Bike Suspension Setup Guide for Beginners

Most mountain bikes come with suspension that's not set up for the rider. A few minutes of basic setup transforms how the bike feels. Here's a beginner-friendly guide to getting your suspension dialled in.

Why suspension setup matters

Suspension that's too soft bottoms out on every bump. Suspension that's too stiff feels like a rigid bike and beats you up on rough terrain. Properly set up, your suspension absorbs impacts, maintains tyre contact, and gives you more control and confidence.

The three key settings

1. Sag (the most important)

Sag is how much the suspension compresses under your body weight when you sit on the bike in riding position. It's expressed as a percentage of total travel.

• Trail/all-mountain: 25–30% sag
• Cross-country: 20–25% sag
• Downhill/enduro: 30–35% sag

How to set sag on an air fork

1. Find out your fork's total travel (e.g., 140mm). Check the manufacturer's sticker or manual
2. Push the rubber O-ring on the fork stanchion down to the seal
3. Sit on the bike in normal riding position (both feet on pedals, hands on bars). Have a friend hold you steady or lean against a wall
4. Carefully dismount without bouncing the fork
5. Measure how far the O-ring has moved from the seal. This is your sag
6. For 25% sag on a 140mm fork, the O-ring should be at 35mm
7. Too much sag? Add air pressure with a shock pump (5–10 psi at a time)
8. Too little sag? Release air pressure (small amounts at a time)

Important: You need a shock pump, not a regular tyre pump. Shock pumps are high-pressure, low-volume pumps designed for suspension. They cost £15–£30 and are essential if you own a bike with air suspension.

Coil forks and shocks

Coil suspension uses a metal spring instead of air. Sag is adjusted by changing the spring (different weight ratings) or adjusting the preload knob. If your coil fork is too soft or too firm, you may need a different weight spring.

2. Rebound

Rebound controls how fast the suspension extends back after being compressed. It's usually adjusted with a red dial at the bottom of the fork leg or on the shock body.

• Too fast (not enough rebound damping): The bike bounces and feels uncontrolled. The tyre can bounce off the ground after hits
• Too slow (too much rebound damping): The suspension doesn't recover between successive bumps. It “packs down” and sits lower and lower in the travel
• Starting point: Set rebound to the middle of its range, then test ride. If the bike bounces after drops or bumps, slow the rebound down. If it feels dead and packed down on rough sections, speed it up

3. Compression

Compression damping controls how easily the suspension compresses. Not all forks have external compression adjustment.

• Open: Full suspension travel, most compliant. Best for descending and rough terrain
• Pedal/Trail: A middle setting that reduces bobbing when pedalling but still allows the suspension to absorb bumps
• Locked: Suspension is very stiff or fully locked. Only for smooth road riding or hard climbs. Never ride locked over rough terrain — it puts huge stress on the lockout mechanism

Quick setup process

1. Set sag to 25–30% using a shock pump
2. Set rebound to the middle of its range
3. Set compression to open (if adjustable)
4. Go for a test ride on your usual trails
5. Adjust rebound based on how the bike feels (bouncy = slow it down, dead = speed it up)
6. Fine-tune air pressure if needed (bottoming out = add 5 psi, harsh = remove 5 psi)

When to get a professional suspension service

Suspension forks and shocks need periodic servicing (oil changes, seal replacement) every 50–100 hours of riding or annually. Signs your suspension needs servicing:

• Oil leaking from the fork seals
• Suspension feels sticky or harsh
• Strange noises (gurgling, clunking)
• Loss of damping (fork dives too easily or rebounds too fast regardless of settings)

Basic lower leg services (seal and oil change) can be done by most bike mechanics. Full damper rebuilds may need a specialist suspension service centre.