Wheel travel from shock travel, or the reverse
A shock's stroke and the wheel's actual travel are rarely the same number — the suspension's motion ratio scales one into the other. Solve for whichever you don't already have.
Getting a number you can act on
- 01Choose which direction to solve
Checking how much wheel travel a shock you already have provides points at solving for wheel travel. Specifying a shock for a target amount of wheel travel points the other way.
- 02Enter the known figure
Shock stroke from the manufacturer's specification, or your target wheel travel from suspension geometry or ground clearance requirements.
- 03Enter the suspension's motion ratio
The same figure used throughout the suspension calculators here — wheel travel divided by shock travel, typically below 1.0.
- 04Read the amplification factor alongside the result
This is simply 1 divided by the motion ratio, and it shows directly how much more the wheel moves per unit of shock movement — useful for sanity-checking whether a shock's stroke is adequate.
What the calculator is actually doing
Nothing here is proprietary. If you would rather check it by hand, or explain it to someone at a counter, these are the same expressions the tool evaluates.
wheel travel = shock travel ÷ motion ratioBelow a motion ratio of 1.0, wheel travel exceeds shock travel by the amplification the geometry provides.
shock travel = wheel travel × motion ratioThe same relationship reversed, for specifying a shock to hit a target.
Why checking this matters before buying a shock
A shock's stroke is a fixed mechanical limit — run out of travel and the shock either bottoms out internally or the suspension's other components take the impact instead, neither of which is a good outcome.
Because motion ratio scales shock stroke into wheel travel, the same physical shock provides completely different amounts of usable wheel travel depending on where it's mounted in the suspension geometry. A shock that's perfectly adequate on one motion ratio can be genuinely undersized on another, even with an identical stroke rating.
This is exactly why aftermarket coilover and shock specifications matter more than they might seem to at first — a shock swap that changes the mounting geometry, and with it the motion ratio, changes how much wheel travel the same physical shock actually delivers, sometimes in a direction that catches people out.
Wheel Travel Calculator FAQ
How do I calculate wheel travel from shock stroke?+
Divide shock travel by the suspension's motion ratio. A 3-inch shock stroke at a 0.6 motion ratio provides 5 inches of wheel travel.
What shock stroke do I need for a target wheel travel?+
Multiply the target wheel travel by the motion ratio. For 6 inches of wheel travel at a 0.6 motion ratio, you need a shock with at least 3.6 inches of stroke.
Why does wheel travel exceed shock travel?+
Because most suspension geometries have a motion ratio below 1.0, meaning the wheel is positioned with more mechanical leverage than the shock — the wheel moves further than the shock shaft does for the same suspension motion.
Standards and references behind these figures
The arithmetic on this page is fixed, but the boundaries and conventions around it come from published standards and manufacturer guidance. These are the documents they come from, so you can check them rather than take them on trust.
01Ford Performance — dynamometer testing and engine performance tech tipsManufacturer guidance on dyno correction and how quoted power figures are arrived at.↗02The Tire and Rim Association — standards filing (NHTSA docket)TRA has been the US standardising body for tire and rim interchangeability since 1903; this filing sets out dimensional practice.↗Geometry is exact; your specific suspension may not match the assumption. Motion ratio, in particular, changes through the suspension's travel on most real cars rather than staying constant — these formulas use a single fixed value, which is a reasonable approximation near ride height and a worse one at the extremes of travel. Measure your own motion ratio directly where precision matters.