[robert-brown]

Roller skating plate trucks are similar to skateboard trucks.

Kingpin angle affects cornering ability. Kingpins at higher angle from vertical corner more sharply, so skaters doing figures tend to prefer more vertical kingpins than dance skaters, who want to be able to do deep curves. For instance, kingpin angle is the major difference between Snyder Super Deluxe and Imperial plates.

Durability is a serious consideration for roller skating kingpin angles. It's painful when a kingpin breaks and more common with less vertical kingpins, so most skaters doing freestyle will choose a plate with kingpins closer to vertical. Roller skate plates also often have a "jump bar" connecting the two trucks to decrease the chance that a kingpin will break when a jump is landed. Sometimes even a jump bar breaks.

[atoav]

In skateboarding people tend to use angled riser pads to adjust the kingpin angle. As a side effect these riser pads can (ever so slightly) absorb hard shocks and decrease the chance of a wheel-bite (when your wheel comes into contact with the wood of the deck and stops you apruptly). This is not necessary with most longboards as they usually have a higher clearance, or even cutouts at the sports where wheelbites would occur. In street skateboarding the tradeoff is a little different, because the area where wheelbites occur are just next to the area "the pocket" you utilize for nearly all flip tricks. Also taking wood away there would have a negative impact on stability so street skaters would rather live with wheel bites than sacrificing wood area there – or as mentioned use the stiffest pushing you can find, use riser pad, tighten the trucks or similar.

[gabereiser]

As a previous skateboarder, the sweet spot is having full weight on a corner and having about 5mm of space between the wheel and the board. Wheel diameter also plays into the equation. Smaller wheels are used for looser KPT truck setups to reduce the wheel bite mark while increasing the truck turning capability. Risers further this difference. A standard park/street setup is different than, say, a downhill setup or what you find at your local department store. 48-52mm wheels instead of 56-58mm.

Longboards use larger wheels and wider trucks to clear the board of any wheel bite. Some even cut out that area of the board. For skateboarding, you need that area for stability, flip tricks, and landings.

The physics of it all is what’s so awesome about it.

[xodjmk]

About Zero people use riser pads in modern skateboarding. Nobody cares about wheel-biting either, even with loose trucks. if you wheel-bite and fall, you failed to land your trick. The goal is to land 'bolts', as kids say. (Source - any skate video)

[robert-brown]

One more thing ...

Good quality skates have pivot pins whose length is adjustable. I don't know if skateboard trucks generally have this feature.

You tighten and loosen the pressure on the kingpin rubber bushings by shortening and lengthening the kingpin in order to adjust resistance for cornering. When you do that, you also need to be able to adjust the length of the pivot pin. Otherwise, lengthening the kingpin results in a pivot pin that's not resting properly in its cup. You want it just touching, not floating out of the cup or exerting a lot of pressure on the cup.

[robert-brown]

A couple more details ...

Good quality roller skate truck pivot pins end in a spherical ball and the pivot pin cup on the truck is also spherically machined. There's no bushing in the cup.

[bze12]

How exactly does the jump bar affect impact resistance? Distributing the force evenly I assume?