Conventional steerings on motorcycles comprise either telescopic forks or upside-down forks, both of which are widely used on bikes these days. There is, though, a third steering assembly (hub steering) that are usually considered taboo or pure witchcraft by the uninformed. Today, we’re here to shed some light on the differences between the former and the latter, and how a bike benefits from either type.
To begin with, let’s get the basic working of a fork out of the way. A motorcycle fork comprises a spring and a damping unit inside. The springs offer compression, while the dampers, with the help of oil, control its velocity. In essence, both telescopic forks and USD forks have almost similar working components.
Telescopic forks are the most common solution for modern budget bikes but aren’t perfect design solutions. The fork angle and leverage tend to exert powerful forces on the yoke or steering head of the chassis, thereby creating a demand for heavy, bolstered frames. As a result, the bike dives forward under heavy braking forces, causing the steering geometry to change and reduce suspension travel which deals with bumps, all the while maintaining traction.
Granted, the setup is quite orthodox and has its flaws, but it’s cheaper to manufacture and easier to maintain in the long run.
Unlike conventional steerings, a hub steering provides a complete vertical steering axis for the front wheel instead of an angled one. This makes for more direct and responsive steering.
The Bimota Tesi H2 uses such a unique contraption. It’s also one of the reasons why Bimota earned its name. To elaborate, a wheel hub pitches back and forth on a central pivot, pushed by two large steering arms actuated by the handlebar.
To break it down, the handlebar connects to the front steering or swingarm via various complex linkages. There’s a pull-and-push rod on either side of the center-hub connected by a fixed arm that helps steer the bike. The setup also has a second pair of rods, which are static and ensure the axle stays level with the rest of the bike.
A centre hub steering system does not dive as much as a conventional telescopic fork. In fact, it pushes braking forces more efficiently back into the chassis instead of transferring bending forces on a pair of forks. It offers an almost supernatural ride experience with huge amounts of confidence be it in braking performance in mid-corner or on sharp corners.
While a hub steering has its clear advantages, it is costlier to manufacture. Also, the complex system is more expensive to maintain and can only be fixed by an expert hand.