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hackingonempty 2 days ago [-]
> four wheels would double the rolling resistance and thus the effort required to push the cart
Rolling resistance = Crr * N where N = the normal force a.k.a. the weight bearing down on the wheel for a slow moving cart. If you use the same tires but double the axles you reduce the weight on each wheel by half leading to about the same rolling resistance for the vehicle as a whole.
> its narrow wheels minimize rolling resistance
This is a myth that has gripped the bicycle industry for decades but has been slowly dying over the last two. Fat tires have slightly lower rolling resistance at the same pressure and a smoother ride at the same rolling resistance. It takes more energy to lift a hard wheel over a small bump than for a softer wheel to deform and lift less so the difference becomes greater as soon as the road isn't perfectly smooth.
The main reason road racing tires only got a little fatter and aren't as fat as say e-bike tires is aerodynamics which is hardly applicable to hand carts.
> Unlike a van or a car, my handcart doesn’t need gasoline, electricity, or batteries, making it entirely independent from energy infrastructures.
TANSTAAFL - you're going to need more calories to compensate for the additional effort you're expending to move your handcart. Human food is far from the cheapest fuel and few people are able to obtain it "entirely independently from energy infrastructure."
Epa095 2 days ago [-]
"Many people have asked us why we didn’t build a four-wheeled cart that wouldn’t need to be balanced. However, four wheels would double the rolling resistance and thus the effort required to push the cart. Furthermore, a four-wheeled cart is less maneuverable and more difficult to drive on uneven terrain. You also need to get two extra wheels, and you need to build a steering mechanism.
"
I would have asked them why they didn't make a 3 wheeled version. Keep the two big wheels on the side, add a smaller freely rotating one in the front, like a lot of strollers have. They could make it just a tiny bit too low, so it's easy to roll it with both 2 or 3 wheels.
kjs3 2 days ago [-]
I have a 4-wheeled wheelbarrow/cart/whatever. I think Scotts made it, but I could be wrong (it's green with orange lettering); I got it at some big-box years ago. It's wildly easier to move than my regular wheelbarrow, precisely because you expend no effort balancing it, and it's equally easy to use pulling as pushing (even with kinda crappy small, hard wheels). It is definitely not as maneuverable as the traditional, but it's easier on (most, not all) 'uneven terrain' (again, I don't have to balance it) and it doesn't have any 'steering' other than pushing the handles so it points the direction I want to go (I do know there are more elaborate versions that have a steerable set of wheels; I got the cheap version).
I guess tl;dr: I dunno what these guys are going on about and wonder if they've ever actually tried a 4 wheel cart.
SOLAR_FIELDS 2 days ago [-]
As the article points out these things are lovely until you have a hill. Fortunately the original designer built it for use in the Netherlands, a country purpose built for human powered vehicles due to its flatness. I do question its utility in any environment even remotely less flat than NL. I guess you could take it to Denmark too?
readthenotes1 2 days ago [-]
It has always amazed me how even an almost imperceptible upslope can increase effort moving up it.
I guess the answer here is something like a ski lift powered by the handcarts going downhill.
SOLAR_FIELDS 2 days ago [-]
I would pay to see that contraption. I'd pay double to ride the ski lift
s17tnet 2 days ago [-]
Stroller can be seen has specialised handcart.
There is a guy ( Nicolò Guarrera ) who completed a world tour by walk and his tool of choice to transport stuffs was a trekking stroller.
What about a line of wheels in the middle (however many you want, like 3x1 or 4x1) instead of another row of 2x2 wheels, for carrying more weight?
louwrentius 2 days ago [-]
This is the site that runs their blog on solar power, and was an inspiration for me to do the same (now my setup powers my home too). Love the site and all the various concepts about sustainability.
ErroneousBosh 2 days ago [-]
Given that it appears to be made (at least all the mechanical bits) out of bike parts, I kind of wonder why they didn't just make a cargo bike.
If you need to push it, you can push a cargo bike probably easier than this.
If you're really worried about rolling resistance give it suspension.
starkparker 2 days ago [-]
Did you see the section of the article that responds to that exact non-hypothetical question posed to them while using it?
ErroneousBosh 1 days ago [-]
I did see that. It sounds like they just like finding ways to make life hard for themselves.
Rolling resistance = Crr * N where N = the normal force a.k.a. the weight bearing down on the wheel for a slow moving cart. If you use the same tires but double the axles you reduce the weight on each wheel by half leading to about the same rolling resistance for the vehicle as a whole.
> its narrow wheels minimize rolling resistance
This is a myth that has gripped the bicycle industry for decades but has been slowly dying over the last two. Fat tires have slightly lower rolling resistance at the same pressure and a smoother ride at the same rolling resistance. It takes more energy to lift a hard wheel over a small bump than for a softer wheel to deform and lift less so the difference becomes greater as soon as the road isn't perfectly smooth.
The main reason road racing tires only got a little fatter and aren't as fat as say e-bike tires is aerodynamics which is hardly applicable to hand carts.
> Unlike a van or a car, my handcart doesn’t need gasoline, electricity, or batteries, making it entirely independent from energy infrastructures.
TANSTAAFL - you're going to need more calories to compensate for the additional effort you're expending to move your handcart. Human food is far from the cheapest fuel and few people are able to obtain it "entirely independently from energy infrastructure."
I would have asked them why they didn't make a 3 wheeled version. Keep the two big wheels on the side, add a smaller freely rotating one in the front, like a lot of strollers have. They could make it just a tiny bit too low, so it's easy to roll it with both 2 or 3 wheels.
I guess tl;dr: I dunno what these guys are going on about and wonder if they've ever actually tried a 4 wheel cart.
I guess the answer here is something like a ski lift powered by the handcarts going downhill.
There is a guy ( Nicolò Guarrera ) who completed a world tour by walk and his tool of choice to transport stuffs was a trekking stroller.
https://youtu.be/FEgTg_IyHwQ
HN comments at https://news.ycombinator.com/item?id=17792329 and https://news.ycombinator.com/item?id=4285086 .
If you need to push it, you can push a cargo bike probably easier than this.
If you're really worried about rolling resistance give it suspension.