Bike suspension setup: sag, rebound, compression | Competitive Cyclist

How do I set my bike suspension? | Competitive Cyclist

A concise, rider-first guide to sag, rebound, compression and service intervals so your fork and shock are safe, efficient, and confidence-inspiring on every ride.

TL;DR

Set sag by percentage: front ~15–25%, rear ~20–30% depending on discipline and travel.
Rebound: start middle of the range and slow it until the bike feels planted, then speed up a touch.
Compression: use low-speed compression for pedalling control and high-speed for big hits; tune in small steps.
Service: lower-leg / air-service ~50 hours, damper service ~100–200 hours; race or wet conditions shorten intervals.

The Short Answer

If you ride mountain bikes and want your suspension to be predictable and fast, get sag right first, then tune rebound for recovery speed, then dial compression for platform and impact control. Typical targets are roughly 15–25% fork sag and 20–30% rear shock sag; start rebound at the factory baseline and adjust 2 clicks at a time until you stop feeling a pogo or packing. Service lower legs and seals every ~50 hours and a full damper rebuild at ~100–200 hours, sooner if you ride hard or in mud. Correct setup saves watts climbing, improves grip in corners, and prevents damage that costs hundreds in repairs.

Related Categories

Parts and tools that help you set and maintain suspension.

Suspension mountain-bike forks — buy forks or compare travel/stanchion options for your riding style
Bike tools & maintenance — shock pumps, torque wrenches and service tools to get setup right
Bike tool kits — portable kits for air-pressure checks and roadside tweaks
Rear suspension parts & accessories — springs, tokens, and mounts to tune progressivity

What It Depends On

Discipline and travel: XC (short travel) wants less sag and more efficiency; enduro/DH (long travel) needs more sag for traction and bottom-out control.
Rider weight and kit weight: sag settings are a percentage of travel, so heavier riders need more spring force or volume reduction.
Tire pressure, geometry, and wheel size: suspension interacts with traction and handling; don’t tune suspension in isolation. See front fork choices under Suspension mountain-bike forks.
Terrain and conditions: wet, rooty rock needs more traction (softer), fast buffed tracks benefit from firmer compression for stability.
Service history: seals and oil degrade—old oil changes damping characteristics, so fresh service may change your tuning baseline.

Decision Framework

Step 1 — Sag first: set rider sag (wear normal kit, helmet off). Aim for the percentages in the table below.
Step 2 — Rebound second: start near manufacturer's baseline. If the bike kicks back between bumps (pogo), slow rebound 2–3 clicks. If it stays low after hits (packs), speed it 2–3 clicks.
Step 3 — Compression last: set low-speed compression to control pedaling bob without killing small-bump sensitivity. Add high-speed compression if you’re bottoming on big hits.
Step 4 — Validate on a consistent test lap: hard braking into a corner, a compressed root section, and a big landing. Tweak 1–3 clicks and repeat.
Step 5 — Record numbers: log sag %, rebound clicks, compression clicks and service dates in your phone so you can repeat a known good baseline.

Comparison Table

Profile

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XC / Light Trail

Trail / All-mountain

Enduro / DH

Fork sag (travel %)

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10–15%

15–25%

20–30%

Rear sag (travel %)

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15–20%

20–30%

25–30%

Rebound baseline

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Faster recovery; fewer clicks (8–12)

Neutral; mid-range clicks (10–14)

Slower recovery to stay planted (12–18 clicks)

Compression baseline

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Open-ish for sensitivity; light LSC

Balanced LSC + modest HSC

Firmer HSC to prevent bottoming

Service guidance (recommended)

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Lower-leg/air: 50 hrs; damper: 125–200 hrs

Lower-leg/air: 50 hrs; damper: 100–150 hrs

Lower-leg/air: 25–50 hrs; damper: 75–150 hrs (race use shorter)

Deep Dives

Sag: what it is and how to set it

Sag is the amount your suspension compresses under your weight, expressed as a percent of total travel. It sets the bike's neutral geometry and where the shock/fork operates in the travel curve.

How to measure:

Put on your normal ride kit and shoes, remove any pack, and sit on the bike in a neutral riding position (hands on grips, feet on pedals). Have a friend steady the bike, or lean against a wall.
Use an O-ring or zip-tie on the fork stanchion and shock shaft. Compress to settle and then come off the bike without riding. Measure sag in mm and convert to percent (sag mm ÷ travel mm × 100).
Adjust spring preload (coil) or air pressure (air spring) until you hit the target percent.

Why it matters: wrong sag shifts your geometry and ride behavior. Too little sag reduces traction; too much sag causes packing and poor cornering geometry.

Common mistakes: measuring while wearing a backpack, or changing tire pressure between measurements. Both invalidate sag numbers.

Rebound & Compression: what they do and how to tune

Rebound controls how quickly the fork/shock extends after a compression. Too fast = pogo and loss of traction. Too slow = packing and reduced mid-travel support.
Compression damping resists compression. Low-speed compression (LSC) affects pedaling and weight transfer; high-speed compression (HSC) affects impacts and square-edge hits.

Tuning method:

Start with rebound at factory baseline. Ride a loop with consecutive bumps. If the bike fires back too hard, slow rebound 2 clicks. If it fails to recover and feels sluggish, speed it 2 clicks.
For compression: close LSC until pedaling bob reduces, but stop before harshness appears. Add HSC for bottoming or harsh landings. Make incremental changes and test.

Trade-offs: increasing compression improves support and reduces bottoming but reduces small-bump compliance and grip. Rebound interacts with compression — fix rebound first.

Edge Cases / Exceptions

E‑bikes: higher system weight often needs firmer springs or volume spacers and shorter recommended sag percentages to protect against packing.
Tandems or big rider-shifts: use coil springs or higher-pressure air springs; sag targets remain useful but require different hardware.
Carbon frames with specific clearance/limits: always follow frame maker torque and travel limits; consult a shop for custom valving.
If your fork/shock feels harsh after fresh service: new oil and seals can change damping — retune rebound/compression after service.
If you suspect internal damage (oil loss, grinding, inconsistent damping), stop riding and consult a tech. Safety first.

Checklist

Wear your usual ride kit and set SAG, record % and pressures.
Use a quality shock pump and a digital gauge for repeatability.
Adjust rebound before compression; log click counts.
Test on a consistent loop and make small changes (1–3 clicks).
Keep a service log: date, hours ridden, and what was done.
If you lack tools or confidence, book a damper service at a certified shop.

Brand Picks (Optional)

Lightweight XC fork (100–120 mm travel) — for minimal weight and quick handling
All-mountain/trail fork (130–150 mm) — versatile balance of suppleness and control
Enduro fork (160–180 mm+) — high-volume internals for big-hit resistance

Related Categories

Need parts, tools, or cleaning gear after tuning? Start here.

Bike fork parts & accessories — seals, lowers and tokens to change fork progressivity
Bike cleaning kits & accessories — keep stanchions and seals contaminant-free
Rear suspension parts & accessories — hardware, spacers and shock parts for tuning

Key Takeaways

Sag sets geometry: front ~15–25%, rear ~20–30% depending on discipline.
Tune rebound before compression; small steps (1–3 clicks) matter.
Service lower legs ~50 hours; damper service 100–200 hours; shorten for race/mud.
Record settings and validate on a consistent test lap for repeatability.

FAQs

How often should I check sag?

Check sag whenever you change tire pressure, wheels, or significant kit weight. Otherwise, check once a month or before a big day of riding.

My suspension feels fine but makes a slight noise. Should I ride it?

Minor noises can be contamination or low oil. If the noise is accompanied by inconsistent damping or oil on the stanchions, stop riding and consult a tech. Small issues can become expensive failures.