momus3 said:
Adding weight is not an issue with this sort of powered vehicle.
Speaking from the experiences of my heavy cargo trikes, it *is* an issue for a number of things, though some may not become apparent at the lower end of the scale.
The frame has to be stronger (and usually that means it itself must be heavier).
The wheels have to be higher pressure (or significantly taller) to resist squishing down and getting pinch flats or damaging rims / breaking wheels (or axles!).
Accelerating (or going up any slope) takes a lot more energy, so it means a much lower gearing and lower speed to use the same energy to go up a slope, or a lot more power to go the same speed, or accelerate at the same rate. More wasted heat, etc. If the motor fails, and you don't have low enough gearing for your strength, you then can't go up the slope or get started moving from a stop (or accleration will be much slower).
Braking becomes more difficult, as there is much more energy to dissipate. So braking distances become longer, even if you have good brakes (because a brake can only do so until the wheel skids, at which point you're no longer braking, you're skidding and have lost control, if your front wheel is skidding, you can't really steer).
Where the added weight goes is important, and conflicting for different purposes.
To keep the wheels loaded evenly, it needs to be in the center, proportionally between all the wheels (hence SB Cruiser's cargo/seatbox with battery/tools/etc in it, and me on it, as close to the middle as I could get it...but when carrying cargo it goes behind that over the rear wheels, so loading is almost all on the rear wheels)
But to decrease tipping, the weight should be divided between the outboard wheels and placed as far outboard as possible (hence SB Cruiser's heavy hubmotor rear wheels, which make it much less prone to tipping than a front hubmotor and regular rear wheels).
Etc.
I still think the solution to trike tipover is plain old physics.
Of course it is.
But it isn't always a simple single solution. Physics is complex, and the more complex the system and the more complex the problem to solve, the more complex the solution may be, as it has more than one thing it has to do.
The problem of trike tipping is not simply the tipping, as noted here and elsewhere. The trike has many things it must do, and may have more depending on your particular uses for one.
The more mass an object has, the more it resists changes to it's direction, and more mass means more inertia at speed, so it will tend to remain on it's trajectory. Gyroscopic action stabilizes objects, keeps them on-center, and a low center of mass increases stability. Leaving aside the horizontal gyro idea, wheels are simple vertical gyros. If I bring the seat way down on a trike, add mass to the lowest possible part of the bike, add more mass to the three wheels with oversize tires, heavy duty thorn proof tubes, slime, and also add a heavy, gyro front hub motor, the tendency to tip over should be substantially reduced.
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This is why motorcycles are much more stable at speed than eBikes. They're much heavier, the weight is generally low, and the bigger and heavier wheels act like gyroscopes. Anyone who has ever ridden a scooter with little wheels immediately notices how much less stable they are than a motorcycle.
It's not the wheel size (or gyroscopic mass), it's overall geometry, proportions of mass above/below axles, etc., and all the other things you're talking about.
Gyroscopic action might make it go in a straight line better, but the stronger it is, the more it makes it harder to turn when you need to, which can make it more dangerous in traffic or some other conditions. If it's not so strong as to keep you from turning easily, it isn't likely to keep it from tipping over in the turn once you get started turning, though.