Tire width - Is wider better?

[Asphalt]

Fortnine made an interesting video putting a car tire on a motorbike. They go over the physics of wide vs narrow tires. While this is an extreme example, it should shed some light on tire width discussions.

There's been a recent trend by EUC manufacturers towards wider 3-inch tires. Most notably with the 3-inch on the KS-16X vs the 2.5-inch on the KS-18XL. This video does a good job explaining the cause of the "gyro effect" felt on the wider tire.

My takeaways from this video are:

1. Wider tires can handle more load, so are better for heavier riders.
2. Wider tires are more stable in a straight line.
3. Wider tires have more flotation on soft terrain, so shouldn't sink as much.
4. Wider tires are more stable when braking.
5. Wider tires track more to the road surface, following depressions in the road, less responsive to rider input.
6. The wider the tire, the greater the gyro effect when turning, requiring "counter-steering" (or whatever the equivalent is on EUCs) throughout a turn.
7. Wider tires will grip less in a turn because some for the grip force goes towards countering the tire wanting to stay flat.
8. Friction force is independent of contact patch size. It is only dependent on the coefficient of friction and the normal force.
9. Wider tires should last longer due to heat distribution and having more material.

Overall, wider tires will run cooler, last longer, but handle poorer.

I like that EUC manufacturers currently offer a wide range of tire widths. I just hope that the trend isn't only towards wider tires.

 

[mrelwood]

Interesting topic, and I will watch the video later on.

But a crucial thing to note is that they didn’t change just the width. They drastically changed the profile of the tire. Your takeaway would be exactly the same even if they hadn’t changed the width at all, but only the profile. A MC tire is round, a car tire is flat. Even the 4.1” tire on the Z10 is round, and doesn’t have even a hint of flattening at the centre. Most tires are actually the opposite of flat, as they have a solid, sometimes even raised centerline, and less and less material towards the edge of the tire.

[tenofnine]

It seems like Kingsong and Gotway are on the right track, a 3 inch wide rounded soft tire is ideal in my opinion.

The rim of the hub motor should probably stay at 16 inches or less (for optimal torque) and the only real improvement would be just to put fatter (balloon type) tires on said rim. More air means more cushion at minimal weight increase. I think a good total rim + tire diameter is 18 inches and 3 inches wide.

Edited February 2, 2020 by tenofnine

[Eko]

Totally agree. 

3 hours ago, mrelwood said:

Interesting topic, and I will watch the video later on.

But a crucial thing to note is that they didn’t change just the width. They drastically changed the profile of the tire. Your takeaway would be exactly the same even if they hadn’t changed the width at all, but only the profile. A MC tire is round, a car tire is flat. Even the 4.1” tire on the Z10 is round, and doesn’t have even a hint of flattening at the centre. Most tires are actually the opposite of flat, as they have a solid, sometimes even raised centerline, and less and less material towards the edge of the tire.

Interesting remark, but "Exactly the same" ?  No,  I don't think so, there are physical implications about different tyres' widths, objective implications, that change riding experience at the same riders' conditions.

[Biped Phil]

7 hours ago, tenofnine said:

... More air means more cushion at minimal weight increase. I think a good total rim + tire diameter is 18 inches and 3 inches wide.

Would helium help keep the weight down?

[Rywokast]

personally i hate anything above 2.5" width.. not nimble enough, hate any gyro effect whatsoever.. could be my weight but the 18XL is perfect, every 3" tire ive tried i hated, the worst being the mten since its almost flat

[D3m0nzz]

45 minutes ago, Rywokast said:

personally i hate anything above 2.5" width.. not nimble enough, hate any gyro effect whatsoever.. could be my weight but the 18XL is perfect, every 3" tire ive tried i hated, the worst being the mten since its almost flat

I am 100% with you on this, but it seems we are the silent minority on the issue  

[alcatraz]

In the cycling community we discuss this subject a lot.

Something worth noting is that the same tire behaves differently on different rims.

The air volume helps to keep a tire from bottoming out. Smaller air volume results in less dampening because of the higher pressure you need to ride.

Different riders prefer different tires depending on their desired comfort, weight, road surface quality.

More choices help everyone to find what they want.

[Rywokast]

3 hours ago, alcatraz said:

In the cycling community we discuss this subject a lot.

Something worth noting is that the same tire behaves differently on different rims.

The air volume helps to keep a tire from bottoming out. Smaller air volume results in less dampening because of the higher pressure you need to ride.

Different riders prefer different tires depending on their desired comfort, weight, road surface quality.

More choices help everyone to find what they want.

i like a thin tire that is rock hard so i can turn on a dime.. plus bouncing over every little bump adds to the fun

[mrelwood]

 

11 hours ago, Eko said:

Interesting remark, but "Exactly the same" ?  No,  I don't think so, there are physical implications about different tyres' widths, objective implications, that change riding experience at the same riders' conditions.

Of course there are, that’s not what I meant. More on this later in bold.

The subject of the video was not what I expected based on the first post of this topic. The whole and sole point was wether or not it makes sense to use a car tire in a motorcycle, like some people used to 50 some years ago. Nothing yet about tire width.

The video is great, a nice watch and filled with good physics and data. It goes through the differences of a car tire and a motorcycle tire in detail, and why a car tire doesn’t fit as well on a motorcycle rim. While the size of the contact patch was also brought in, still nothing about tire width.

In the end they explain why the car tire was so bad on a motorcycle: A car tire is designed to be tilted a maximum of 4 degrees, while a motorcycle tire is designed to work well even under an extreme tilt. Still nothing about tire width.

What @Asphalt got from the video, he labeled as ”a wide tire vs a narrow tire”. But the width wasn’t even a factor in the video. It was all about a square tire vs a round tire. Even if the car tire in the video had been exactly the same width than the motorcycle tire, it wouldn’t have changed any of the points or outcome of the video. It would still be a square tire, and it would still behave like a square tire.

 

So if you like a wide tire on an EUC, don’t be alarmed! It’s still as great of an improvement than it ever was. Just read the original post by reading every ”wide” word as ”square”. 

[Ddolik]

Great. Thanks for the awesome read.

[Chriull]

17 hours ago, Asphalt said:

Fortnine made an interesting video putting a car tire on a motorbike. They go over the physics of wide vs narrow tires. While this is an extreme example, it should shed some light on tire width discussions.

There's been a recent trend by EUC manufacturers towards wider 3-inch tires. Most notably with the 3-inch on the KS-16X vs the 2.5-inch on the KS-18XL. This video does a good job explaining the cause of the "gyro effect" felt on the wider tire.

As @mrelwood already wrote the videos topic is square vs round tire!

The cornering behaviour is determined by the wheels profile.

A nice link describing cornering is https://motochassis.com/Articles/Tyres/TYRES.htm

So there are two ways to corner a tire:

-Generate slip by steering the tire "more to the center of an corner as necessary" so a slip is generated. As done with cars and their square tires. Could maybe also be achieved with EUCs but should belong to very advanced riding techniques/special tricks&stunts.

With such square tires on an EUC one would drive more like with a double wheeler (airwheel q3)

- use the reduced tire circumference of a leaned round tire (?camber trust?). So we get exactly one specific turning radius at a specific speed with a specific lean angle. This lean angle is determined by the tire profile(cross section roundness).

So one could construct a 3 inch tire with enough "shoulder height" with an extreme eliptical profile which would be much more "nimble for cornering" than all the 2 inch tires used by now. (With the same max outer diameter)

But as space for the shoulder height is limited (and higher tire shoulders tend to get more "unstable") normally wider tires have a less round profile as thinner tires. And exactly this profile difference make them harder to turn/more stable to go straight.

By this also the user air pressure has (can have) an influence on the turning characteristics - by the deformation with less air pressure the profile "becomes more square" and with more air pressure it stays "rounder"

[LanghamP]

5 hours ago, mrelwood said:

In the end they explain why the car tire was so bad on a motorcycle: A car tire is designed to be tilted a maximum of 4 degrees, while a motorcycle tire is designed to work well even under an extreme tilt. Still nothing about tire width.

The video mentioned a specified government (?) safety standard, whereby if something failed there was a backup.

--The sidewall is kept on by both air pressure and a tire to edge of wheel lip.

--The tire is kept on by both air pressure and a tire to internal wheel lip.

So neither the tire sidewall nor the tire itself can easily come off the wheel.

Because the two lip to tire contacts align when using a car tire on a bike rim, that means there is no safety redundancy should your bike tire go flat (in my opinion an almost statistical certainty...a few weeks ago a pulled yet another screw from my car tire).

I would not use a car tire for that single factor. You'd lose air before you'd even notice, and nails are so common that patching tires has become a semi normal process for me (I don't use slime because it's difficult to clean up when changing tires).

Edited February 3, 2020 by LanghamP

[Eko]

6 hours ago, mrelwood said:

 

Of course there are, that’s not what I meant. More on this later in bold.

The subject of the video was not what I expected based on the first post of this topic. The whole and sole point was wether or not it makes sense to use a car tire in a motorcycle, like some people used to 50 some years ago. Nothing yet about tire width.

The video is great, a nice watch and filled with good physics and data. It goes through the differences of a car tire and a motorcycle tire in detail, and why a car tire doesn’t fit as well on a motorcycle rim. While the size of the contact patch was also brought in, still nothing about tire width.

In the end they explain why the car tire was so bad on a motorcycle: A car tire is designed to be tilted a maximum of 4 degrees, while a motorcycle tire is designed to work well even under an extreme tilt. Still nothing about tire width.

What @Asphalt got from the video, he labeled as ”a wide tire vs a narrow tire”. But the width wasn’t even a factor in the video. It was all about a square tire vs a round tire. Even if the car tire in the video had been exactly the same width than the motorcycle tire, it wouldn’t have changed any of the points or outcome of the video. It would still be a square tire, and it would still behave like a square tire.

 

So if you like a wide tire on an EUC, don’t be alarmed! It’s still as great of an improvement than it ever was. Just read the original post by reading every ”wide” word as ”square”. 

Hi, mrelwood.  Thanks for your detailed explanation.  I'll honestly admit I didn't see the video, no time available last night.  Now it's all clarified. The title's not corresponding to video's content

Only a "doubtful" question:  is there even a single unique car tire of the same width than a single unique motorcycle tire ?    Did they actually find that (for real test and trials)? 

[AtlasP]

On 2/2/2020 at 7:41 PM, D3m0nzz said:

On 2/2/2020 at 6:55 PM, Rywokast said:

personally i hate anything above 2.5" width.. not nimble enough, hate any gyro effect whatsoever.. could be my weight but the 18XL is perfect, every 3" tire ive tried i hated, the worst being the mten since its almost flat

I am 100% with you on this, but it seems we are the silent minority on the issue  

Count me in as well, although I don't think we're a minority so much as marginalized. #2.5intirebesttire ;-)

It calls into question how much the community's discourse is swayed by a few of the most prominent public figures and their unique situation/opinion. For example Marty seems like the nicest guy with a ton of experience, but his context of often riding on public mountain trails overlooking LA is incredibly niche. He rides a lot off road, up and down literal mountains, and going for distance (recommending only 1600Wh wheels for his group rides, 40/50+ miles at a time). I'd bet the majority of riders (like way more than half) are only riding on streets and essentially never off-road (certainly not as a regular occurrence), are never going to ride on a hill anywhere close to "overheat hill" and certainly not for so many minutes straight (outside of SF and relatively few other similar locations), and are likely much more concerned with nimbleness weaving around bicycles/potholes/obstacles in dense urban environments and overall wheel weight for use as a daily commuter than cushiness in a straight line and 50+ mile range. Then he goes and says that all wheels should be at least 3" wide--which makes total sense if you're going to do a lot of off-roading for hours in pretty straight lines up mountains, but not necessarily for the majority of riders.

Of course Marty contributes a great deal to the community by putting wheels through their paces and offering his insight _for his unique usage case_. But it is extremely likely that the vast majority of riders do not share that usage case, and thus his conclusions/opinions/preferences don't all necessarily translate to your average urban rider/commuter and their situation. Or certainly some of his conclusions/opinions/preferences still do, but some don't, and he doesn't always make that distinction explicit nor do a lot of average riders who might watch such videos think about that distinction ("which parts of this do or don't apply to my riding context").

This isn't to single Marty out, it's just an example. The same could be said for the portion of the NYC crew who like to post videos tearing through Manhattan weaving in and out of cars, who value top speed over all else (and will forgive pretty much any and every other failing of a wheel as long as it goes the fastest). And similarly for their usage (dodging traffic) of course it makes sense whey they would value speed over all else. Although again this is an extremely prominent and vocal but ultimately minuscule minority perspective.

The problem is normal and conscientious riding in ordinary locations (i.e. not a gorgeous mountaintop overlooking LA or through the center of bustling Manhattan) makes for incredibly boring youtube videos. ;-)

Edited February 7, 2020 by AtlasP

[Asphalt]

@mrelwood Glad you watched the video before posting your opinion.

Apart from #7, which I agree has more to do with tire profile than width, do you disagree with any of the other takeaways?

Quote

1. Wider tires can handle more load, so are better for heavier riders.
2. Wider tires are more stable in a straight line.
3. Wider tires have more flotation on soft terrain, so shouldn't sink as much.
4. Wider tires are more stable when braking.
5. Wider tires track more to the road surface, following depressions in the road, less responsive to rider input.
6. The wider the tire, the greater the gyro effect when turning, requiring "counter-steering" (or whatever the equivalent is on EUCs) throughout a turn.
7. Wider tires will grip less in a turn because some for the grip force goes towards countering the tire wanting to stay flat.
8. Friction force is independent of contact patch size. It is only dependent on the coefficient of friction and the normal force.
9. Wider tires should last longer due to heat distribution and having more material.

 

[Nic]

3 minutes ago, Asphalt said:

Apart from #7, which I agree has more to do with tire profile than width, do you disagree with any of the other takeaways?

8. Friction force is independent of contact patch size. It is only dependent on the coefficient of friction and the normal force.

https://suspensionsecrets.co.uk/tyre-performance-and-grip-a-deeper-look/

1. Adhesion Grip (#8 in your list)
2. Hysteresis Grip
3. Interaction With The Road Surface

[Rywokast]

4 hours ago, AtlasP said:

Count me in as well, although I don't think we're a minority so much as marginalized. #2.5intirebesttire ;-)

It calls into question how much the community's discourse is swayed by a few of the most prominent public figures and their unique situation/opinion. For example Marty seems like the nicest guy with a ton of experience, but his common riding context on public mountain trails overlooking LA is incredibly niche. He rides a lot off road, up and down literal mountains, and going for distance (recommending only 1600Wh wheels for his group rides, 40/50+ miles at a time). I'd bet the majority of riders (like way more than half) are only riding on streets and essentially never off-road (certainly not as a regular occurrence), are never going to ride on a hill anywhere close to "overheat hill" and certainly not for so many minutes straight (outside of popularity in SF and relatively few other similar locations), and are likely much more concerned with nimbleness weaving around bicycles/potholes/obstacles in dense urban environments and overall wheel weight for use as a daily commuter than cushiness in a straight line and 50+ mile range. Then he goes and says that all wheels should be at least 3" wide--which makes total sense if you're going to do a lot of off-roading for hours in pretty straight lines up mountains.

Of course Marty contributes a great deal to the community by putting wheels through their paces and offering his insight _for his unique usage case_. But it is extremely likely that the vast majority of riders do not share that usage case, and thus his conclusions/opinions/preferences don't all necessarily translate to your average urban rider/commuter and their situation. Or certainly some of his conclusions/opinions/preferences still do, but some don't, and he doesn't always make that distinction explicit nor do a lot of average riders who might watch such videos think about that distinction ("which parts of this do or don't apply to my riding context").

This isn't to single Marty out, it's just an example. The same could be said for the portion of the NYC crew who like to post videos tearing through Manhattan weaving in and out of cars, who value top speed over all else (and will forgive pretty much any and every failing as long as their wheel goes the fastest). And similarly for their usage (dodging traffic) of course it makes sense whey they would value speed over all else. Although again this is an extremely prominent and vocal but ultimately minuscule minority perspective.

The problem is normal and conscientious riding in ordinary locations (i.e. not a gorgeous mountaintop overlooking LA or through the center of Manahattan) makes for incredibly boring youtube videos. ;-)

exactly.. although i do love going for long rides, 95% of my riding is in a densely populated city, bike lanes, buses, people, bad drivers/tourists.. i wish i had hours and hours of beautiful mountain trails near me lol.. and the 5% of my riding that is not within the city is on paved bike trails.. i NEVER offroad, ever... i dont even know of a single place to offroad where im from lol

Edited February 4, 2020 by Rywokast

[mrelwood]

 

5 hours ago, Eko said:

Only a "doubtful" question:  is there even a single unique car tire of the same width than a single unique motorcycle tire ?    Did they actually find that (for real test and trials)? 

The tire widths weren’t mentioned, but my guess for the car tire would be the common 205mm. The Hayabusa sports a 190mm tire, and the BMW GS in the video comes with a 170mm tire. 

 

1 hour ago, AtlasP said:

"which parts of this do or don't apply to my riding context"

I think you are on point. But this is a much wider issue than EUCs. Every person needs to be able to judge every single piece of information they get from anywhere, wether the source of information is valid and relevant. Unfortunately actively doubting everything would require too much work, so we let a lot of stuff slip in easy. Advertisers surely know a whole lot about this, and they try their best to fool people into thinking that a piece of information in an ad would actually be a fact. (Boy could I ramble on about this!)

Anyway, I don’t think it’s up for the vlogger to make the distinction. If it would, they’d have to disclaimer every word they say.

I’d even go far enough to suggest that your idea of a common rider profile might also be skewed just as much as mine surely is. 

 

1 hour ago, Asphalt said:

Apart from #7, which I agree has more to do with tire profile than width, do you disagree with any of the other takeaways?

First of all, I disagree with any of them being a takeaway from a video that doesn’t discuss or even mention the word ”width”! As separate points, I disagree with #4, #5, #7 and #9.

[tenofnine]

Yea it's a very interesting video, and I honestly didn't know there was a term for this (I've seen it before though)

And this is a worthwhile topic (tire width and preferences, etc) but a motorcycle is so so so much different than an electric unicycle. A motorcycle is essentially an inverse pendulum and is subject to some very weird counter-intuitive physics similar to what trying to balance an upside-down broom on your hand feels like. If you've ridden a road bike or mountain bike at high speeds you will know what the phenomenons like counter-steering feel like and how influential rear and front tires can be on these forces.

With an EUC we only have to worry about overcoming the gyroscopic force of the tire and rim, and the tire shape and size have a pretty proportional and intuitive effect on handling (unlike motorcycles).

Edited February 3, 2020 by tenofnine

[Asphalt]

3 hours ago, Nic said:

https://suspensionsecrets.co.uk/tyre-performance-and-grip-a-deeper-look/

1. Adhesion Grip (#8 in your list)
2. Hysteresis Grip
3. Interaction With The Road Surface

Thank-you for this informative link. This is the first time I’ve heard of hysteresis grip.

Do I understand hysteresis grip correctly? - As the rubber compound loads and unloads, some of the energy becomes heat which softens the rubber, improving adhesion grip.
For interaction with the road, undulations in the road surface cause loading and unloading on the tire surface which begins the hysteresis process.

Am I interpreting the article incorrectly or are both hysteresis and interaction with road surface both sources of additional adhesion grip? I’m not trying to be argumentative - my interpretation may be off...again 

I appreciate everyone’s time in contributing knowledge to this discussion. Hopefully this will eventually lead to more informed decisions about what we want out of an EUC.

[Dzlchef]

I will add that I've now worn down 2 of my tires on the Nikola, 3" tire, and I love the feel of the nearly bald tire. All of the gyro effect is gone and it's smooth and effortless carving. I'm wondering how long I can ride on the bald tire before I need to change again? Getting used to the brand new tire takes some time and patience. Last time I nearly lost it a few times carving to hard. 

[mrelwood]

 

3 hours ago, tenofnine said:

A motorcycle is essentially an inverse pendulum

I think you meant EUC... 

3 hours ago, tenofnine said:

With an EUC we only have to worry about overcoming the gyroscopic force of the tire and rim, and the tire shape and size have a pretty proportional and intuitive effect on handling (unlike motorcycles).

I think someone wiser calculated that the actual gyroscopic forces are a bit too small at the speeds we ride, so that the ”gyroscopic effect” we feel is actually mostly just a behaviour of the tire profile. And since the actual gyroscopic force would be the same for every tire shape, thread, and wear level, what we feel with wide tires indeed must be something else.

 

2 hours ago, Asphalt said:

Do I understand hysteresis grip correctly?

I’m familiar with the word from a completely different topic (audio DSP), and while not at all sure, I would think hysteresis to mean the difference between when the tire starts to slip and when it regains grip. Like speed wobbles can have hysteresis, so that if the wobbles start at 40km/h, they only stop if you get down to 35km/h. That 5km/h (or -5, not sure) would be called hysteresis.

 

2 hours ago, Dzlchef said:

I will add that I've now worn down 2 of my tires on the Nikola, 3" tire, and I love the feel of the nearly bald tire.

If I were you, I’d consider trying a different tire. Two down already is a very fast wear! For me 5000km is common from a single tire.

ChaoYang H-666 should be available as a 16x3.0, and at least as a 18x3.0 it’s the most beautifully handling tire I’ve ridden on. Carves just right, and lets me go much faster in tight corners than any other tire.

[tenofnine]

2 hours ago, mrelwood said:

 

I think you meant EUC... 

I think someone wiser calculated that the actual gyroscopic forces are a bit too small at the speeds we ride, so that the ”gyroscopic effect” we feel is actually mostly just a behaviour of the tire profile. And since the actual gyroscopic force would be the same for every tire shape, thread, and wear level, what we feel with wide tires indeed must be something else.

 

Nope i definitely meant motorcycle, an EUC is almost comparable to a regular pendulum since it's the weight is near the ground and your body is like the arm. Physicist relate a motorcycle/bike to an inverse pendulum since the lion share of the weight is high off the ground near the body making it a top heavy system that is prone to inverted forces at higher speeds (like the upside down broom example I gave, to balance you have to compensate in the opposite direction to keep it upright). The 2 wheel design is also a large factor in that comparison as well since it allows for self correcting steering and stability at speed (hand's free riding, etc....as long as it's balanced right) and interactions like counter-steering.

 

With an EUC a small dense weight is at our feet close to the ground and we are much heavier than that object. It roughly resembles an actual regular pendulum, but you can't really compare the two. I would argue that gyroscopic forces definitely are a very real thing and it becomes more obvious in designs like the Z10 where a large portion of the weight is the wheel (hub motor, rims and tire). It's why you see videos where the rider falls off and the EUC stays upright, corrects itself, and rides on by itself (also how that dog can ride on top of that kingsong EUC). And it's why when I make turns at highers speeds I have to actively push my body-weight against one side so much I actually have to shift my CoG so far to one side it looks like I should fall off (if you took a photo mid-turn)

[mrelwood]

16 minutes ago, tenofnine said:

Nope i definitely meant motorcycle, an EUC is almost comparable to a regular pendulum since it's the weight is near the ground and your body is like the arm. Physicist relate a motorcycle/bike to an inverse pendulum since the lion share of the weight is high off the ground near the body making it a top heavy system that is prone to inverted forces at higher speeds (like the upside down broom example I gave, to balance you have to compensate in the opposite direction to keep it upright). The 2 wheel design is also a large factor in that comparison as well since it allows for self correcting steering and stability at speed (hand's free riding, etc....as long as it's balanced right) and interactions like counter-steering.

I might have profoundly misunderstood your post, but in case I didn't, your view is quite different from mine and also from the guys at the forum with much more physics education than me.

1. The EUC's fundamental and clearly the most important job is to balance the broom (the rider) on it's hand (the pedals). Front to back it propels the motor, left to right not much as it is limited by the tire's self-correcting abilities. No vehicle gets more inverse pendulum than that. The term "inverted pendulum" gets 52 results in this forum, dating back up to five years. 
2. The only axis a motorcycle can be though of being an inverted pendulum on is left to right. I fail to see how the EUC differs in that regard, it still has a contact point at the bottom, a self-steering tubular tire, and an unbalanced weight on top that the system is supposed to keep onboard. And front to back the EUC really is a perfect example of a broomstick-on-top-of-the-hand.
3. As you wrote later in your reply, "rider falls off and the EUC stays upright, corrects itself, and rides on by itself". Aren't those the very definition of self-correcting steering?
4. Self-correcting steering, or stability at speed doesn't require two wheels. One of the most common points of a EUC tire discussion is the gyro-like effect, ie the wheel is more stable at speed than what the rider would even prefer.
5. The steering process when riding a motorcycle or a bicycle without hands is very close to an EUC, especially at speed. The frontmost tire is turned to the side both by gyroscopic precession and the smaller diameter at the edge of the tire causing the trajectory to curve.

 

16 minutes ago, tenofnine said:

I would argue that gyroscopic forces definitely are a very real thing and it becomes more obvious in designs like the Z10 where a large portion of the weight is the wheel (hub motor, rims and tire).

To quote from just a few posts above:

5 hours ago, Dzlchef said:

I love the feel of the nearly bald tire. All of the gyro effect is gone

I hope you're not going to argue that the mass of the system has decreased enough by the lost rubber for the gyroscopic forces to disappear...

(Sorry guys, I entered The Rambling Mode. You may want to jump to the last paragraph, marked with: " (*) " ).

I wanted to check how the Gyroscopic force is defined and calculated. Surprisingly, while every force and vector I can think of has a dedicated Wikipedia page, "Gyroscopic force" or "Gyroscopic effect" does not. Then the first line at the page "Gyroscope" hit me:

Quote

A gyroscope is a device used for measuring or maintaining orientation and angular velocity.

It is a device, not a force or a force-like effect.

Anyway, I was trying to get to the point where the only factors that can construct the "force formerly called as gyroscopic force" are mass and speed. The MSX and the 18XL have a noticeably different amount of tendency to stay upright at any speed, yet the weight difference of a [18x2.5" tire and the rim and the hub motor] vs a [18x3" tire and the rim and the hub motor] is way too miniscule to account for anything meaningful. Besides, "the effect" is profoundly different between tires of the same size and weight as well if the profile of the tire is different.

The heaviest EUC tire I've ever ridden is the huge, thick, knobby motorcycle tire CST C-186 that barely even fits the MSX. It has much less tendency to stay upright than any regular 18" EUC tire of any width. And taking the Z10 as an example, I'm sure the rotational mass is much higher than on any other wheel, but so is the tire width and profile.

I can't argue that the rotating mass wouldn't have any effect. Letting the MSX speed up on your hand makes it very difficult to turn. But tire choice has nothing to do with that effect, yet it can change the riding behaviour drastically, and counteract any ill-behaving rotational forces enough not to be an issue.

(Let's keep calling it the gyro-like effect though, "conservation of angular momentum" doesn't really roll off from the tongue.)

 

16 minutes ago, tenofnine said:

I actually have to shift my CoG so far to one side it looks like I should fall off (if you took a photo mid-turn)

(*) Like motorcycle racers, I know. And if your turn radius didn't match, you would fall. This has nothing to do with an actual gyroscope. The most crucial thing to note is that a gyroscope (or conservation of angular momentum) has zero tendency or ability to bounce back. Meaning, if you get it to turn, it has no force trying to get back to where it started from. This is fundamentally different from turning with an EUC. Especially the wheels that have the most gyro-like effect continuously try to get back into vertical position, and that is the force you are fighting. An actual gyroscope would be a b!+c# to get tilting, but once it tilts, it would be the exact same b!+c# to get back in the vertical position. Conservation of momentum tries to conserve the current momentum, not a past one.