Suspension Systems

What are Suspension Systems in Mountain Biking?

Suspension systems are central components of modern mountain bikes that absorb shocks and vibrations from the terrain. They increase comfort, improve traction and enable higher speeds on technically challenging trails. The choice of the right suspension system depends significantly on the discipline, riding style and preferred trail conditions.

Basic Suspension Types

Hardtail - Fork without Rear Suspension

Hardtail mountain bikes feature only a suspension fork on the front wheel. The rear end is rigid and has no suspension. This design offers several advantages:

• Lower weight by dispensing with rear damper and additional bearing systems
• More efficient power transfer when pedaling, especially uphill
• Lower maintenance due to fewer moving parts
• Lower purchase costs compared to fully suspended bikes

Hardtails are particularly suitable for:

• Cross-Country Racing
• Marathon races
• Training sessions at high pace
• Less technical trails with moderate obstacles

Full Suspension - Fully Suspended System

Fully suspended mountain bikes have both a suspension fork on the front wheel and a damper for the rear end. This design offers:

• Maximum traction through constant ground contact of both wheels
• Higher comfort on technically challenging trails
• Better control at high speeds
• Reduced fatigue of the rider through absorption of shocks

Full suspension bikes are optimal for:

• Downhill Racing
• Enduro competitions
• Extremely technical trail descents
• Bike parks with jumps and drops

Fork Technology

Travel by Discipline

Air Spring vs. Coil Spring

Air Spring:

• Lighter than coil spring
• Spring rate adjustable via air pressure
• Lower maintenance
• Temperature sensitive
• Ideal for Cross-Country and Trail

Coil Spring:

• More consistent performance over the entire travel
• Not temperature sensitive
• Heavier than air spring
• Spring rate only changeable by swapping the spring
• Preferred for Downhill and Freeride

Damper Technology

Rebound Damping

Rebound damping controls the speed at which the suspension extends after compression. Correct adjustment is crucial:

• Too fast: Bike bounces up after obstacles, loses ground contact
• Too slow: Suspension packs down on multiple obstacles, doesn't use travel optimally

Compression Damping

Compression damping regulates resistance during compression. Modern dampers distinguish between:

Low-Speed Compression:

• Resistance during slow movements (weight shifts, pedaling)
• Prevents unnecessary bobbing

High-Speed Compression:

• Resistance during fast impacts (roots, rocks, drops)
• Protects against bottoming out

Platform Damping

Many modern dampers offer a platform function:

• Increases resistance to compression
• Reduces energy loss when pedaling
• Typically three modes: Open, Platform, Lock

Kinematics Systems for Rear Suspension

Single Pivot

• Simplest design with one main pivot point
• Low maintenance and robust
• Moderate anti-squat behavior
• Example: Trek Session, Specialized Demo

Four Bar Linkage

• More complex kinematics with multiple pivot points
• Optimizable curve over travel
• Better separation of drive and suspension movement
• Example: Specialized Stumpjumper, Giant Trance

Horst Link

• Pivot point on chainstay, directly in front of rear axle
• Decouples rear suspension from chain tension
• Constant chain line over travel
• Patent originally from Specialized

VPP (Virtual Pivot Point)

• Two counter-rotating links
• Migrating virtual pivot point
• Excellent anti-squat properties
• Very sensitive response
• Developed by Santa Cruz/Intense

Setup and Adjustment

SAG Adjustment

SAG (static sag under rider weight) is the most important basic setting:

Cross-Country:

• 15-20% of travel
• Higher efficiency when pedaling

Trail / All-Mountain:

• 20-25% of travel
• Balance between efficiency and comfort

Enduro / Downhill:

• 25-30% of travel
• Maximum traction and reserves for big hits

Checklist: Perfect Suspension Setup

• Check SAG adjustment (with rider weight + equipment)
• Adjust front rebound (3-4 clicks from fully fast)
• Adjust rear rebound (similar to fork)
• Adjust Low-Speed Compression (on long climbs)
• Test High-Speed Compression (on technical descents)
• Check air pressure every 4-6 weeks (air loss)
• Oil service according to manufacturer specifications (usually 50-100 operating hours)
• Check seals for wear

Maintenance and Care

Regular Maintenance Intervals

After every ride:

• Remove coarse dirt with water
• Clean stanchions/legs and treat with silicone spray
• Visual inspection for oil leaks

Every 25 operating hours:

• Small inspection: check seals
• Thoroughly clean stanchions
• Check and adjust air pressure

Every 50-75 operating hours:

• Service of lower bushings
• Change oil in suspension fork
• External damper service

Every 100-150 operating hours:

• Complete service of all seals
• Oil and grease change
• Inspection of internal components

Performance Optimization

Tuning to Riding Style

Aggressive riders:

• Higher air pressure (less SAG)
• More Low-Speed Compression
• Faster rebound

Technical riders:

• Standard SAG (25%)
• Open Low-Speed Compression
• Moderate rebound

Comfort-oriented riders:

• More SAG (30%)
• Open compression
• Slower rebound

Trail Adaptations

Modern Suspension Innovations

Electronic Damper Systems

• Fox Live Valve: Automatic adjustment via sensors
• RockShox Flight Attendant: AI-supported damper adjustment
• Advantages: Optimal performance without manual adjustment
• Disadvantages: Higher weight, dependence on electronics, higher price

Semi-Active Systems

Combination of mechanical and electronic damping:

• Faster response than purely electronic systems
• Lower energy requirement
• Fallback to mechanical mode in case of electronics failure

Common Problems and Solutions

Problem: Suspension bottoms out

• Solution: Increase air pressure or stiffer spring
• Alternative: Add volume spacer

Problem: Suspension bobs when pedaling

• Solution: Increase Low-Speed Compression
• Alternative: Activate platform mode

Problem: Suspension feels hard

• Solution: Check SAG adjustment, possibly reduce air pressure
• Maintenance: Service might be due (old seals, dirty oil)

Problem: Loud noises during compression

• Solution: Clean and lubricate bushings
• Check: Inspect bearings for play

Related Topics

• Mountain Bikes - Overview
• Tire Profile and Air Pressure
• Cross-Country Racing
• Downhill Racing
• Enduro Racing