A very frequent question in online skate communities concerns the “appropriate” or “recommended” wedging; in essence the angle of the trucks. It comes either from beginners setting up a new board, or advanced skaters who purchased a new truck. This question brings an avalanche of apocryphal inaccuracies. I’ve read that all TKPs should be wegded to have their KP vertical, that a specific brand requires more wedging than another despite having the exact same initial pivot axis angle, that certain concept trucks (like this one) actually require de-wedging to turn more; and nobody ever mentions wheelbase and its role.1 The list of mystical claims is endless.
But how do we decide which angles our trucks should be wedged to? In this short post, which is addressed mostly to beginners, I propose a decision process, for anyone to adopt or adapt, that is neither simpler, nor more complex than necessary. I explain the rationale behind it with as much clarity as possible.
The front part of the deck is what the rider uses as reference for foot placement and stance. It is in this sense the part of the board that the rider rides. In slalom and LDP, the rider’s weight is what propels the board forward, so the front truck angle is both crucial and personal. It seems that collective experience has shown that 60°± x° (0<x<5) is the appropriate range for the front pivot axis angle. How come 60° is the most recommended front truck angle for slalom applications? I do not know2. Whatever the reason may be, I take the front pivot angle to be a hard constraint (the independent variable, if you prefer). For so-called surf-skate applications it could go up to 65°, for high speed slaloming it could go down to 55°. It is worth noting also that, if the board is dropped, the rider has to stand further back from the front truck, than if it were a top-mount board. A higher front angle will offset this distance and make the rider feel as if riding closer to the truck.
The second constraint is the wheelbase: the rider needs to be able to stand on the deck comfortably. As that is ultimately dependent on the rider’s own body, personal preference and, at any rate, we all probably already own a deck, we will have to work with what’s available. I consider this also a hard constraint. (For more on the overall length and the effective foot platform of decks, as well as a rider stance survey, look here and here.) It is worth mentioning that many decks are already, or can be, drilled for more wheelbase options. (There’s something to be said here about traction and distance between feet and trucks, but I don’t want to expand on this now and it is anyway irrelevant to truck angles. What is relevant is that, all other things being equal, longer wheelbase options result in longer turning radii. But let’s see this in conjunction with the rear truck angle.)
The rear truck angle is directly related to wheelbase (see here, or here). Wheelbase and rear truck angle should be considered the parameters determining the turning radius and therefore top speed in given conditions (for more on this, look here). The front angle is naturally also responsible for that, but I leave it out of this consideration; we’ve tackled it earlier. I take it as necessary that the rear truck angle is flexible, because it is not constrained like the front angle is. It is the dependent variable, if you will. Let’s then also assume we already have a deck (therefore the wheelbase variable is fixed). How do you decide what the rear angle should be? You could start with a reasonable angle (I have talked about ways to make proper decisions on this: here in rough, rule-of-thumb manner and here with more accuracy). What is “reasonable,” exactly? That’s arbitrary, but the forums are in this case a good resource. Look up your wheelbase and see what angles people use for that. Then control: if your slaloming (pumping) is too squirrelly, decrease the angle; if you can’t even start slaloming, you must increase it. It literally doesn’t get simpler than that. If you already have a preferred front/rear angle and wheelbase combination, but now you are using a new deck, you must use the function linked above to acquire the exact same turning radius from your new board.
Let me know if I missed something, or if I must rephrase something for clarity.
1. These fallacious claims are rooted on misconceptions about two fundamental skateboard principles: first, the axle turn (for a given tilt of the deck) of each and every single-pivot truck is determined only by the truck’s pivot axis angle; second, the turning radius of a skateboard is determined by all of the following: a. its front pivot axis angle, b. its rear pivot axis angle, and c. the wheelbase. Please check the linked posts if you’re not following.
2. I can make a few guesses, but I do not want to write them down, as there’s enough empty theorizing in skateboard forums and I’d like this blog to have either well-established, solid evidence, or at least disciplined, substantiated observations; i.e., things unlikely to require editing in the future. I accept the front PA angle range tentatively as is and without proof, with a mind to explore possible explanations in the future.