Wheelbase: the case for short decks

In this post, I want to make the case for a turn to shorter decks. First, I explain why long decks are redundant, then I list the advantages of short-wheelbase decks and finally I attempt to answer exactly how short decks should/could become.

Introduction

The idea that a long wheelbase is necessary for so-called “LDP” skateboarding is cemented by the marketing of “LDP-specific” decks and fostered by forum communities (the familiar vicious circle). The idea probably started with the discipline itself, which most likely was conceived as an offshoot of slalom, with the twist that it’s on a longboard (clues: Smith et al., 2009) (I’ve written a bit more about this here). The entire longboard category is on shaky ground. Longboards are hard to justify when their full length is not utilized by the riders. Except for freestyle skateboarding (or longboarding), it seems unnecessary to make decks longer than needed by the rider to stand on*.

*Please note, I argue against their presumed necessity. Some people like to use long decks for the trampoline-flex. Some people find long decks aesthetically pleasing. Some people even bolt trucks on surfboards. I’m not arguing against any of that.

Turning and wheelbase

Front truck at a constant 30,64° turn, with the wheelbase and the rear truck turn changing simultaneously so that the turning radius remains constant at 101,28

“What about turning,” I hear you ask. The main point here is, there is no adequate justification for singling out wheelbase as the defining parameter of a deck’s turning character. All three variables: front and rear truck angle and wheelbase, are sufficient and necessary to determine the turning radius of a skateboard, when tilted a given amount. If you’re not convinced wheelbase does not uniquely determine a skateboard’s turning characteristics, please have a quick look here, here and here (or here)*. In light of this, I can see no advantages for a long wheelbase for non-freestyle skateboarding (except personal aesthetics, or extreme flexing). What about the advantages of shorter wheelbases?

*It’s crucial this point is understood, otherwise the following will sound fanciful. It’s basic euclidean geometry from school. Please, if in doubt, show this to someone who was better at math before reading on.

Advantages

One of the advantages is that a short deck helps reduce wheel-lift. I talk about wheel lift in more detail in this article. Here, I just want to point out an issue that arises with the distribution of the rider’s weight on a long wheelbase. Most people stand towards the front of the deck, using the nose of the deck as reference for foot placement. This means there is less load at the back of a long deck and this tends to induce wheel-lift, even when the rear truck is relatively soft. Conversely, on a short deck the rider’s weight is distributed evenly over the trucks, thus helping resolve issues with wheels lifting off. A balanced front and rear truck stiffness is nevertheless required.

A second advantage is that it increases traction and reduces involuntary wheel-slide. When the rear is unweighted it slides more easily. By unweighting the rear, the rider initiates controlled voluntary or involuntary slides (Loaded Boards, 2018).

Third, short decks are obviously lighter. They’re easier to push uphill, easier to carry around when on foot. This is actually the most important advantage and it baffles me why manufacturers who care about performance still haven’t figured this one out.

Fourth, they are more eco-friendly. Less material used, less chemicals, less energy. The part of a long deck the rider doesn’t use represents waste.

Finally, in my subjective opinion, they look cooler. If it’s a topmount, it belongs more firmly in the skateboard category and it might even suggest a more skilled rider (if you care about how you look). But also a bracket platform might be aesthetically more pleasing if it has the size that is actually needed by rider and not more.

Size

How short exactly should decks be? Obviously a few centimeters at the edges are needed for safety, but perhaps needless adornments such as pointy noses could be removed. More decisively, the effective foot platform (EFP) must be reduced down to only the length that is needed by the rider. The effective foot platform should be as long as the rider’s stance and not longer (and I might argue that more experienced riders could try conforming to shorter decks still, in view of the aforementioned advantages).

In my case, an EFP of around 65cm would suffice, as I would never spread my legs more than 60-65cm. What about the rest of the population though? Time for some field research! I did a survey in three online longboard communities, in which I asked one simple multiple choice question to obtain the maximum amount of responses: “How wide is your stance?” (as a fraction of the respondents’ height – i.e., a dimensionless ratio; for more details, follow links below). As I do not know the size of the population (i.e., number of longboarders worldwide), I cannot have any measure of confidence of how representative of the distribution in the population the findings are. Additionally, since these three forums are for english-speaking users, many non-english speakers are already out of the sample. However, there is no logical reason why the answer to this question was biased in any way by the country of origin or internet habits (do Spanish skaters ride with their legs closer together? do twitter users ride wide?). Therefore, by the nature of this simple question and with respect to it, I think it’s a strong case that the sample was indeed truly random. One objection that responses to this question might have been biased is on my choice of possible responses: a) < 0.32; b) 0.32-0.34; c) 0.35-0.37; d) 0.38-0.40; e) >0.40. It is conceivable that riders below 0,32 or over 0,4 felt excluded and decided not to participate. In any case, the findings are as follows:

Links to the survey: facebook, reddit, tapatalk.

I think it’s logical to expect that below 0,32 and above 0,4, if I had offered a wider spectrum of choices, we’d find fewer and fewer riders. In other words, it seems like a good guess that this corresponds to a typical bell-shaped curve. Why would there be other peaks beyond those limits? Let me explain this point more. If there is no reason to assume this measure of stance has more than one particular value around which riders converge and if also, given the responses, we can guess that the value around which most riders converge is somewhere within 0,35-0,37, it seems reasonable to assume that my small sample is consistent with a population that follows a bell-shaped curve with a peak somewhere around 0,36.

If that sounds too haphazard to you, dear reader, then I’d still be happy if you could agree it’s a reasonably good guess that the vast majority of riders (around 80%) have a stance <0,4. Because that’s the main point I want to make.

How much room do these riders need on the deck? To answer this, we must also ask: how tall are they? Well, this is how tall:

Source: Our World in Data

A popular deck for an average male with a wide stance would then have an EFP of 0,4 · 1,7m = 68 cm. A popular EFP for an average female with a narrow stance would be 51cm. Conversely, a 70cm EFP could accommodate even a two-meter-tall skater with the universally used stance of 0,34. Therefore, I contend that manufacturers ought to focus on making decks with EFPs from 55cm to 70cm, perhaps with extra choices beyond these limits.

Conclusion

The reader should not overestimate the forcefulness of this contention. I’m not suggesting we ban long decks! I merely state that in view of their advantages (against wheel lift and slide, weight, waste), short decks ought to have a far larger market share than they currently do, while manufacturers should seek to improve their mechanical attributes to improve their suitability for LDP, cruising, downhilling etc. At the same time, marketing long decks should not be fallaciously based on their purported turning character, but on their possibly desired aesthetics or flex.


References:

Loaded Boards. (2018). How to Slide and Ride your Longboard. Loaded Boards.
Smith, J., Harms, J., & Morro Skateboard Group. (2009). Lives on board. Morro Skateboard Group.

I want to thank: Zipzit, whose comments helped me shape the section about the limitations of my small survey; Peters, for making a point on weight distribution; Apricot_Traditional, for comments on an earlier version; Donatas for commenting on the general argument.

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