Mountainboard/pneumatic wheel longboard: channel- vs. kingpin truck geometry theorycrafting

Hi all,

I was thinking about a proper truck design for a DIY pneumatic wheel longboard truck lately and there, I had some weird findings when comparing (spring- or MTS) channel trucks - which are usually used in mountainboard builds - with conventional (reverse-) kingpin longboard trucks:

Other than kingpin trucks, channel trucks (such as 1 or 2) seem to have significant amounts of rake - about 15-25mm. Channel truck manufacturers state, that these channel trucks are more stable at higher speeds than conventional trucks. But according to various longboard truck guides, rake increases maneuverability but decreases stability (see here)? In this guide, it can be seen that positive rake lowers turning at low angles (“expo” in steering), which to my feel would INcrease stability at higher speeds since slight angular variations in neutral position do not affect turning that much.

It is true that the spring- and damping mechanism is different, but in either truck system, the steering mechanism is essentially the same: rigid axle rotates around a tilted rotation axis.

Interesting side note: These kingpin trucks for mountainboards also seem to have significant amount of rake (about 15mm).

So what’s the truth about rake and why is that much difference between channel- and kingpin trucks?

What about “split rake” - for example front much rake (and high truck angle) and rear little to no rake?

What would be most suitable in a pneumatic wheel longboard with about 280mm hanger width and 6.5" tires (-> longboard/mountainboard “hybrid”) for up to 50km/h (30mph) primarily onroad without stability problems? Significant amount of rake like channel trucks or little to no rake?

I’m also curious about this for a setup that you were looking for. What did you end up doing?

I bought some MBS ATS.12 trucks for the front and designed a custom rear “powertrain axle” with about the same amount of angle and rake as the front trucks. Since I am still waiting for production of my rear axle aluminum parts, I can’t say if it is working well or not up to now.

Well, im not much into steering geometry, but im sure if you look up some @Flexboardz or @MoeStooge posts, some useful info should be there.

Some good basic understanding can be bought from these videos (though might not refer to spring trucks):

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