What is speed wobbles of electric skateboard? - Ecomobl Electric Skateboards USA

What is speed wobbles ?

Here is Mark Choi’s explanation of electric skateboard speed wobbles:

Speed wobbles are due to a physical phenomenon that occurs in many, disparate systems, and can not be “solved” entirely, only significantly dampened, no matter what many different companies claim about their equipment.

ALL skateboards are subject to speed wobbles, both powered and unpowered. As are many other devices, such as Onewheels, EUCs, scooters, even shopping carts.

They are a physical phenomenon where, when the device goes above a certain speed, they become more and more susceptible to the board violently oscillating back and forth, uncontrollably, oftentimes resulting in severe crashes where the rider is thrown from the board, possibly leading to significant injury as well as damage to the board.

Pretty much every experienced rider has experienced then at some point.
They can be reduced to an extent by hardware modifications or changing the way one rides, but, because they arise out of a physical phenomenon inherent in the mechanics of the boards, they can not be eliminated entirely.
Additionally, riders can learn to make adjustments to how they ride to respond to them when they occur.

A lot has been written by many people online about speed, wobbles age how to prevent them, unfortunately, almost all of it wrong. Speed wobbles arise out of a physical phenomenon called the Hopf bifurcation. In systems affected by the Hopf bifurcation, the physical parameters of the system create a specific threshold, below, which, the system remains stable in a static equilibrium. But above that threshold, they transition to a state where they enter a dynamic equilibrium, where, instead of remaining in a stable state, they oscillate back-and-forth between two extremes.

This effects numerous other physical systems, which have their own Hopf bifurcation points where they transition from stable to oscillating states, from skateboards to EUCS, to shopping cart wheels, to population dynamics in predator/prey relationships in biological ecology
The way this affects skateboards, is that when they are riding slowly, the static, stable equilibrium state is one in which the rider is riding straight forward with the wheels parallel to the deck, and the trucks perpendicular to the street. But above the Hopf bifurcation point, the board transitions to a state where it is no longer stable in static equilibrium, riding forward with the wheels in a straight line, but rather, is now becomes stable in an oscillating equilibrium, where the wheels turn to the left, and then turn to the right, and back again, and the trucks alternately angle towards the deck on the left and then back toward the deck on the right, causing the board to steer quickly left and right then left again back-and-forth, violently shaking the rider until he or she can either regain control of the board, or is thrown off entirely, at high speed.

This is made even worse by inexperienced riders because their autonomic nervous system, which is attempting to keep their body upright, responds to this violent oscillation in exactly the wrong way, responding to the boards veering to the left by instinctively attempting to turn back to the right, but doing so at exactly the wrong time after the board has already transitioned to turning to the right on his own. As a result, the rider’s actions only serve to amplify the turning of the board to the right. When the rider senses that the board is turning too quickly to the right, they again instinctively attempt to correct it by veering to the left, but again correct just as the board is already steering to the left on its own, thus, the rider amplifies the oscillations that began because of the Hopf bifurcation in exactly the way that makes these oscillations become amplified. And the faster the rider goes, the more violent the oscillations become, the harder they become to control, and the more likely the rider is to be thrown off the board.

Experienced riders are able to regain control (or never lose it in the first place) through a number of techniques, but also, after significant riding experience, can avoid them altogether, riding through and beyond the Hopf bifurcation point, where they basically train, retrain, or untrain their nervous system so it stops overreacting to the oscillations under their feet, and instead merely let’s the board oscillate under their feet and “rides them out“.

 

Ultimately, you don’t counter speed wobbles by modifying your board hardware, you reduce or eliminate speed wobbles by training your brain through practice on how to ride fast.

I am in the process of writing a paper on the subject.
Whew!
Below is Dan Myers opinion
Mark Choi I agree with you, which is why I advocated for more experience and better riding practices as the solution rather than hardware.
Yeah I’ve found what Mark said to be the case. Speed wobbles are the rider making fine steering corrections without realizing. Small shifts in weight become large movements at the wheel as speed increases. You can stiffen the turning springs and make the board resist your own movements with allen key preload adjusters, or swapping for stiffer springs but the best way I’ve found is to ride as fast as you feel comfortable with in open areas away from people and try going faster at a rate you’re comfortable with until you can hit the speeds you want in a stable manner.

How to avoid speed wobbles

Rey Suprem opinion

Shift your body weight forward the faster you go.., you need that matrix lean.

  

Mark Rockshock opinion

Rey is right.
Basically: more weight on the front axle, always!
With an AWD, there is a compromise with the weight shift – depending on the terrain.
Green or red springs (it’s like with Matrix, the blue or the red pill 😉 ): it’s a question of your weight.

I weigh (too much) almost 100kg with luggage and protection. The green springs are recommended on asphalt so that I can carve stably at around 50 kmh / 32 mlh. Yes, you can carve very precisely with the M24 and the green springs at maximum speed. No problems. The board is very stable.

But when I go off-road, or am on a BMX track or MTB trail, then the red springs go in FRONT so that I can steer much more agilely. You can feel that clearly.

But if I have the red springs in and I’m itching to go full throttle on the asphalt, then there’s only ONE thing:

Never just drive straight ahead! Always move the eSk8 left/right so that NO speed wobbles can occur! and as already mentioned, always put more weight on the front leg.

A good example of this: a beginner snowboarder on the tow path into the valley (narrow path, slow ride). He gets caught and falls flat on his face BECAUSE he only went straight ahead. If he keeps moving and uses the path in width (or at least a little), he won’t get caught.

 

and I could give the following example:
a downhill skater has only enough pressure/weight on the back leg for the board to just have grip. This means that the front axle is the steering and at the back it only keeps the track. This means that the downhill skater can also “loosely” turn the board sideways to brake, controls the board via the front axle and remains stable at high speeds

 

This is how Olivier Crescence solved speed wobbles

I completely removed “kind of” wobbles by switching from metal spring to TPU 85A bushings on rear truck. Made a huge change in how the board (Telum BA 4WD) absorb shocks and react to various terrain (specially asphalt and dirt road ). That said, experience (body posture) makes you more aware of risks of wobbles at hight speed 🙂

 

John Reese opinion

Change your springs. I ride green up front and red in the back. If you have springs.

 

Beth Dye

If I tight the “trucks” to not get speed wobbles?

 

Paul Marshall

In regards to Beth Dye’s inquiry about how to tighten trucks on the M24, no one commenting understands and they are completely missing the point. Every skateboard, electric or not or even this M24 with full suspension needs to be adjusted to the rider’s preference, weight and riding style. I told her how to adjust the truck springs on the M24 by the following. Use the long handled orange tool, to poke small holes through the grip tape, like I did in this picture. Screw clockwise to tighten or counterclockwise to loosen the screws. She can also tighten the shock absorbers by hand, using the top riveted knobs. I used the old Ecomobl red & black grip tape – sand paper on my new M24, as seen. Jusr for your information.

Otherwise, she will need to access those screws on the deck of the board to replace with red, blue or green springs, again, depending on how tight she wants them to be.

Post time: 06-14-2024