Trailing-link fork

The trailing-link fork is the front suspension that Vespa made famous and that the original Bajaj Chetak and LML scooters copied. A single rigid tube drops from the steering head on one side of the wheel. At its bottom is a pivot, and from that pivot a short link runs backward to a stub axle, so the wheel trails behind the pivot. A coil spring, with a hydraulic damper inside it, is mounted between the link and the fork tube. Piaggio's modern Vespas still use it, in a slightly updated single-arm form.

• The front tyre meets a bump and the link swings up and back around its pivot.
• The coil spring compresses and the damper controls the movement.
• The short link means the wheel moves in an arc, so suspension travel is limited, typically less than on a telescopic fork.
• Under braking the brake torque rotates the link downward, so the front dips more than a telescopic fork would; the pivot position is chosen to keep this dive moderate.

The single-sided design is why a Vespa's front wheel comes off like a car wheel, with one nut and no fork leg in the way, and why the original scooters carried a spare. The rider notices a soft, slightly bouncy front over small bumps and a tendency to dip under braking. The layout is cheap and compact and keeps the steering light on a small wheel, but it cannot match a telescopic fork for travel or stiffness, which is why almost every other scooter has moved on.