Suspension Geometry Calculator
Adjust rake angle, fork offset, and wheel size to calculate trail length and see how your front-end geometry affects handling character.
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What Is Trail?
Trail is the horizontal distance between where the front tyre contacts the ground and the point where the steering axis (extended from the fork) meets the ground. A larger trail creates a stronger self-centering tendency and higher-speed stability; smaller trail makes the steering lighter and more responsive at low speed.
How Rake and Offset Work Together
Rake is the angle of the steering axis from vertical. Increasing rake increases trail and stability. Fork offset (also called triple clamp offset) works in the opposite direction — increasing offset reduces trail. This is why manufacturers can fine-tune handling feel independently from frame geometry: a sportbike might have a steeper rake combined with more offset to achieve the desired trail figure without compromising chassis stiffness.
Trail Formula
Trail = (wheel_radius × tan(rake)) − (fork_offset / cos(rake)). The wheel radius is half the tyre diameter, calculated from the rim size only (the tyre section height is not included in this simplified model, which assumes the geometric contact patch reference).
Changing Geometry on Your Bike
Lowering the front suspension reduces rake and trail, quickening the steering. Raising the rear has the same effect. Aftermarket offset triple clamps (typically 5–10mm more or less offset than stock) are a popular way to fine-tune track-day handling without altering the frame or suspension travel.