Going from a 14in to 18in wheel, suggestions?

[Planemo]

I agree with a lot of what you say. Point 1 isnt under question, thats a given.

Point 2 is the crux - and you bring an interesting perspective - are we reaching the point where large, heavy wheels are wheelspinning under accelereration? I didnt think we were, but I stand to be corrected. If we are not then this brings me onto....

All your comments re moment, length of arm and the amount of lean are correct of course, but could this not just be compensated for in the software. Eg (just throwing some figures out) say an 18" wheel needs 2 deg of lean Vs 1 deg of a 12" wheel. The software could be accomodated to take it into account. As various people have suggested earlier, this may make for a very 'sensitive' pedal or 'firm' ride mode but I dont think this would be beyond a skilled rider. Bearing in mind a big (18"+) hardcore wheel that is very fast (acceleration and top speed) would generally be bought by an experienced rider anyway.

[svenomous]

I think what I'm trying to get at is that even a 0.0001 degree lean must cause a reaction, because it means the chassis is rotating off level.  The wheel must move, even if just infinitesimally, to nudge the system back into balance.  The same goes for a 1 degree or 2 degree lean.  It's physics that decides what the wheel must do to counteract the lean, not manufacturer decisions.  The only thing that motor power/torque can affect is how quickly equilibrium is restored.  A less powerful motor might struggle to correct the leaning angle and ultimately succeed after 200ms, while a stronger motor might do it in just 50ms and be perceived as "more nimble" because the wheel as a system reacted more quickly to the CG-change input.  The amount of improvement that can be achieved by increasing motor torque is strictly limited, though.  So you're right, @Planemo: with enough torque increase, a larger wheel can feel more nimble because it reacts more "zippily" to the rider's leans.  However, to scale up mass and power and expect to be able to maintain the exact same acceleration curve as a smaller wheel is only reasonable up to a point, because past a certain point the wheel will not have enough traction to accomplish it.

[Planemo]

17 minutes ago, svenomous said:

 However, to scale up mass and power and expect to be able to maintain the exact same acceleration curve as a smaller wheel is only reasonable up to a point, because past a certain point the wheel will not have enough traction to accomplish it.

I agree, make the wheel too heavy and eventually no amount of power will make it accelerate because of wheelspin. I just didn't think we were anywhere near that point yet hence my question of adding more power/bigger motors to 18"+ wheels to give the hardcore riders something to chat about. For sure, on smooth asphalt you would need an extremely heavy wheel with an awful lot of power to wheelspin an EUC.

To be honest, I am amazed at how much grip we actually get out of our wheels from a single, small contact patch. I am constantly surprised at how quickly both my wheels can stop on grass for example.

[UniVehje]

26 minutes ago, Planemo said:

To be honest, I am amazed at how much grip we actually get out of our wheels from a single, small contact patch. I am constantly surprised at how quickly both my wheels can stop on grass for example.

This is also just physics. Friction does not depend on the surface area of contact between materials. It’s about load. All our weight is on that small patch. 

[Planemo]

I was already taking the weight of the wheel and rider into account as that's a given. I still find it amazing. Which is why I thought we were still some distance away from wheelspinning EUC's. In any event, I don't think the extra weight of an 18" EUC which is able to accelerate as fast as a 14" should give any great increase in the chance of wheelspin. Especially as the contact patch would be even bigger due to a bigger tyre (both diameter and width). And it would also be taking a heavier load...(admittedly over a larger contact patch so it might even out..)

Edited April 25, 2019 by Planemo

[Circuitmage]

I went from 16S to 18L and had similar concerns. My observations;

1) I immediately got on my 18L without a problem. Probably helped that shell/footing was similar, but prob not much. I mean really, I literally took it out of the box, went outside, and had no problem taking it for a quick spin.
2) My 18L isheavier, less nimble. It felt like the difference between driving a 2 door coupe to going to driving a moving van. Also, when I started going up in speed it was much slower to slow down, requires much more lean. I acutally hit 2 cars in 1 day one morning after a couple months on it. Bad day. Probably also because I am going faster.

3) I'm racking up the miles like crazy. Going faster means going longer. It's about 2x-3x faster in miles collection than my 16S was.

4) Vibration when changing position. I know other people have reported this on the 18L....that is when going over 15 mph and you have to move your upper body (leaning under tree branches usually), there is an unexpected oscillation (left and right) when I lean down. This is usually compensated for by slowing down a bit. Took me a while to get used to it as my 16S did not have that. I think it has to do with the extra weight versus how tight I am holding it. I tend not to grip my shell really tight. Not sure, just something to be aware of as it still happens to me.

5) Better safety gear! I slightly bumped up my safety gear when going to faster unit. Not as much as some people do, but I definitely am trying to be a bit more cautious at these speeds. 

[mrelwood]

8 hours ago, svenomous said:

A less powerful motor might struggle to correct the leaning angle and ultimately succeed after 200ms, while a stronger motor might do it in just 50ms and be perceived as "more nimble" because the wheel as a system reacted more quickly to the CG-change input. 

The first time I tried the V10F, it was on the harderst setting, which was incredibly hard. When I tried to lean forward, the wheel fixed the inbalance immediately, effectively cancelling my lean. It was very hard to get it to accelerate. At a softer setting the wheel lets the rider ”fall” to a leaning position and only then starts to chase the balance. This makes for a much more effortless acceleration.

If the riding mode is too soft, the lean position doesn’t feel stable enough for faster accelerations, so the rider will be more careful. The most effortless accelerations are achieved somewhere in the middle. I’d think that a bit softer mode that hardens exponentially very fast as the wheel tilts would be the best.