Linkage is a suspension simulation and design tool used by bike engineers, frame builders, and enthusiasts to model how suspension systems behave under real-world conditions. If you’ve ever wondered why two bikes with the same travel feel completely different, Linkage is the kind of tool that explains it — by calculating leverage ratios, anti-squat, pedal kickback, and axle path across the full range of travel.
For geometry-minded riders, Linkage bridges the gap between static frame measurements (which we cover in our geometry explained guide) and the dynamic behavior of the suspension system. Understanding both sides of the equation gives you a much more complete picture of how a bike actually rides.
What Linkage Does
At its core, Linkage models the kinematics of a bike’s suspension linkage — the physical pivot points, links, and levers that connect the rear wheel to the frame. By defining these points in 2D space, the software calculates how the rear axle moves through its travel and how the leverage ratio changes at every point. This matters because leverage ratio determines how the shock is compressed at different points in the travel, which directly affects small-bump sensitivity, mid-stroke support, and bottom-out resistance.
The software also calculates anti-squat (how much the suspension resists compression under pedaling forces), pedal kickback (how much the pedals move when the suspension compresses), and the rear axle path (the arc the rear wheel follows as the suspension cycles). These kinematic properties interact with geometry — a bike with progressive leverage and high anti-squat will feel completely different from one with linear leverage and low anti-squat, even if their geometry charts look identical.
The Bike Library
One of Linkage’s most useful features is its extensive library of pre-modeled bikes. Hundreds of mountain bike models are available with their suspension pivot points already mapped, so you can pull up a bike, run the simulation, and compare it against any other model instantly. This makes it possible to compare the suspension kinematics of a Specialized Stumpjumper against a Trek Fuel EX not just on geometry numbers but on how their suspensions actually work through the stroke.
Why Suspension Kinematics Matter for Geometry
Static geometry — the numbers on a geometry chart — describes a bike at one specific point: fully extended, unweighted, with the rider off the bike. The moment you sit on the bike, the suspension compresses into its sag point and the geometry changes. Head angle steepens, BB height drops, wheelbase shortens, and reach decreases. How much these numbers change depends on the suspension kinematics.
A bike with a progressive leverage curve will resist deep travel and maintain geometry closer to its static numbers through most of the riding. A bike with a linear or degressive curve will sag deeper, changing its effective geometry more dramatically. This is why two bikes with identical static geometry can feel different on the trail — their suspensions alter the dynamic geometry in different ways.
If you’re comparing bikes on our geometry pages and two models look nearly identical on paper, their suspension kinematics may be what separates them in practice. Tools like Linkage help visualize that hidden dimension.
Key Metrics in Linkage
Leverage Ratio Curve: Shows how the mechanical advantage between the wheel and the shock changes through the travel. A progressive curve (leverage decreasing through travel) resists bottoming out; a linear curve provides consistent resistance throughout.
Anti-Squat: Expressed as a percentage, anti-squat describes how much the chain tension counteracts suspension compression under pedaling. Values above 100% mean the suspension actually extends under pedaling force. Most modern trail bikes target 100-130% anti-squat at sag.
Axle Path: The arc traced by the rear axle as the suspension moves through its travel. A rearward axle path helps the wheel move backward over square-edge hits, improving traction and comfort.
Pedal Kickback: How much the cranks rotate as the suspension compresses. Lower pedal kickback generally means a more comfortable pedaling feel on rough terrain.
Getting Started
Linkage is available as a desktop application for Windows. The free version provides basic functionality, while the full version unlocks advanced simulation features, the complete bike library, and the ability to design custom linkages. Visit Linkage’s official site to download and explore.
If you’re more interested in understanding geometry than suspension design, start with our mountain bike geometry guide and learn how to read geometry charts. For riders who want to go deeper into the engineering behind how bikes handle, Linkage is an invaluable tool for connecting the dots between frame geometry and suspension performance.
Frequently Asked Questions
Is Linkage free?
There is a free version with limited functionality. The full version requires a license and unlocks the complete bike library, advanced metrics, and custom design tools.
Can I compare different bikes in Linkage?
Yes. The bike library includes hundreds of models. You can load any two bikes and overlay their leverage ratio curves, anti-squat values, and axle paths for direct comparison.
Does Linkage work on Mac?
Linkage is a Windows application. Mac users can run it through Boot Camp, Parallels, or other Windows virtualization solutions.