[polishdude20]

Wouldn't a legged vehicle still have that problem if it can achieve the same speeds and weights that regular cars go at?

Scale up a human for example to the weight and speed of a car. Crazy powerful and big legs, big feet, big shoes. The rubber must hit the road either way and push down with a force to propel the weight of this car-heavy legged human at speeds of 100km/h. It would still wear rubber away just like tires do.

Legged vehicles aren't a replacement for regular vehicles if tire particulates are your concern.

[user_7832]

> It would still wear rubber away just like tires do.

It’s been a hot minute since I learnt rolling friction in high school physics but (iirc) a very interesting and unintuitive aspect of it is that there’s always an opposing/slowing force on a (rubber) wheel. Only a slippping wheel will not experience a slowdown. Static friction is different from rolling friction, and (I think) can offer zero wear in ideal conditions - but rolling wear is always non-zero.

[fragmede]

> The rubber must hit the road

if the wheels were metal and the roadway was also metal, but arranged into parallel small roadways, then we could avoid using rubber and not have the problem of rubber particulates.

[anamexis]

Seems like in that case, you could just use cogwheels and racks, and avoid the complexity of legs.

[ada1981]

like, trains?

[anamexis]

Yes, specifically cog railways.

[mensetmanusman]

Metal particles are more reactive and toxic than rubber particles.

[numpad0]

You'll get microsteels, microstones, microbrakedusts and microlubricants for trains, by the way. Some of those may also qualify as microplastics too.

[necovek]

Couldn't you do away with rubber and shoes since for legs you don't need flat, smooth roads either (so metal legs of a multi-ton vehicle won't have anything to damage too bad).

For comfort, you could have springs and air and hydraulic dampeners.

[polishdude20]

The metal itself would damage the ground that is walked on though no?

[necovek]

Yes, but walking on rough terrain would still keep it a rough terrain.

[wizzwizz4]

Rough terrain with less and less purchase, until it just turns into a pile of dry dust / wet mud (depending on weather). A legged vehicle as heavy as a car would wear away stone, tear roots… I don't think there's any surface that could withstand heavy traffic, except maybe something ridiculous like a fast-growing woody grass.

[wizzwizz4]

For some reason, I was imagining a machine with legs like a footstool. Any realistic machine like this would have large, wide feet. With proper suspension, the pressure might be low enough to not completely destroy the ground.

Though, I'm struggling to see how this would be better than a wheeled vehicle: you've still got static friction between the feet and the ground… I guess maybe they're flexing less?

[necovek]

Yeah, large feet would reduce the pressure on the ground, though it would still suffer some effects for sure — but the goal is to avoid rubber and microplastics, so metal feet it is :)

Anyway, I agree that a wheeled vehicle is probably going to win on efficiency just the same, though wheels do require better roads than legs do (eg. common example is stairs).

[lucianbr]

> one big upside is that you can theoretically avoid the rubber/microplastic particulate emission associated with tires and wheeled vehicles if you can make legged vehicles as good as wheeled ones.

How does keeping rough terrain rough help with that?

[necovek]

My implication is that you want rubber for nice asphalt/road surface to avoid damaging it — for comfort, other suspension components can help out instead.

If you don't care about preserving the terrain (which you can when it's rough to begin with), you can just go with large surface metal feet and you should not get any rubber/microplastics, though you will get metallic dust.

[lucianbr]

Wht do you think mountain bikes have rubber tires? Or one of these? https://en.wikipedia.org/wiki/All-terrain_vehicle Or a dune buggy?

Pretty clearly the worry about the road surface is not the only cause of using tires.

Also, if you don't care for either preserving the surface or comfort (use something else for comfort) then... use metal wheels. Or ceramic wheels, or tracks or something.

[Loughla]

I believe the main issue is the rubber and chemicals from the nice road surfaces. So your argument seems like a problem looking for a solution?