3 ms·

Would love to hear the opinions of some actual mechanical engineers. Can these springs really passively get you +30% efficiency? What about weight? Cyclists ar

by fergie 6y ago

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?

nxpnsv 6y ago
Yeah, not many cyclists would add 10kg to their bike, typically resulting in doubling the bike weight.
Freak_NL 6y ago
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).
- pitaa 6y ago
  > 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.
orwin 6y ago
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.
- wiredfool 6y ago
  There's a lot of stuff in competition that's not legit.
wiredfool 6y ago
No. There’s no 30% gain to be had. Losses in a properly maintained bicycle are already far lower than this.
- londons_explore 6y ago
  > Losses in a properly maintained bicycle are already far lower than this. Plainly not true. If I cycle a 1 mile lap and come to a stop, I have put in lots of energy yet am in exactly the same position I started in. Bicycling (and most forms of transport) are 100% losses when considered in an "energy in Vs energy out" way.
KaiserPro 6y ago
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.
- dclowd9901 6y ago
  Let’s say you have two boards end to end, each on fulcrums, angled up like an A. Leading to the apex of the two boards, you have a platform at about the height of the apex. Now let’s say you to take a step forward off that platform onto the apex of those two boards at the same time, pushing them down and lifting their ends. Do you have to expend any additional _forward momentum_ energy to take that step? Now let’s say there was a big spring between the opposite ends of those two boards, and that spring just happened to compress at a weight a bit lower than force generated by you stepping onto the apex. Now, imagine stepping off the apex. As you do, you feel the apex rise and push your leg off. Now apply that mechanic around an axle, and use mechanics to ensure only the springs nearing the top of the axle (as it rotates) compress when downward force is applied to the axle itself. That’s as good as I can describe how I understand it, and I can’t see how it violates any physical laws. It’s just a clever use of springs.

by fergie 6y ago

nxpnsv 6y ago

Yeah, not many cyclists would add 10kg to their bike, typically resulting in doubling the bike weight.

Freak_NL 6y ago

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).

pitaa 6y ago
> 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.

orwin 6y ago

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.

wiredfool 6y ago
There's a lot of stuff in competition that's not legit.

wiredfool 6y ago

No. There’s no 30% gain to be had. Losses in a properly maintained bicycle are already far lower than this.

londons_explore 6y ago
> Losses in a properly maintained bicycle are already far lower than this. Plainly not true. If I cycle a 1 mile lap and come to a stop, I have put in lots of energy yet am in exactly the same position I started in. Bicycling (and most forms of transport) are 100% losses when considered in an "energy in Vs energy out" way.

KaiserPro 6y ago

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.

dclowd9901 6y ago
Let’s say you have two boards end to end, each on fulcrums, angled up like an A. Leading to the apex of the two boards, you have a platform at about the height of the apex. Now let’s say you to take a step forward off that platform onto the apex of those two boards at the same time, pushing them down and lifting their ends. Do you have to expend any additional _forward momentum_ energy to take that step? Now let’s say there was a big spring between the opposite ends of those two boards, and that spring just happened to compress at a weight a bit lower than force generated by you stepping onto the apex. Now, imagine stepping off the apex. As you do, you feel the apex rise and push your leg off. Now apply that mechanic around an axle, and use mechanics to ensure only the springs nearing the top of the axle (as it rotates) compress when downward force is applied to the axle itself. That’s as good as I can describe how I understand it, and I can’t see how it violates any physical laws. It’s just a clever use of springs.