rockshox calculator

How this RockShox calculator works

This tool gives you a practical baseline for fork pressure, shock pressure, and sag targets using common setup ranges for RockShox air suspension. It is designed for riders who want a fast way to get close before doing the final dial-in on real terrain.

Suspension setup always includes compromise: small-bump comfort, mid-stroke support, and bottom-out resistance all pull in different directions. The goal of this calculator is not to replace manufacturer charts, but to provide a consistent, rideable starting point when you are between sizes, changing bike setup, or testing new trails.

What you get from the calculator

• Recommended fork pressure in psi and bar.
• Recommended rear shock pressure in psi and bar.
• Target sag in millimeters for both front and rear travel.
• Estimated shock-body sag in mm if you provide rear shock stroke.
• Optional pressure correction if you already measured sag and entered current pressure.

How to measure sag correctly

Fork sag steps

1. Set compression open (or fully open trail mode).
2. Slide the o-ring down to the dust wiper.
3. Get on the bike in full riding kit, neutral attack position.
4. Gently cycle suspension once and settle without bouncing.
5. Step off carefully and measure o-ring movement in mm.

Rear sag steps

1. Open rear compression or put the lever in open mode.
2. Reset shock o-ring.
3. Stand in normal riding position, not seated unless you tune for seated climbing only.
4. Measure rear wheel sag in mm (or shock sag if you know leverage ratio).

Recommended sag ranges by riding style

• XC / Marathon: 15–20% fork, 20–25% rear.
• Trail: 18–25% fork, 25–30% rear.
• Enduro: 20–28% fork, 28–33% rear.
• Downhill / Park: 25–30% fork, 30–35% rear.

If you frequently bottom out hard, add pressure in small steps (2–5 psi) and consider additional volume tokens. If the bike feels harsh and deflects on chatter, remove a little pressure or increase sag slightly.

Practical tuning sequence after your baseline

1) Set sag and pressure first

Never tune rebound or compression aggressively until air spring pressure and sag are in range.

2) Set rebound

Start near the middle of your click range. If the bike feels like a pogo stick, slow rebound (more damping). If it packs down through repeated hits, speed rebound up slightly.

3) Set compression

Add low-speed compression if the bike dives too much under braking or pumping. Back it off if grip suffers on roots and square-edge bumps.

4) Control bottom-out

If you are reaching full travel too easily on normal runs, first add 2–5 psi. If that makes mid-stroke too firm, return pressure and add a volume spacer instead.

Why your final number may differ from charts

• Different frames have different leverage curves.
• Riding stance and body position change effective loads dramatically.
• Trail speed, terrain, and tire pressure all influence suspension behavior.
• Temperature can shift air spring feel over long rides.

Frequently asked questions

Is this only for RockShox forks and shocks?

The assumptions are tuned around common RockShox behavior, but the same process can help with most modern air suspension systems.

Should I prioritize comfort or support?

Trail riders usually prefer a balanced setup around 20–25% front and 27–30% rear. Racers may go firmer for support and response.

How often should I re-check sag?

Re-check whenever you change tires, cockpit fit, riding kit weight, or trail focus. It is also smart to check at the start of each season.