjust for sag.
- Sag — Hit your target percentage for your riding style (table above).
- Rebound — Start slow, open until smooth without bouncing.
- LSC — Start open, add until braking and cornering support feels right.
- HSC — Start open, add only if you're blowing through travel on moderate hits.
- Volume spacers — Add if bottom-out is harsh despite correct sag; remove if you can't reach full travel.
Do this once properly, write your numbers in your phone notes, and you've got a baseline you can always return to. After that, small tweaks ride-to-ride are all you need. The MTB Setup Calculator generates a personalised starting point for your fork and shock if you'd rather skip the iteration.
Your fork is the most expensive component on your bike. Make it earn its keep. Then dial in your dropper post — the two work together to transform how the bike handles on descents. And if you're wondering whether upgrading other components is worth the money, the answer is almost always the same: dial in what you have first.
For the fitness behind the riding, NDY coaching at Roadman writes a plan around your week. Got a specific question about tokens, damper feel, or rebuild intervals? Ask Roadman — the answer's drawn from the wider archive.
