Vision Wheels – How the PRA System Works With Our Hubs

In this Product Inside, today we are talking about the PRA system on Vision wheels. Vision wheels are often described as fast and smooth rolling wheels. Many of the pro riders, triathletes and amateurs using our Trimax and Metron wheels, are absolutely in love with the feeling of the smooth rotation, the fast rolling and the perfect cornering of our wheels. How can they roll so well? Well for that we need to say thank you to the PRA system. PRA stands for Preload Reduction Assembly. It’s an innovative and clever lightweight system that we use on our hubs. It allows us to create the perfect amount of lateral preload on the bearings. Inside this hub body we have sealed bearings, that we produce in our own facility with high precision both inner and outer races. They sit into a perfectly machined hub body where the tolerance is very low and this allows us to obtain the perfect parallels between the bearings. Thanks to the PRA they work always with the perfect amount of lateral preload. This keeps them extremely smooth and long lasting. Now we will show you step by step how to perfectly tune the PRA. The first step is to loosen the retaining screw on the PRA collar. The second step is to fine tune directly the open PRA collar until you reach the perfect bearing preload. The third step is to retighten the retaining screw. The forth step is to verify that the wheel spins smoothly and without any lateral play. So this is the PRA, an innovative lightweight, easy, simple system that together with uncompromised quality, top notch aero design, artisan hand built construction makes Vision wheels some of the fastest wheels on the market. To know more about Vision wheels product range please visit

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