I should preface this by saying the point of this thread is to understand longboard mechanics related to speed and stability. I am going to try to word things in kind of a scientific manner, so I apologize if it comes off as offensive in any way.
I suppose at the most basic level, my question is: What physical properties of a longboard result in what people refer to as stability?
I feel like there’s two parts to this.
One: What is it that we define as stability? In practice, it seems like stability means the board is more resistant to sudden, and undesired changes in direction ie speed wobbles.
Two: The ways I’ve heard of people attaining stability include changing hanger width, bushing configuration, baseplate angles, and deck shape. Why do changing these things affect stability the way they do?
@RipTideSports from what I can tell you seem to be somewhat of an expert on this topic, so I’m interested to see what you have to say about this.
Its been discussed here a few times, but i don’t think wider hangers are more stable. You have more leverage and therefore small movements become more amplified on a wider hanger. Enter speed wobbles.
I believe that a longer wheelbase would help with stability tho.
I think wider hangers are less stable as well. The narrower the hanger is, the more I feel in control. Though it might look silly, I also like narrower hangers in the front. Part of this is because it’s hard to fit drivetrains on narrow hangers. Part of this is because I need more control of the front.
Loose trucks. You should be able to lean way over, probably all the way into wheelbite. IMHO of course. Tight trucks cause me to have less control. Also, if you hit a large bump or rock and your truck goes all cattywampus, loose trucks will right themselves so fast without you actually doing anything. A tight truck will take longer to correct – and while it’s correcting, be steering out from underneath you, causing an off-balance moment.
And of course, the most well-known way to gain stability imho is to have a steeper angle in the front. Combine that with a riding style of putting most of your weight and nearly all of your steering input into the front truck, and it means you’re more in direct control. However, more offset angles aren’t as good at lower speeds where the 4 wheel steering actually seems to help the carve a lot. But once you get into high speeds, the offset angles help a lot.
The thing to remember is almost all speed wobbles are in the rear trucks.
@Cyanoacrylate I would call stability not being able to get the board to wobble or feel like it has any slack or oscillation at normal speeds. Then once you start factoring in road conditions or lack thereof I think it gets much more complicated.
Agreed. From a physics standpoint it should create a wider more stable base but if the trucks aren’t tracking perfectly in line due to bushing differences, truck angles, etc I feel like it would just make the fight to correct worse.
Wheelbase for sure though. Even swapping to my few-cm-shorter-wheelbase mtb deck the other day felt super odd. Same trucks and bushings.
Lower rider height (tuck) in general will stabilize you as well.
Less wind resistance
Lower center of gravity
More preloaded muscles ready to respond
Not sure if I agree on this one personally. Maybe it transfers differently to mtbs but too loose trucks and a bump will cause a big wobble. Tighten it up just right and the same bump gets corrected by the bushings faster and doesn’t throw me around as much. Tighten too much and you go into the grass when you can’t make a turn though so like everything, there’s a balance.
I think it’s also important to discuss what makes a longboard unstable compared to other vehicles. This paper actually covers it in pretty good detail in the intro section.
While it’s well-known that adding riser (deck height) decreases stability, which I do agree with, I feel like it’s often exaggerated. Riser certainly makes the board feel different but once you get used to it, I feel it only adds a marginal amount of instability. Of course, within reason. I’m not talking about adding 30cm of riser. Maybe 4cm maximum. 1-4cm.
If given the choice between narrow trucks with a riser, or wide trucks with no riser (often a choice you’re faced with to avoid wheelbite) then I will usually choose narrow + riser every time. It feels more stable to me.
I feel like stability = confidence, and that’s why i do agree on the looser trucks. Because i feel less in control with stiffer bushings.
I do think this is also a big mistake “builders” make, they want the biggest baddest, stabelest baddy out there, while in fact these machines take a lot of time getting confident and thus stable on. You can’t just ride away and get 100% confidence, resulting in many many boards that are wayy too stiff and people not satisfied with them.
Its like a motorcycle, you need to spend a lot of time on it before you can go fast well and get everything out of it. That’s why i always recommend new people to ride with good bushings tightened just below their comfort zone.
Google fu’d this, and please excuse the copy paste because it aligns well for this application I reckon:
(added punctuation where needed)
“the property of a body that causes it, when disturbed from a condition of equilibrium or steady motion, to develop forces or moments that restore the original condition”
It’s like something that seems self righting and easy to control. Not twitchy, or squirrelly or prone to speed wobbles.
I’m no expert but believe that:
Split angles help increase stability, by altering steering bias.
Lower CoG helps
Longer Wheelbase helps by reducing turning radius.
Wider hangers shouldnt affect it, but in practise they seem to increase leverage from bumps and also perhaps allow bumps to affect one wheel more than both (compared to narrower hangers) meaning more chance of bump induced instability.
Keen to hear @RipTideSports comments. It seems that bushings act like suspension in a way. Compression and rebound speed and dampening are crucial in determining ride feel. Too soft and slow, means poor return to centre and slushy, too firm - poor responsiveness. Too fast rebound - twitchy.
I always thought narrower hangers were more stable because they had a faster response time – ie: it’s faster to fling the wheel backward if it’s closer and doesn’t have to travel as far. But idk. I just know narrow hangers feel super responsive and more stable and self-correcting to me.
I picture it as you’re holding a ball attached to a stick, and you want to turn the stick 15 degrees very, very quickly ---- do you want the ball close to you or far away? It’s going to be much slower to turn the stick if the ball is far away.
It’s closer in distance, but not rotationally.
Inertia for moving wheels further probably has an impact (comparing extreme examples). Narrow slalom hanger vs hyper truck.
Edit - fuck those Rogue precision trucks on your link look nice, Brian.
Here’s my interpretation. Given the same baseplate angle, same bushings, and same tightness, two trucks of different hangar width will require the same amount of lean and force applied by the user. From a user input standpoint, they should feel decently similar (ignoring inertial effects).
Both trucks require the same applied torque on the hangar to move it x degrees. But since your wheel is further away from the point of rotation, a pebble of a set size will apply a higher torque on the hangar and as a result move it further. As simple as that. Every bit of road will affect the hangar more.
I dont think that is true either since if you hit a pebble with short trucks its the same travel backwards, just the force on a different spot since a lot of travel on long trucks is not a lot of travel in the bushing , resulting in the same movement there.
As somebody who likes to go fast (like 80km/h) and not crack the eggs I bought from grocery stores, I’ve invested a large portion of my short esk8 career into fighting the wobble. To respond to this
Most of the parts above contribute to turning, and I personally think that the easier a board is to turn, the easier you’ll get a wobble on it. Stability and agility are of an f(x) = -ax + b relationship.
In my experience:
Longer wheelbase allows a larger turning radius, thus more stable.
Longer hanger width makes the board easier to turn, thus more unstable (but I’m not saying slalom 7" trucks are a great idea, foot width 10" trucks are the smallest trucks esk8s should have IMO). However, wider wheels make it more stable from contact points relative to the ground perspective, so there’s a sweet spot somewhere there where the trucks aren’t too narrow due to the pursuit for wider wheelbase and not too wide neither preventing the wide wheelbase from providing easier turns.
Double barrel bushings are harder to turn when compared to a barrel + cone set up, and double cone bushings are the easiest to turn with. So if you want stability, Db barrel > B+C > Db cone. Using the right washer helps too, never ever use disk washers, always use cup washers. disk washers don’t compress the bushings enough to utilize their functionality.
Baseplate angles have a significant impact on your turning radius, however in the case of stability, due to the most stable stance is weighing heavily on the front trucks, I just kept the front trucks in the stock RKP config (50 degrees) and used a 30 degree rear truck. A steeper baseplate allows for a smaller turning radius while a shallower baseplate allows for a larger turning radius.
Deck shape doesn’t really affect much about turning radius, but a drop or even double drop deck will allow you a lower centre of gravity thus a more stable ride, and less prone to wobbles.
I’d just like to talk a little bit about my 80km/h set up here (theoretically it could hit higher speeds but I don’t trust cloudwheels enough to go that fast yet, maybe when I get my wheel hubs. Even hitting 80km/h was a dumb idea tbh when using cloudwheels smh…)
I have a boardnamics 270mm hanger setup with the landyachtz Evo 40" deck, which naturally gives the front a steeper angle and the rear a shallower angle. I then proceeded to give the rear truck even more angle to make it around 15 degrees level to the ground. Although my hangers were wide ASF, the baseplate angle, long wheelbase, stiff 99A Duro double barrel bushings, and the Evo drop deck, combined gave me a board that I took 80km/h on. I wasn’t getting any wobbles whatsoever, and I’m glad that I’ve done my fair share of research before going that fast lol. Had a really bad speed wobble on my previous street build which merely went 44km/h tops but still was quite deadly, imagine getting one at 80km/h now.
Another thing to touch on to avoid wobbles is the ride stance. The basic principle of a speed wobble is that your rear truck turned too much and your body kept self-adjusting for the slight changes and because the momentum changes are too frequent to keep up, your tiny auto-adjusted-turns oscillate into rapid, intensifying carves till you crash. In order to not turn your rear trucks easier, you need to lean your body forwards to get the weight on your front trucks instead of the rear trucks, and that’s literally it. Don’t back off at high speed or a big hill, because that’s when you’ll lean back, compress rear bushings, which destabilizes itself and get you wobbling. JUST SEND IT and you’ll be completely fine.
I mean, I’ve hit 60 with a dkp setup with stiff bushings, so that’s why I thought more turny a board is the easier it is to wobble.
and I completely agree with this. My Evo build literally can’t corner properly at lower speeds and it could get kinda annoying occasionally when I’m downtown and just wish to zig-zag around.
