Progressive Fork Springs Hyperpro | Triumph Street Twin 900

You fit progressive fork springs first to gain in comfort and road holding. Unlike a standard spring with a constant pitch, a progressive spring stiffens gradually, which absorbs small imperfections better while handling big hits. The result is a smoother ride, better stability and greater line precision. It is one of the most effective suspension upgrades for road use on a neo-retro motorcycle.

A Hyperpro progressive spring is wound with an asymmetric pitch, meaning the gap between coils varies on purpose along the spring. This design, driven by the Hyperpro suspension management program, gears the dynamic profile towards comfort. In practice, the fork stays supple over small bumps and firms up under heavy loads. Hyperpro springs also come with a lifetime warranty.

This kit (Hyperpro ref SP-TR09-SSA025) is designed for the Triumph Street Twin 900, model years 2016 to 2019. It has a frame number restriction: it applies to Street Twin 900 models with a VIN before 914972 or 917474. Check your frame number before ordering. If you are unsure about your version or model year, confirm compatibility with us.

Fitting is a full fork oil change, best entrusted to a workshop: 1) Remove and drain the fork tubes. 2) Replace the original springs with the Hyperpro progressive springs. 3) Fill with the supplied oil (SAE 15). 4) Carefully set the oil level to the mark specified by Hyperpro (oil level 120 mm, air gap) in each tube. 5) Reassemble the fork. Fitting is original-type, with no permanent modification to the chassis, but it calls for method and tools.

Yes, fitting the springs requires a fork oil change. The oil is supplied in the kit: 1 litre of SAE 15, whose grade was chosen by Hyperpro to match the springs. This grade must not be changed. For subsequent oil changes, it is recommended to use Hyperpro oil of the same grade. The crucial point remains respecting the specified oil level.

Progressive springs improve comfort, stability and line precision. They reduce the jolts and vibrations transmitted to the wrists and forearms, which is welcome over long distances. They can also reduce braking distance by up to 20%, thanks to better absorption of kinetic energy. The bike gains in composure as well as in dynamism.