Pivot Cups and Tubes Explored

 

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Truck pivots are finally receiving the attention that they deserve in the skateboarding world. Their effect and contribution to the overall feel and control cannot be overstated so let’s take a look at what they do and why they are important.

For the sake of this article, let’s establish two categories of pivots, two categories of trucks and two types of pivots: Trucks can be categorized into two broad classifications, reverse king pin (RKP) such as Aera, Caliber, PNL Strummers, Buzzed Beefcake, Paris and traditional king pin (TKP) such as Independent, Theeves, Gullwing Chargers, Ace and Krux.

RKP trucks exhibit a fairly straight-forward action when they turn, the imaginary line drawn from the nose of the hanger pivot through both the base plate and the center of the diameter of the king pin provides the axis of rotation for the hanger.

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TKP trucks on the other hand exhibit a much more complex movement that is very dependent on the truck’s design geometry. It is characterized by both rotation and angulation at the pivot point. Pivots can also be categorized into two types, a cup and a tube.

The cup is simply a closed-ended style where as a tube is open-ended. Since they are both acting as a pivot, the material used should be lubricated, which is why we use our self-lubricating WFB compound.

Pivots in Action

Depending on a truck’s design, pivots can be used to accomplish several things. They are used for the obvious - to provide a pivot point for turning - and they can also provide an end point and act as a “thrust” bearing, keeping the king pin centered in the hanger. Without an end point, all the responsibility for positioning the king pin in the center of the bushing seat now falls on the bushings, so the lack of a pivot end point front loads the bushings to support the hanger position.

With a well-defined bushing seat, this is usually not a problem, but in ill-defined or nonexistent seats, if the pivot tube or cup is not also acting as thrust bearing, the area behind the pivot can crash into the base plate damaging both the hanger and the baseplate. This movement can also cause the bushings to come out of the seat causing a loss of control!

The thrust aspect is much more obvious in TKP trucks due to their design geometry that more evenly splits the responsibility to carry the load between the bushings and the pivot. The durometer of the pivot defines how much feedback you receive from the trucks. The harder you go, the greater the feedback.

The softer you go, the plusher the ride, the more forgiving they are and the feedback is now minimized. We find our WFB 96a to be the perfect combination of feedback and performance

Stock versus Aftermarket and Homemade Pivots

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We have found that most pivots that come with a set of trucks do not perform as well as homemade and aftermarket pivots. There are exceptions in the precision truck category but for the most part, stock cups should be replaced if you are interested in high performance from your equipment.

Stock Advantage: Inexpensive and readily available locally.

Stock Disadvantage: Low performance, universal styles (one size) so there are a lot of compromises here.

Homemade Advantages: High performance and made specifically to your specifications and requirements.

Homemade Disadvantages: You need access to the proper tools and the knowledge to accomplish the task. You also need a source of high quality materials which are expensive and not readily available.

Aftermarket Advantages: High performance pivots. A lot of time and effort goes into the design and material selection. RipTide supplies self-lubricating WFB rods to other companies so they can offer WFB as one of their options for machined pivots. RipTide uses WFB exclusively for molded pivots.

Aftermarket Disadvantages: High performance costs money and good aftermarket pivots are not available everywhere on a local basis.

In conclusion, pivots are finally being recognized as a very important component that affects the overall performance of any skateboard system. For a modest outlay of cash you can transform a sloppy performer into a precise, smooth turning machine.