Rear hanger width: does it matter?

“Get a narrow rear” is often given as advice in internet communities for LDP. Is this a relic of the dark ages of skateboard geekery, or is there a valid LDP/slalom-related reason behind it?

A reason given is heel strike: a narrow rear eliminates the possibility the rider’s foot will strike a rear wheel while pushing. That is of course a valid reason, but it is not specific to LDP. It is just common sense.

Another reason given is a narrower hanger offers more traction. This is more promising because in LDP (and slalom) traction is an issue. Why would a narrower hanger offer traction then?

After discussing this with people on the internet, I found that a surprising amount of them seem to think there are differences in the force acting on/by the ground, from/to the skateboard+rider for different hanger widths (this pertains both to the discussion about traction in this paragraph, and about stability further down, so please bear with me for a moment); therefore the amount of static friction differs. There are many ways to show this is absurd, one of which is that for it to be true, we would have to assume the existence of extra amounts of force from the rider that appear only on certain hanger widths and not others. It’s important for the reader to remember that a skateboard can in principle be ridden and balanced without bushings. It must never be treated theoretically as a rigid four-wheeled vehicle, but as a two-wheeled vehicle. It balances on the centers of the two axles.

Another reason given is that a “[n]arrower hanger/axle will flex less, allowing more traction due the the wheel’s contact patch remaining in “contact” with the pavement better” (skully, 2020). Does the hanger/axle flex and would that be noticeable in the relevant scale? I would argue it doesn’t flex at all. Truck hangers (made of aluminum) generally look pretty stiff to me. Axles are made of steel which from what I know flexes more than aluminum, but only a small portion of the axle is exposed; only the part that receives the wheels. Regardless of the length of the axle, manufacturers usually build hangers that support the axles on every width of their truck lines and leave the same length axle segment exposed to receive the wheels.

I do see, however, a reason to have a valid sensation of less traction with the road when skating on a wider truck. That’s the play between the hanger and the baseplate. On regular trucks, on which the hanger is supported in place just by bushings and a pivot cup, we all know there is play. A longer hanger makes that play more noticeable (i.e., that play is more pronounced on the wheels) and has a greater impact on traction. A clear solution to this is bearings supporting the hanger in place, and not merely the bushings (see “disclaimer” further down).

But then, why would “get a narrow rear” be an LDP (or slalom) specific recommendation? Besides, it appears narrow rear trucks are also gaining popularity in downhill skateboarding. Is there a discipline that would benefit from a wider rear truck? Are there any advantages whatsoever? Some seem to argue a wider rear offers stability. I’ve read the wikipedia entries on traction, weight transfer etc and at first glance they seem to corroborate this: “[b]ias to one pair of tires [note: due to load transfer when accelerating or cornering] doing more “work” than the other pair results in a net loss of total available traction.” So one can mitigate this “by increasing the wheel spacings. Increasing the vehicle’s wheelbase (length) reduces longitudinal load transfer while increasing the vehicle’s track (width) reduces lateral load transfer. Most high performance automobiles are designed to sit as low as possible and usually have an extended wheelbase and track” (Wikipedia). However, the above is for cars. Scientists refer in this case to perfectly rigid bodies, which still undergo “load transfer.” On skateboards, the rider is free to shift position relative to the board. A skateboard behaves like a two-wheel vehicle in that respect and it cannot be considered a rigid body in the above sense. Therefore, a wider rear truck does not offer more stability and there seem to be no other advantages across any skateboard discipline.

I see no valid reason why a narrow rear truck is an LDP (or slalom) specific recommendation. Neither does truck width help reduce wheel-lift in any meaningful way (see my explanation here). The idea that a narrow rear truck is a universally applicable recommendation is surprisingly unpopular, but there is no convincing evidence that it is anything other than a common sense thing to do, which truck manufacturers ought to have adopted across the board.*

References:
Wikipedia on Weight transfer
Facebook group: LDP
Tapatalk group: pavedwave
Changing Angles article on wheel lift
Image credit: https://shop.ccs.com/skateboard-buyers-guide/skateboard-trucks

Disclaimer for beginners:

We don’t know for sure how much (if at all) wider hangers offer less traction. It’s just a theory I read in social media and I can only grant that it makes sense to me. But I haven’t personally felt any difference between different widths and I would doubt anybody really has, despite any claims otherwise. However, it’s with the most confidence that I tell you that by far the most important factor for traction at the back is foot placement (weight distribution). [Think of how slides are initiated] So instead of considering truck widths, consider deck lengths and really avoid long “longboards” (for more on that, here). Another factor is wheel softness; obvious.

*Obviously, wheelbite can be an issue for dropped decks, but if truck makers had indeed realized the above, they would have been explicit about offering wider hangers only for dropped decks. I’m sure they have no clue though.

4 thoughts on “Rear hanger width: does it matter?

  1. My reasoning behind narrow rear is still more traction. If we take zero degrees rear truck and real world big soft rear wheels it’s easy to see why this is the case.
    Some part of leaning force twists the truck, another part squishes wheel leap (outer leap of the inner wheel of the turning circle). For narrower hanger width the squish will be more pronounced because of greater lever (platform with to truck width). And more squish means more contact area to the pavement, consequently more traction.

      1. I’m absolutely sure about my point, wheels are not hard but elastic. It’s not boundary conditions just before wheel lift, but much longer condition during any hard turn.
        Easy to see: if we take a big peace of thick glass, spray some water on it and put a board with big soft wheels and narrow axle at maximal lean. Picture form underside will show different amount of contact surface – more on inside leap and less on outside.

      2. It’s not so much that I disagree, it’s that it’s unclear to me where you’re starting and where you’re going with this. Do you have any objection on the article, or you just want to say that the only reason why people think narrow hangers have more traction is because the wheels are getting squeezed more? Because I don’t agree with that, but I also don’t have enough from your theory to tell you exactly what I disagree with. Certainly I see no reason why wheels would be squeezed more: how much a truck tilts depends only on its bushings, not on its axle length, because force on the ground on each wheel must remain the same, otherwise you end up with various logical inconsistencies (consider extremes for your arm-lever model); but even if it didn’t remain the same, the sum of the four wheels can’t possibly be more, nor less, than rider weight plus muscle push, but always equal, otherwise the rider will sink in the ground or fly in the air (please read again the text above, fourth paragraph).
        And even if, for argument’s sake and if all of the above were false though they couldn’t be, the wheels did get squeezed more, that wouldn’t mean that there would be more traction because of the larger contact area anyway: this doesn’t check out either (as per theory, only force and friction coefficient matter). Perhaps I’m missing something here. But thanks for your great input, this is valuable content!
        Looking forward to your next comments and your picking a nickname! 🙂

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