Your fork does more work than any other component on your mountain bike. It absorbs rocks, roots, drops, and braking forces — all while trying to keep your front tyre planted on the ground. And yet most riders spend more time choosing handlebar grips than they do setting up their fork properly.
Here's the thing: a correctly set up mid-range fork will outperform a badly set up top-tier fork every single time. If you want the full picture — fork and rear shock together — read our complete MTB suspension setup guide. A Fox Rhythm dialled in to your weight and riding style will feel better than a Factory with the settings all over the place. Setup is the upgrade that costs nothing but twenty minutes of your time.
Why Fork Setup Matters More Than Most Upgrades
Think about what your fork actually does on every ride. It determines how much grip your front tyre has in corners. It controls how much feedback you feel through the bars. It dictates whether the bike tracks straight through rock gardens or deflects off every stone.
When your fork is set up properly, the bike feels like an extension of your body. You stop fighting the trail and start flowing with it. When it's wrong, everything feels harder than it should — you're gripping tighter, braking earlier, and riding more cautiously than you need to.
Most riders would get a bigger performance gain from spending twenty minutes with a shock pump than they would from a new set of carbon handlebars. That's not an exaggeration. The same applies to tyre pressure — another free setup change that most riders get wrong.
Step-by-Step Air Pressure Setup
Air pressure is the foundation of everything. Get this wrong and no amount of fiddling with dials will save you.
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 that came on your fork stanchion, and a tape measure.
Step 1: Find your starting point. A decent rule of thumb is to start with PSI roughly equal to your riding weight in kilograms. So if you weigh 80kg in your kit and pack, start at around 75-80 PSI. This is just a starting point — not your final number. Use our MTB Setup Calculator for a more precise recommendation based on your fork model and weight.
Step 2: Attach the pump properly. Thread the shock pump onto the Schrader valve on top of the fork (left leg on most forks). Note that attaching the pump adds a small amount of air — this is normal and accounted for in the pump's gauge. Always read the pressure with the pump attached, and always add or remove air with the pump attached.
Step 3: Cycle the fork. After setting your initial pressure, push down on the bars firmly 10-15 times to equalise the positive and negative air chambers. Some forks (particularly RockShox models) have self-equalising negative air springs, but it's good practice regardless. Re-check the pressure after cycling — it may have dropped slightly.
Step 4: Fine-tune through sag. Air pressure and sag are two sides of the same coin. Your target sag percentage determines your final air pressure. More on that below.
Setting Sag Properly
Sag is the amount your fork compresses under your static body weight. It's expressed as a percentage of total travel. If your fork has 150mm of travel and it sinks 40mm when you sit on the bike, that's roughly 27% sag.
Sag matters because it determines where in the stroke your fork sits at rest. Too little sag and the fork rides high in its travel — it'll feel harsh and skip off obstacles instead of absorbing them. Too much sag and you're eating into your mid-stroke, leaving less travel for the big hits and making the front end feel vague and wallowy.
How to measure it:
- Set your air pressure to the starting point from above.
- Push the o-ring (or zip tie) down the stanchion until it sits against the dust seal.
- Kit up in your riding gear, put on your pack if you ride with one, and fill your bottles.
- Have a mate hold the bike upright, or lean against a wall.
- Mount the bike carefully and assume your normal riding position — hands on the bars, feet on the pedals, looking forward. Don't bounce.
- Dismount carefully without compressing the fork further.
- Measure the gap between the o-ring and the dust seal. That's your sag.
- Divide by total travel and multiply by 100 for your percentage.
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 |
If your sag is too high, add 5 PSI and re-measure. Too low, release 5 PSI. Repeat until you're in range. The MTB Setup Calculator can shortcut this process by giving you a pressure recommendation based on your specific fork model.
Rebound Damping Explained
Rebound controls how fast the fork extends back to full travel after being compressed. It's the red dial at the bottom of your fork (on Fox) or the red dial/knob on RockShox models.
This is where a lot of riders go wrong. Too-fast rebound is one of the most common setup mistakes in mountain biking, and it makes the bike feel unpredictable and bouncy — like riding a pogo stick.
The drop test method:
- Stand next to your bike and compress the fork firmly with both hands on the bars.
- Release quickly and watch how the fork extends.
- With rebound too fast, the fork will spring back and overshoot — the front wheel might even leave the ground slightly.
- With rebound too slow, the fork will creep back sluggishly and may not fully extend before the next compression.
How to set it:
Start with the rebound dial fully clockwise (slowest). Then open it (anti-clockwise) one click at a time, doing the drop test after each click. You're looking for the fork to return to full extension smoothly and quickly, but without overshooting or bouncing. It should extend with purpose but settle cleanly.
As a rough guide, most riders end up somewhere around 40-60% of the way from fully closed to fully open. Heavier riders and those running higher air pressures generally need more rebound damping (slower). Lighter riders need less.
On the trail, correct rebound feels composed and planted. If the bike bucks you on successive bumps (like a stuttery section of roots), your rebound is probably too fast. If the fork feels like it's sinking deeper and deeper through a rough section — packing down — your rebound is too slow.
Compression Damping: Low-Speed vs High-Speed
Compression damping controls how easily the fork compresses. If air pressure is the spring, compression damping is the shock absorber working against it.
Most trail and enduro forks offer two types of compression adjustment:
Low-speed compression (LSC): This affects fork movement during slow shaft speeds — think brake dive, pumping through berms, pedalling-induced bob, and body weight shifts. Increasing LSC gives you a more supportive platform and reduces dive. The blue dial on Fox forks controls LSC. On RockShox, it's the Charger damper's compression dial.
High-speed compression (HSC): This kicks in during fast shaft speeds — square-edge hits, drops, rock strikes. HSC controls how the fork reacts to sharp impacts. Too much HSC and the fork feels harsh on big hits, deflecting rather than absorbing. Too little and the fork blows through its travel too easily.
Setting compression:
Start with both LSC and HSC at their open (minimum) settings. Ride a familiar trail and pay attention:
- If the fork dives too much under braking or feels unsupported in corners, add LSC a few clicks at a time.
- If the fork uses full travel too easily on moderate hits, add HSC a few clicks.
- If the fork feels harsh on sharp impacts, reduce HSC.
The goal is to use as little compression damping as you can get away with while maintaining the support you need. Excessive compression damping makes the fork feel dead and reduces small bump sensitivity — which is the entire point of having suspension in the first place.
Volume Spacers and Tokens
Volume spacers (Fox calls them volume spacers, RockShox calls them Bottomless Tokens) reduce the air volume inside the positive air chamber. This makes the fork more progressive — meaning it gets harder to compress the deeper it goes into its travel.
When to add tokens:
- You're using full travel on moderate hits (not just the biggest features on the trail).
- You feel a harsh bottom-out despite having appropriate air pressure and sag.
- You want to run lower air pressure for better sensitivity but need more end-stroke support.
When to remove tokens:
- The fork feels like it has a dead zone in the last third of travel — you can never access full travel even on big hits.
- The fork feels overly progressive or ramps up too harshly mid-stroke.
Most forks come with one token installed from the factory. Adding one or two is common for aggressive riders or heavier riders who want to run softer spring rates without bottoming out constantly. It's a simple job — unthread the top cap with a socket, drop tokens in, and reassemble.
Common Fork Setup Mistakes
Running too much air pressure. The single most common error. Riders inflate their fork until it feels firm and "supportive" — but that just means it's not doing its job. If your fork isn't using at least 70-80% of its travel on a proper ride, you almost certainly have too much air in it.
Ignoring negative air equalisation. After any pressure change, cycle the fork 10-15 times. The negative air chamber needs to equalise with the positive chamber, and skipping this step means your sag measurement will be wrong.
Setting rebound too fast. If your fork bounces back quickly, it feels "lively" — but on the trail, it's launching you off every bump and reducing traction. Slower rebound than you think is almost always the right call.
Never adjusting from stock settings. Fork manufacturers set compression and rebound to middle-of-the-road values that work okay for everyone and perfectly for nobody. You are not a 75kg test rider on a specific test trail. Take the time to personalise.
Copying a mate's settings. Your ideal setup depends on your weight, riding style, terrain, tyre choice, and personal preference. Someone else's numbers are meaningless for your bike.
Quick Reference: Putting It All Together
Here's the order of operations for a complete fork setup:
- Air pressure — Set to roughly your weight in kg, then adjust for sag.
- Sag — Measure and hit your target percentage for your riding style (see 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 too easily on moderate impacts.
- Volume spacers — Add if bottom-out is harsh despite correct sag; remove if you can't access full travel.
Do this once properly, write your settings down somewhere, and you'll have a baseline you can always return to. From there, small tweaks ride-to-ride are all you need.
Use our MTB Setup Calculator to generate personalised starting points for your fork and shock — it'll save you a few rounds of trial and error and get you in the right ballpark straight away.
Your fork is probably the most expensive and most capable component on your bike. Make it earn its keep. And once your fork is sorted, make sure your dropper post is set up properly too — the two work together to transform how the bike handles on descents. If you are wondering whether upgrading other components is worth the money, the answer is usually: dial in what you have first.
