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Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

cyclingweekly.com

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Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#41

Post by jhanschoo »

_Microft wrote: post #16

I have trouble making sense of this. What is the mechanism at work here[0]? Is it maybe storing energy that otherwise would be lost (e.g. from shocks, jerks, up and down motion of bike and biker while pedalling?) in the springs to convert it into useful motion, like the Achilles tendon helps humans to walk more efficiently [1]? Being a physicist, the name of the tech ("Weight (Mass) to energy Conversion Technology" […

The video shows elastic potential energy being converted into torque in the wheel as the wheel slides vertically down (due to gravity, without springs). The springs help center the resting state. Yes, it looks to me like it's trying to convert the energy wasted in damping into torque. The effect ought to be more pronounced on bumpy terrain and negligible on smooth ground.

Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#42

Post by dclowd9901 »

jeremysalwen wrote: post #40
dclowd9901 wrote: post #32

Earlier quoted context omitted.

The idea seems to be you have a loaded spring at the top of the wheel as it’s rotating forward. The spring is loaded through some mechanism in the axle, which seems to be some sort of fixed axle that loads the spring through weight. As it rotates, the mechanism which forces the spring closed through downward gravitational force ceases to apply, allowing the fixed axle to unload that spring into the unfixed axle, whic…

There's something fundamentally missing from that explanation, because it doesn't explain where the energy is coming from. You can't load a spring without providing energy, and gravity cannot provide energy in a steady state system.

Then how does it assist for gas springs? The reason it _isnt_ hard to push your trunk lid down is because gravity is helping you do so. If you take that gas spring off the trunk, suddenly you need a lot more force to compress it.

I don’t understand your explanation: you can’t load a spring without energy, gravity + mass loads a spring, but gravity + mass isn’t energy. It is literally potential energy isn’t it?

Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#43

Post by pitaa »

Freak_NL wrote: post #18
fergie wrote: post #7

Would love to hear the opinions of some actual mechanical engineers. Can these springs really passively get you +30% efficiency? What about weight? Cyclists are obsessive about reducing rotating mass, and these wheels seem to be seriously chunky. Is this actually a thing that could work?

I mean, TANSTAAFL, right? Does this store some energy when you slow down to release it when you start up again? That would somewhat flatten the energy expenditure curve, which may be a bit more efficient. It would imply that lifting the wheel after you've stopped releases that amount of energy (it seems to do so).

> It would imply that lifting the wheel after you've stopped releases that amount of energy (it seems to do so).

Notice, however, that the springs are actually missing when they show this in the video! Couple that with the fact that he rotates the wheel by hand to a certain position before setting it down, and its evident that the rotation we see is just due to a very imbalanced wheel.

Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#44

Post by KaiserPro »

fergie wrote: post #7

Would love to hear the opinions of some actual mechanical engineers. Can these springs really passively get you +30% efficiency? What about weight? Cyclists are obsessive about reducing rotating mass, and these wheels seem to be seriously chunky. Is this actually a thing that could work?

The springs are compressed as the wheel rolls forward. this means added rolling resistance

Those springs are then decompressed either into another spring inside the drum, or back into the wheel again.

if its option 1 where the springs we can see are decompressed into a central energy store, it might have some application for allow easy starting (ie you press a button and the wheel lets out all its stored energy and spins. taking you from 0-10mph)

If its option 2, then you are just making heat. the springs are compressing at the expense of forward momentum. when you roll forward not only do you have to overcome friction, but also compress a spring at the same time.

If you have another spring on the other side decompressing at the same time, then you get _some_ energy back, minus heat, losses in compressing the spring in the first place, and any other mechanical losses.

In short, its a recipe for a boat load of extra friction/rolling resistance. Which will slow you down.

Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#45

Post by wiredfool »

franciscop wrote: post #26

This article has all the makings of a perpetual motion machine. Those are normally found by using either "springs", "magnets" or a combination of both. There is theoretically a way to use the roughness of the terrain (so the bike going up and down as it rides) to store that energy and then use that for propulsion. When finding a rough spot, the bike trades forward momentum for a vertical impulse, so it might be possi…

There is some research into how much energy is lost to suspension style losses, and it's on the order of 100W (was 300) when riding at 20mph/30kph over rumble strips. (https://www.renehersecycles.com/myth-17-bigger-wheels-roll-f...). This can be changed pretty dramatically with good tires and proper inflation.

On more reasonable road surfaces, it's less than 1/10th of that number. (but good tires make ooooh so much of a difference. I don't notice bad chipseal. My clubmates -- not so much)

(edit sorry -- rereading the article, I misread the graph. 300W on the rumble strips ~200 on the smooth pavement beside them)

Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#46

Post by wiredfool »

orwin wrote: post #24
fergie wrote: post #7

Would love to hear the opinions of some actual mechanical engineers. Can these springs really passively get you +30% efficiency? What about weight? Cyclists are obsessive about reducing rotating mass, and these wheels seem to be seriously chunky. Is this actually a thing that could work?

if this is seen in bike competition, its legit. If it is forbidden, nothing can be deduced about it and if this is allowed but not used, this is useless.

There's a lot of stuff in competition that's not legit.

Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#47

Post by dclowd9901 »

lokedhs wrote: post #13

So if I understand this correctly, it uses the downwards force on the wheel when pushing down on the pedals and converts that into rotational force on the wheel. Now, because of that annoying thing called conservation of energy, this means that you'll have to put this energy into the system by pushing down harder. I guess this translates to a feeling of sitting on a spring. That doesn't sound like very efficient peda…

No. Not when pushing down on the pedals. Your natural weight would be all that would be needed to load the spring. At least that’s my understanding.

Re: Spring-powered wheel claims to be ‘E-bike alternative at lower cost’

#48

Post by lokedhs »

dclowd9901 wrote: post #47
lokedhs wrote: post #13

So if I understand this correctly, it uses the downwards force on the wheel when pushing down on the pedals and converts that into rotational force on the wheel. Now, because of that annoying thing called conservation of energy, this means that you'll have to put this energy into the system by pushing down harder. I guess this translates to a feeling of sitting on a spring. That doesn't sound like very efficient peda…

No. Not when pushing down on the pedals. Your natural weight would be all that would be needed to load the spring. At least that’s my understanding.

Sure, but when would the spring unload? You need to lift your body up do be able to load it again.
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