Summary

A leverage curve describes how the mechanical advantage between a bicycle’s rear wheel and rear shock changes as the suspension moves through its travel. By shaping how much force is applied to the shock at different points in the stroke, the leverage curve strongly influences small-bump sensitivity, mid-stroke support, bottom-out resistance, and overall ride character.

Key Facts

Category: Concepts
Defined as: Ratio of rear wheel movement to shock movement
Expressed as: A curve plotted across suspension travel
Applies to: Full-suspension bicycles
Directly affects: Shock feel, spring behavior, bottom-out control
Interacts with: Suspension linkage, shock tune, spring rate
Common curve types: Progressive, linear, regressive
Evaluated during: Frame design and suspension tuning

Overview

The leverage curve is one of the most important — and least visible — elements of full-suspension bike design. While riders can see suspension travel numbers and shock sizes, the leverage curve explains how that travel is actually delivered. Two bikes with the same travel and shock can feel completely different because their leverage curves are shaped differently.

At its simplest, leverage is a mechanical ratio. It describes how much the rear wheel moves for a given amount of shock compression. Early in the travel, the suspension may have high leverage, meaning the wheel moves a lot for a small amount of shock movement. Deeper in the travel, leverage may decrease, requiring more force to compress the shock further.

This changing relationship is what gives suspension its character. A well-designed leverage curve allows a bike to feel supple over small bumps, supportive through the middle of the stroke, and resistant to harsh bottom-outs. Poor leverage curve design can result in a bike that feels wallowy, harsh, or unpredictable, regardless of shock quality.

Modern suspension design places enormous emphasis on leverage curves because they define how effectively a shock can do its job. Springs and dampers can only work within the mechanical framework the frame provides.

How It Works

Leverage Ratio Explained

Leverage ratio is typically expressed as a number, such as 2.8:1. This means the rear wheel moves 2.8 units for every 1 unit of shock movement.

As the suspension compresses, this ratio usually changes. The plot of leverage ratio versus suspension travel is known as the leverage curve.

Relationship Between Wheel and Shock

The suspension linkage determines how wheel movement is transferred to the shock. Link lengths, pivot locations, and shock mounting positions all influence this relationship.

Because linkages rotate through arcs rather than moving linearly, the leverage ratio is rarely constant. This is why the curve matters more than a single number.

Force Translation

A higher leverage ratio:

Amplifies wheel force at the shock
Makes the suspension feel more sensitive
Requires less force to move the shock

A lower leverage ratio:

Reduces force applied to the shock
Increases resistance to compression
Improves bottom-out control

The leverage curve defines how this force translation evolves throughout the stroke.

Common Types of Leverage Curves

Progressive Leverage Curves

A progressive leverage curve decreases leverage as the suspension compresses. Early in the travel, leverage is higher; deeper in the stroke, leverage is lower.

Characteristics:

Excellent small-bump sensitivity
Increasing support deeper in the travel
Improved bottom-out resistance

Progressive curves are common on modern trail, enduro, and downhill bikes because they work well with both air and coil shocks.

Linear Leverage Curves

A linear leverage curve maintains a relatively consistent leverage ratio throughout the travel.

Characteristics:

Predictable feel
Even shock loading
Requires careful spring selection

Linear curves pair well with coil shocks, which naturally provide a linear spring rate.

Regressive Leverage Curves

A regressive leverage curve increases leverage as the suspension compresses.

Characteristics:

Easy initial movement
Reduced support deeper in the stroke
Higher bottom-out risk

Regressive curves are rare in modern designs because they make suspension difficult to control at higher impacts.

Interaction With Spring Type

Air Springs

Air springs are inherently progressive, meaning resistance increases as they compress. Most modern frames are designed with leverage curves that complement this behavior.

Progressive leverage + air spring = controlled ramp-up
Linear leverage + air spring = strong end-stroke progression

Air shocks allow some tuning through volume spacers, but the leverage curve still sets the foundation.

Coil Springs

Coil springs are largely linear. This places more responsibility on the leverage curve to provide end-stroke support.

Progressive leverage curves are often preferred with coils
Linear leverage curves require careful spring rate selection

The rise of coil shocks on trail and enduro bikes has renewed focus on leverage curve shape.

Mid-Stroke Support and Ride Feel

What Is Mid-Stroke Support?

Mid-stroke support refers to how well the bike holds itself up during aggressive riding, pumping terrain, or cornering.

The leverage curve heavily influences this:

Too much leverage mid-stroke can feel wallowy
Too little can feel harsh or dead

Designers aim for a balance where the bike remains composed without sacrificing traction.

Rider Perception

Riders often describe leverage curve effects using terms like:

“Plush”
“Supportive”
“Blowy”
“Firm”

These sensations are not solely the result of shock tuning. They originate in the leverage curve.

Bottom-Out Control

End-Stroke Behavior

As the suspension approaches full compression, the leverage curve determines how hard it is to use the last portion of travel.

A well-shaped curve:

Allows full travel when needed
Prevents harsh bottom-outs
Protects frame and shock

Poor end-stroke behavior often leads riders to overcompensate with excessive compression damping or volume spacers.

Leverage Curve vs Shock Tune

Division of Responsibility

The leverage curve defines the mechanical framework. The shock tune fine-tunes behavior within that framework.

Leverage curve: big-picture behavior
Shock tune: refinement and control

Trying to “fix” a poor leverage curve with shock tuning has limits. No amount of damping can fully overcome unfavorable kinematics.

Consistency Across Conditions

A good leverage curve allows the shock to operate in an efficient range across different terrains and riding styles, reducing the need for constant adjustment.

Influence of Suspension Design

Linkage Layout

Different suspension layouts produce different leverage curve tendencies:

Short-link systems allow aggressive shaping
Single-pivot systems are more constrained
Multi-link systems offer greater tuning freedom

Designers often iterate leverage curves extensively during development, making small changes to pivot positions to achieve desired results.

E-MTB Considerations

E-MTBs add mass and sustained torque to the suspension system. Leverage curves on e-MTBs are often tuned to provide:

More mid-stroke support
Stronger end-stroke resistance
Stability under prolonged load

Common Misconceptions

“More Progression Is Always Better”

Excessive progression can make suspension difficult to use fully and lead to harshness. Balance matters more than extremes.

“Shock Size Determines Feel”

Shock size influences performance, but leverage curve shape often matters more than shock dimensions alone.

“Leverage Curves Are Only for Engineers”

While technical, leverage curves directly affect how a bike feels to ride. Understanding them helps riders make better setup and purchase decisions.

Practical Implications for Riders

Setup

Riders cannot change leverage curves, but understanding them helps with:

Spring rate selection
Volume spacer tuning
Compression and rebound adjustments

Bike Comparison

Two bikes with identical travel numbers can feel dramatically different because of leverage curve design. Travel alone does not define performance.

Longevity

Poorly managed leverage curves can place excessive stress on shocks, bushings, and frames. Good curves distribute load more evenly across the stroke.

Industry Context

As suspension design has matured, leverage curves have become a primary differentiator between platforms. Modern design tools allow engineers to simulate and refine curves before a prototype is ever built.

This shift has moved suspension development away from trial-and-error and toward deliberate, data-informed design.

Notable Implementations

Modern trail bikes: Progressive curves with strong mid-stroke support
Enduro bikes: Aggressive progression for impact control
Downhill bikes: Carefully tuned curves for high-speed stability
E-MTBs: Supportive curves for added mass and torque

Related Terms

References

Suspension kinematics engineering literature
Bicycle frame design white papers
Shock manufacturer tuning guides
Academic studies on linkage mechanics
Industry technical analyses and teardown features