How to ride an electric unicycle - understanding the dynamics

[Hanger18]

Hi. For what its worth from a total newbie. I've owned my Nicola Plus for 8 days. Did the usual fence/wall/rail thing for the first few days. Then moved on to grass football pitch mainly to save my wheel’s casing from gravel rash.. Spent 3 days of pure frustration managing to ride just a few feet at a time before falling. I nearly gave up. In desperation. I wrapped my wheel in rubber car mats and duct tape. So I could practice at work on a hard surface… EUREKA ! ! Within 10 minutes I was riding across the car park. Today, 2 days later, I’ve just ridden 4 miles around my local park only falling twice. Just to test something, I had another go on grass, and still cant get going and stay on. So with my limited experience I would suggest learning on tarmac is much easier.

Dave.

[meepmeepmayer]

Yep, grass is officially evil

If you want to ride on grass, be relaxed and pretend the grass isn't even there. Just ride and force the wheel along with you.

 

[rcgldr]

On 8/11/2021 at 10:20 PM, rcgldr said:

A third method for moderate speed is to twist the upper body into the turn, then follow with the legs. However, this is a form of counter-steering, which is not good if the rider is already leaning due to falling, since initially it increases the unwanted leaning even further, and it delays the reaction to correct for a fall. Some riders use a combination of body twist and till steer (if balanced and not falling). In the videos I've seen, most recommend using tilt steer as the primary way to turn, unless the speed is so slow that pedal scrape is an issue, in which case yaw-steer is recommended.

 

On 10/19/2021 at 7:18 AM, Eucner said:

To my understanding this is a combination of yaw and tilt steering.

I've seen a couple of how to ride EUC videos that mention body twisting, but I don't think it's a good idea for beginners. For low speed, arm flailing (flail left to steer right and vice versa) seems to be the most instinctive way to steer into fall, such as this 3 year old:

https://www.youtube.com/watch?v=z9YiHu5HJ6o

or depending on the EUC, at some speed it becomes mostly stable, so the rider doesn't have to do much for balance. On my V8F, it is stable around 8 mph.

Body twisting without tilt steering will yaw steer an EUC in the "wrong" direction, which is what I was calling counter-steering.

I've seen videos of body twisting with tilt steering used to make sharp turns. While approaching a sharp turn, tilt steer into the direction of the approaching turn and twist upper body so the EUC keeps going straight despite the tilt (building up twisting momentum), then for the actual sharp turn, twist the legs to catch up to the now twisted upper body to yaw steer the EUC in addition to tilt steer. 

 

Edited November 23, 2021 by rcgldr

[meepmeepmayer]

Neat video about countersteering on a bicycle. Works the same for EUCs.

This is short and explains how you need to countersteer on a device that relies on balance, just like EUCs do.

This also applies to keeping the balance on a EUC at very low speeds. Essentially you countersteer back and forth constantly by twisting the wheel under you, and ride in a squiggly line.

[Rywokast]

5 hours ago, meepmeepmayer said:

Neat video about countersteering on a bicycle. Works the same for EUCs.

This is short and explains how you need to countersteer on a device that relies on balance, just like EUCs do.

This also applies to keeping the balance on a EUC at very low speeds. Essentially you countersteer back and forth constantly by twisting the wheel under you, and ride in a squiggly line.

wow, i never realised that lol.. i guess when you ride its just completely intuitive, i always thought it was purely gyroscopic... i wonder if eucs have a much stronger gyroscopic effect than bicycles because of their mass and the fact that its all concentrated in a small package, because the counter steering doesnt apply on them, and also you can ride in a perfectly straight line, that would also explain why its harder on an euc to go slow is because of a diminished gyro effect, but even at 5 kph i have no problem riding in a straight line, but it just took years of practice

[Tawpie]

54 minutes ago, Rywokast said:

i wonder if eucs have a much stronger gyroscopic effect than bicycles

If I understand the physics correctly, you can/do trigger precession by weight transfer on the pedals on a moving unicycle... more weight on one pedal will want to yaw steer the wheel toward the weighted side without tilting it. I have no idea how large this turning force actually is, but suspect it's relatively small and that unconscious counter steering is the predominant way we turn.

[Rywokast]

1 hour ago, Tawpie said:

If I understand the physics correctly, you can/do trigger precession by weight transfer on the pedals on a moving unicycle... more weight on one pedal will want to yaw steer the wheel toward the weighted side without tilting it. I have no idea how large this turning force actually is, but suspect it's relatively small and that unconscious counter steering is the predominant way we turn.

no idea.. once again its all just intuitive.. i can ride while playing on my phone, nearly falling asleep, drunk.. its like walking, i dont think about it at all, so it would be interesting to be able to see a video face on to see if there is any of this going on, because if it does happen its completely unconscious... but the thing is, when you push an euc it can also go by itself for a long time like a bike, except that it has no steering mechanism or anything at all like he pointed out in the bike video, which leads me to believe again that the gyroscopic forces are much stronger in an euc

[mrelwood]

13 hours ago, Rywokast said:

which leads me to believe again that the gyroscopic forces are much stronger in an euc

They probably are stronger at faster speeds, but they are not what’s keeping a runaway wheel upright at jogging speeds or less. Any tubular tire has two (or was it three) self-correcting forces. The EUC tire being usually much wider than in a standard bicycle, these forces are much stronger as well.

A gyroscopic force is not self-correcting or self-balancing. It actually resists any corrections, even the necessary ones. For example, gyroscopic forces resist getting the wheel back upright after a turn. Since this is never an issue even on top heavy EUCs, it seems that the gyroscopic forces are actually pretty minor next to the other forces in play.

[Eucner]

1 hour ago, mrelwood said:

Any tubular tire has two (or was it three) self-correcting forces. The EUC tire being usually much wider than in a standard bicycle, these forces are much stronger as well.

I would like know more about this. The crown radius can create a self-correcting force, but it doesn't work universally in every geometry and it is weak. Is this one of the forces? What are the others?

[mrelwood]

2 hours ago, Eucner said:

I would like know more about this. The crown radius can create a self-correcting force, but it doesn't work universally in every geometry and it is weak. Is this one of the forces? What are the others?

It’s best if you try to find the original discussion, as I’m not an expert in this. It was about the forces that make the EUC turn. I think the thread was started by “rcglrd” or “mhpr262”.

At least one of the forces was called camber force/effect. Another was the conic/cone effect due to the outer edge of the tire having a smaller radius. So when the wheel tilts to the side, it turns in that direction like a rolling cone.

 Sorry about the sherlockholmesy answer, but I don’t remember more precisely atm! 

Edited December 13, 2021 by mrelwood

[Eucner]

39 minutes ago, mrelwood said:

It’s best if you try to find the original discussion, as I’m not an expert in this. It was about the forces that make the EUC turn. I think the thread was started by “rcglrd” or “mhpr262”.

Thanks, I tried. I only found multiple posts from @rcgldr about turning, but not about tire self-correcting forces. From mhpr262 I didn't find anything concerning this matter.

54 minutes ago, mrelwood said:

At least one of the forces was called camber force/effect.

Oh yes, there is a camber thrust. This is resisting movement (like  gyro effect). It is not self-correcting. The reset is minimal after turning force is taken away.

59 minutes ago, mrelwood said:

Another was the conic/cone effect due to the outer edge of the tire having a smaller radius. So when the wheel tilts to the side, it turns in that direction like a rolling cone.

Neither is this self-correcting.  A bicycle is having multiple self-correcting forces from it's mechanics. A bare tire is more limited in this respect.

[mrelwood]

2 hours ago, Eucner said:

Neither is this self-correcting.

Sure it is. The wheel starts to fall left -> the cone effect turns the whole wheel left -> the weight of the wheel wants to go straight -> wheel stays upright.

 At least that’s what I meant by a self-correcting mechanism.

[Eucner]

4 hours ago, mrelwood said:

Sure it is. The wheel starts to fall left -> the cone effect turns the whole wheel left -> the weight of the wheel wants to go straight -> wheel stays upright.

 At least that’s what I meant by a self-correcting mechanism.

This cone effect only slows down falling. It can't straighten the wheel up again.

[Tawpie]

On last nights cruise I paid very close attention to what I do when I 'turn' on the S18 and indeed, when I'm going straight and want to turn, I actually do counter steer—not because my brain says 'counter steer', because my other parts just do it for me. It's subtle, but definitely there. No video evidence though.

Likewise, when carving, the reversal of carve-direction happens after a teeny bit of over steer... slightly late on pulling out of the turn sets me off balance in the other direction so I'm all set to go.

[.....]

Think bicycle and simply ignore that there's no front wheel. If you know how leaning and turning works on a motorcycle or bicycle, you neednt think about how it works on an euc. Same physics involved.

[Tawpie]

11 minutes ago, ShanesPlanet said:

If you know how leaning and turning works on a motorcycle or bicycle,

I knew this in my head, but hadn't ever bothered to really demonstrate it to myself—the video above was amusing and really brought home the point.

I still want to get a better idea as to why my 16X tram lines as much as it does, and why it insists on yanking the wheel into the slope of a sloped surface (ride in a mtn bike track that is u-shaped and narrow—if you're not dead center at the flat bottom, the wheel wants to climb the sides and won't go straight). It's the tire, but 'why'? The S18 with a knobby doesn't do this—which is really strange to me.

Edited December 14, 2021 by Tawpie

[Eucner]

1 hour ago, Tawpie said:

I still want to get a better idea as to why my 16X tram lines as much as it does, and why it insists on yanking the wheel into the slope of a sloped surface (ride in a mtn bike track that is u-shaped and narrow—if you're not dead center at the flat bottom, the wheel wants to climb the sides and won't go straight). It's the tire, but 'why'? The S18 with a knobby doesn't do this—which is really strange to me.

In your case the tires contact point to the ground is on side. It is the same point when turning. The cone effect turns your wheel up. Wheel center of gravity is still in the middle. The distance from center line to the tires contact point creates a moment to the opposite direction. The tire and ground geometry dictates which of these two forces is greater and gives the direction to your wheel. Tire with large crown radius is likely to go down and small radius up. Tire pressure plays also role here.

Here you can see the definition of crown radius.

[Tawpie]

dang cones. I guess though, it's comforting to see that the physics work pretty much as expected. Still, I don't like the "this side of the trench, overcorrect, that side of the trench, overcorrect" underdamped result. Practice practice practice until the muscles handle this by themselves like they do starting an intentional turn. Brain is just too slow.

Thank you @Eucner!

[mrelwood]

6 hours ago, Tawpie said:

I still want to get a better idea as to why my 16X tram lines as much as it does, and why it insists on yanking the wheel into the slope of a sloped surface (ride in a mtn bike track that is u-shaped and narrow—if you're not dead center at the flat bottom, the wheel wants to climb the sides and won't go straight). It's the tire, but 'why'? The S18 with a knobby doesn't do this—which is really strange to me.

The difference between a knobby and a solid street tire is huge in this regard. The first knobby I tried I had to switch out very quickly, since the turning on it was just horrible. Yes, it didn't follow slopes at all either, but still, it was way too much. The CST C-186 was a good bit better, but still not something I like very much.

Since the knobbies are so different in their turning (and slope following) tendencies than regular EUC tires, I believe that the knobs change the game and the crown radius is no longer what determines the behaviour. Since the Heidenau K66 doesn't have this behaviour at all despite having a highly figured tread, I don't really know if it's the soft and tall knobs or the placement of the knobs that mainly cause the issue. Following that, I'm not sure which of the turning forces is the one that's lacking (the most) on a knobby.

[rcgldr]

On 12/12/2021 at 5:53 PM, Eucner said:

Oh yes, there is a camber thrust.  Neither is this self-correcting.

 

On 12/13/2021 at 1:35 AM, Eucner said:

This cone effect only slows down falling. It can't straighten the wheel up again.

Terminology: camber thrust is related to deformation versus lateral loads (applies to bikes, cars, ...). Camber effect is the cone effect. 

Assume no relative foot movement by the rider, so that the EUC is leaned the same as the rider, and a small lean due to imbalance. At sufficient speed, cone effect response to the tilted EUC steers the EUC enough to change its path inwards of the path of the riders center of mass. This corrects for the lean, and still assuming no relative foot movement, as the rider returns to vertical, then so does the EUC. The speed of stability varies with the EUC. My V8F becomes self-stable at around 6 to 8 mph, while an MTen3 become self-stable at around 3 to 4 mph.

 

Edited December 15, 2021 by rcgldr

[.....]

1 hour ago, Tawpie said:

dang cones. I guess though, it's comforting to see that the physics work pretty much as expected. Still, I don't like the "this side of the trench, overcorrect, that side of the trench, overcorrect" underdamped result. Practice practice practice until the muscles handle this by themselves like they do starting an intentional turn. Brain is just too slow.

Thank you @Eucner!

Ruts are the bane of motorcycles and euc's both. You are NOT alone. I've 3 decades+ of riding motos off-road. I may not be all that good at it, but I'm not the only one whos suffered cross-rut incidents and has had to focus REALLY hard while entering a rutted berm turn. We wont even talk about how bad get worse, when a rut is so deep your pedals/pegs become a concern too. I also cant think fast enough, so I usually avoid ruts, or dive right in and hammer down on the throttle. Barely crashing and obviously crashing are the same thing when it comes to ruts. Sometimes it seem that throwing caution to the wind is more likely to end in success, than proceeding timidly.

Edited December 15, 2021 by ShanesPlanet

[Eucner]

7 hours ago, rcgldr said:

Terminology: camber thrust is related to deformation versus lateral loads (applies to bikes, cars, ...). Camber effect is the cone effect. 

Assume no relative foot movement by the rider, so that the EUC is leaned the same as the rider, and a small lean due to imbalance. At sufficient speed, cone effect response to the tilted EUC steers the EUC enough to change its path inwards of the path of the riders center of mass. This corrects for the lean, and still assuming no relative foot movement, as the rider returns to vertical, then so does the EUC. The speed of stability varies with the EUC. My V8F becomes self-stable at around 6 to 8 mph, while an MTen3 become self-stable at around 3 to 4 mph.

Thanks. If you would put a weight on the pedals and let the EUC go without driver, what would happen? To my understanding it wouldn't stay upright very long, like bicycle would do. So it is not self-correcting. It does have effects helping the driver to keep it up, like you described.

[mrelwood]

1 hour ago, Eucner said:

Thanks. If you would put a weight on the pedals and let the EUC go without driver, what would happen? To my understanding it wouldn't stay upright very long, like bicycle would do. So it is not self-correcting. It does have effects helping the driver to keep it up, like you described.

It definitely stays upright very well, if it has reached the required speed, which is not at all high. That’s why some people even consider a leash to be an important addition, to prevent a lone running wheel.

I guess you haven’t watched Hirsute’s videos… or seen my brother practice jumping back onto a lone running wheel… 

[rcgldr]

2 hours ago, Eucner said:

Thanks. If you would put a weight on the pedals and let the EUC go without driver, what would happen? To my understanding it wouldn't stay upright very long, like bicycle would do. So it is not self-correcting. It does have effects helping the driver to keep it up, like you described.

As mrelwood posted, a lone running wheel is stable if going fast enough. Jumping off and then back onto a lone running wheel is called walk the dog.

If weight is going to be added to an EUC, the weight needs to be higher, so that it takes less lateral force for the wheel to steer under the center of mass of the system. Since the trick is called walk the dog, how about an actual dog on an EUC? In this case, the EUC remains stable (it does  turn, but doesn't fall) despite the dogs movements, and when the dog stands up, the EUC becomes mostly vertical and goes straight near the end of the ride. 

https://www.youtube.com/watch?v=MBtSQHT3CCo

 

Edited December 15, 2021 by rcgldr

[Eucner]

16 minutes ago, mrelwood said:

It definitely stays upright very well, if it has reached the required speed, which is not at all high. That’s why some people even consider a leash to be an important addition, to prevent a lone running wheel.

I guess you haven’t watched Hirsute’s videos… or seen my brother practice jumping back onto a lone running wheel… 

I'm a great fan of Hirsute, but not sure if everything he does translates to normal. Here we can see wheel going straight and turning by on it's own. Both shots last only few seconds and might have needed several takes.

 

20 minutes ago, rcgldr said:

If weight is going to be added to an EUC, the weight needs to be higher, so that it takes less lateral force for the wheel to steer under the center of mass of the system. For example, how about a dog sitting on an EUC? In this case, the EUC remains stable (it does  turn, but doesn't fall) despite the dogs movements, and becomes mostly vertical and goes straight near the end of the ride. 

https://www.youtube.com/watch?v=MBtSQHT3CCo

 

It is fun to see dog riding a wheel. At the first it is carving deeply and then it straightens up. I wouldn't rule out dog actively balancing it.