How to ride an electric unicycle - understanding the dynamics

[Chriull]

7 hours ago, mrelwood said:

Once the tilt reaches ~45 degrees, the wheel is programmed to turn off the motor. Although, by that time the rider has already fallen or bailed.

 

1 hour ago, Smoother said:

I like your description over all, but are you sure about this part (quoted)?  I know wheels shut off past 45 degrees sideways, but I have never heard of 45 degrees forward.

Me neither. Would imho also make no sense to "artificially" limit forward/backward tilt. As long as the motor still has "capabilities" the wheel should at least try to balance the rider - no matter how much the pedal is tilted.

[erk1024]

8 hours ago, mrelwood said:

If you are wondering about wether the pedals stays level and the rider just tips over because of a lost footing, no, that can’t quite happen on level ground.

You might’ve seen extreme accelerations in videos. While the rider’s CoG is well past the front of the pedals, if the rider would start to fall off the front of the pedals, all his weight would be at the very front edge of the pedals. The only way for the wheel to stay level in general is to fight the tilt with acceleration. It wouldn’t stay upright if it would accelerate any less than what is required to catch the rider’s lean.

If the wheel doesn’t have the power to accelerate fast enough, it will tilt forwards, pedals and all. This is when and how the crash by an overlean happens. Once the tilt reaches ~45 degrees, the wheel is programmed to turn off the motor. Although, by that time the rider has already fallen or bailed.

Sudden obstacles are another matter though. If the wheel hits a pothole, sinks in sand etc, the speed of the wheel is reduced even if the wheel is succesful in staying upright. But there is nothing to slow down the forward leaning rider. The rider is not prepared and the ankles are loose, so the rider doesn’t get his weight on the front edge of the pedals in time. No weight = not enough acceleration, so the rider falls on his face while the wheel stays upright.

That's exactly the info I was looking for. This is super interesting! Makes sense. Who knew there could be so much subtlety in one motor connected to one wheel. 

[mrelwood]

10 hours ago, Smoother said:

I like your description over all, but are you sure about this part (quoted)?  I know wheels shut off past 45 degrees sideways, but I have never heard of 45 degrees forward.

Easy enough to try, so I did to make sure. My 16S turns off when tilted past about 45 degrees backwards/forwards while the wheel is running.

Didn’t try with the MSX as it’s a bit heavy to be manhandled for me at this very moment. Plenty exposed tire also makes the test slightly more challenging.

Edited April 23, 2019 by mrelwood
K

[Smoother]

On 4/23/2019 at 10:58 PM, mrelwood said:

Easy enough to try, so I did to make sure. My 16S turns off when tilted past about 45 degrees backwards/forwards while the wheel is running.

Didn’t try with the MSX as it’s a bit heavy to be manhandled for me at this very moment. Plenty exposed tire also makes the test slightly more challenging.

How did you get a wheel that is switched on to tilt  45 degrees forwards and backwards?

[mrelwood]

10 minutes ago, Smoother said:

How did you get a wheel that is switched on to tilt  45 degrees forwards and backwards?

Lift up the powered wheel with both hands (one on the handle, other below the upright pedal) and quickly turn backwards/forwards, before the wheel gets to the tilt-back speed.

Bonus point: While still holding the wheel in air, slowly rotate the wheel towards neutral. At approximately 45 degrees the motor literally kicks back in and accelerates to cut-off speed as it is trying to enforce the tilt-back.

[Smoother]

Well, whadoyano!  It worked.  Not every time.  The wheel took off like a scalded cat more than once before I could trick it. Almost lost a few finger into the bargain.  It's really not that easy to pick a wheel up and violently tilt it back/forward before the motor ramps up to speed. If you try this do as KING SONG says and "Be caution".  Get a piece of you between the tyre and shell when the wheel shoots up to top speed and your next stop WILL be the hospital.

I did notice that the motor did not re-engage until the wheel was righted to about 20 degrees, which is the same result I get tilting it left and right (KS16S) and if the tyre is on the ground, it doesn't shoot up to cut off but simply performs its slow righting procedure until the unit is level again.

[mrelwood]

 

Quote

I did notice that the motor did not re-engage until the wheel was righted to about 20 degrees, which is the same result I get tilting it left and right (KS16S) and if the tyre is on the ground, it doesn't shoot up to cut off but simply performs its slow righting procedure until the unit is level again.

20, 45... all look the same from the tangled position I was at the moment!  Of course there must be some offset between disengage and engage, didn’t think about that.

When my 16S did the rush to tilt-back, the wheel was still spinning. I suppose if the wheel has stopped, the firmware understands the situation and doesn’t do anything hasty. While the wheel is at speed I think it is good that the motor comes back online as fast as possible, just in case there’s still a rider aboard to be saved.

Edited April 25, 2019 by mrelwood

[Liam9653]

A lot of useful information thanks! Only recently began to ride, having read it before could avoid injury.

[erk1024]

Hey new riders (like me) get yourself some serious boots!

So I think something that's not emphasized enough is that as a new rider, you really need some ankle protection (to go along with the helmet, wrist guards, elbow pads and knee pads). It's all too easy to lose balance, step off the wheel, and have a pedal whack you in the ankle.

I thought that my high-top hiking boots were going to get the job done. But as you can see from the pictures, that level of protection wasn't nearly enough. So if you don't want your ankle to turn the color of the wrong kind of rainbow, you should get some serious boots. I found some motorcycle boots for $90 that should do the trick. Just make sure they can go over you knee and shin guards (or only wear knee pads).

I did look at full motocross boots, but I was worried that they would be too inflexible in the ankles.

 

Edited May 4, 2019 by erk1024

[mrelwood]

Those boots will surely protect your ankles and shins very well. The main issue with motorcycle shoes in general is that they don’t usually offer any shock absorption at the (mid-)sole. Not an issue for riders with knees of steel, but I had to stop using them because of that.

For the learning phase that doesn’t of course matter much.

[Smoother]

Ah yes, the ankle biter from hell, also known as the EUC. I thought the problem was covered quite well.  Maybe it's spread out all over the place. I found 27 pages of links to posts with the word ankle.  Not all deal with ankle protections but the oldest one that does is from May 2015. Still, I'm sorry you got hurt.

[erk1024]

I wanted to make sure there was a bigger warning in the learning thread, as I thought I was OK with hiking boots.

 

[Mike Sacristan]

I hit the back of one of my ankles 3 weeks ago and it has now finally healed.
Just a flesh wound.
I remember wearing boots and high tops for a couple of days and then I just started wearing whatever.

I guess I need to sever a tendon before learning my lesson.

[stephen]

I wear sketchers spongy sole and grippy 

[erk1024]

I think as a beginner, you should gear up like a Star Wars Stormtrooper even though you're going slow--because you're just THAT incompetent. Then once you've attained a certain skill level, you can tone it down a bit (for reasonable speeds). For high speeds (e.g. 35+ mph) then it's back to Stormtrooper, regardless of skill level. There is a graph I saw about this somewhere. Can't remember where. So many web pages viewed in EUC research...

[Smoother]

1 hour ago, erk1024 said:

as I thought I was OK with hiking boots.

yep you did say that, and one would assume that would be enough, in fact that's all i wore, but i did have small sponges in the tops of my socks because the KS14C has blade-sharpe  edges right where my ankle bones are. Possibly the sponges took some whacks for me.

You're right to emphasize that more protection is advisable.

[Smoother]

1 hour ago, stephen said:

I wear sketchers spongy sole and grippy 

That sounds like "suspension" of a sort to me. 

[tessa25]

I chose Merrell tactical boots 8" high.

[erk1024]

41 minutes ago, tessa25 said:

Merrell tactical boots 8" high

Good idea. I'm sure they're lighter, breathe better and have better cushioning in the sole.

 

Edited May 5, 2019 by erk1024

[kasenutty]

By the time you break those mad max boots in, you won't need 'em anymore  

[jhonheb]

I think that unicycle and normal bike riding is different part.

[Mono]

20 hours ago, erk1024 said:

It's definitely worth while to quickly adjust reflexes and always stay out of the pedals and wheels way when stepping down or running off. This has the additional advantage that the wheel cannot serve as a stumbling block when running off.

I have "protected" the sharp edges of my handle with the standard baby edge cushion protection. This works well when the wheel is just falling over and I want to mitigate the impact with the leg, or in cases like these:

I use any shoes for riding, but when I started, I got painful blue marks just from mounting. To prevent these I used soccer shin protectors for a few months.

Edited May 5, 2019 by Mono

[erk1024]

WOW. I know it's been said on this thread a zillion times, but it's really something to experience firsthand.

There is a speed at which the wheel becomes super stable. That speed is a lot higher than I would have expected. It shouldn't be too surprising, it happens on other devices that rely on balance (scooters, bikes, etc.) But on a kick scooter, that speed is low, maybe 6 kph. I don't know what the speed is on the wheel, but it's much higher. I think @meepmeepmayer mentioned 15kph? Does it change depending on the diameter of the wheel?

Riding becomes effortless, and you're not flailing around. SO MUCH FUN! I wonder if this is what you guys mean by "one day it just clicks". Maybe click'ing is just having enough skill and confidence to get up to this magical speed. Then once you know it's there you don't spend any time in the wobbly speeds, but instead accelerate to the stable speed as quickly as possible. No doubt, over time you naturally build more proficiency at lower speeds as well, but it's not longer a priority, and the learning process can move on to turning and ... other challenges.

[meepmeepmayer]

I don't think there's a specific speed. The faster, the more stable one is thanks to conservation of angular momentum But I guess for every skill level there's a speed where you get stable, and the more experienced you are, the lower it is.

36 minutes ago, erk1024 said:

Riding becomes effortless, and you're not flailing around. SO MUCH FUN! I wonder if this is what you guys mean by "one day it just clicks". Maybe click'ing is just having enough skill and confidence to get up to this magical speed. Then once you know it's there you don't spend any time in the wobbly speeds, but instead accelerate to the stable speed as quickly as possible. No doubt, over time you naturally build more proficiency at lower speeds as well, but it's not longer a priority, and the learning process can move on to turning and ... other challenges.

I think that's very true. If you can stand on the wheel while loosely holding on to a wall/pole with one hand and maybe move it back and forth on the spot, you can ride if you're fast enough.

The "clicking" might also be when you start the quick rotations to stabilize you (like a bicycle's front wheel) instead of shifting weight between the feet and bending your upper body. But now that you say it, the combination of confidence and high enough speed is probably also a big part of it.

I always recommend to new riders to not be afraid and accelerate to 15-20kph right away. Riding faster is much easier than riding slower.

Maybe that's where you got some specific number from. It's my estimate for what I did on my first ride, accelerating every time I felt it got too instable, and probably that was meandering between 15-20kph.

Edited May 5, 2019 by meepmeepmayer

[erk1024]

18 minutes ago, meepmeepmayer said:

But I guess for every skill level there's a speed where you get stable

That sounds right to me. And so maybe there is a crossover point where your balancing skill is increasing and your speed naturally goes up, and then all of a sudden you feel really stable. I think people's natural inclination is to slow down when they start wobbling, and that makes the situation progressively worse. So it's good that you encourage people to try to go faster.