FYI, reasons why air works really well as a suspension medium:
* stiffness-to-weight is high and hysteresis low. That means a) easily adjusting the compliance for different weights, b) excellent traction, since the "spring" isn't fighting its own inertia.
* in normal operations, essentially unlimited durability, because there's no long-range order to break down. Let's see how these do after a million or so cycles.
* when something does break your suspension, you're literally surrounded by the repair material. Again, let's see airless compete with that. The road is a very hostile surface. I've seen more than one well-meaning group try "ruggedised" tyres that became useless well before I'd even expect a puncture from a decent road tyre.
You're absolutely right, but I'm still happy that someone created a full-size prototype of it outside the lab, and is testing it, tinkering with it and putting it out there so people can also try it and experiment with it. I don't know what this could lead to, maybe some sort of hybrid air-filled spring loaded undestructible bike tire, maybe it's going to end-up in a completely different application, such as wheelchairs or farming tractors or mining equipment.
I'm also glad folks are tinkering. That said, bike tires are probably not where I would expect something like this to land. I would love these to replace the tires on things like utility carts, air compressors, etc that typically end up with solid tires. Those solid tires are awful, but pneumatic ones must be filled and that's annoying for infrequently used stuff.
Frankly, a tire that could maintain 80% of its performance under circumstances that a run-flat or standard tire would "blow-out" would be the difference between life and death on a motorcycle. Run-flat tires don't protect (enough) from blow-out, only puncture, which are handled well by most automotive/motorcycle tires, already. I realize the risk of blow-out is pretty low, but I've had it happen to me[0] -- regardless of how low a risk, I'd pay 4-5 times as much per tire on my motorcycle for being able to increase my chances of survival should that happen.
[0] I probably don't need to mention this happened to me in a car since I'm not writing this from the afterlife.
I have always wondered why we accept the risk of "the thing holding you to the road just falling apart underneath you". I suspected it had to be really good at what it did when it worked but wasn't sure what that is.
So, today I learned what a suspension medium and hysteresis is, but more importantly, why replacing "the tire" with something which eliminates the one safety issue would result in a number of other issues (some of which reduce safety in more serious ways than the risk of blow-out). Thanks for that!
I received a pair of Tannus Airless tires ( https://tannustires.com/ ) for christmas, and have been waiting for good weather to install them.
While they weigh more than regular tires, they weigh less than the combined weight of regular tires + pump + patch kit, so it's a net win on weight.
For me, the biggest win is not about not worrying whether or not I get a flat, it's not having to pump the darn things up week in and week out before going out on my (admittedly city commuter) rides.
The pump and patch kit are effectively static weight on a bike.
What's referred to as rotating mass on a bike (usually talking about wheels+tires) is noticeable. Maybe not as much on your city bike, but the thing that usually makes a bike feel heavy is the weight of the wheels, not the overall bike itself.
The biggest problem with airless tyres is that bumps on the road cause localised pressure changes whilst pneumatic tyres distribute those pressure changes around the wheel. In practise this means that you feel more of the bumps and for big potholes you can end up damaging the rim. There's also the problem of energy loss as part of the tyre is compressed - with pneumatic tyres you only really have the outside of the tyre that is deforming and so they have less rolling resistance.
When I tried airless tyres (a long time ago though) the ride felt very "dead" and I haven't bothered with them since.
Tubeless however - that's the best ride performance that I've tried and you very rarely get punctures that the sealant doesn't fix.
The actual weight of the tyres won't make a huge amount of difference (i.e. the rotational mass) as it only really affects accelerating which is much less common than simply maintaining your speed.
I love my Tannus tires. I spent a lot of time and money fixing flats from puncture vine (goatheads) on my road bike before getting them. I don't feel like it added much bad weight because they are so narrow, unlike my airless mountain bike tires. Well worth it.
> While they weigh more than regular tires, they weigh less than the combined weight of regular tires + pump + patch kit, so it's a net win on weight.
Larger moment of inertia, though, so not a complete win. I wonder how the trade off works--where is the breakeven point between trading tire mass for mass being carried in a fixed position on the frame?
The weight of your tires is in the worst place for rotational mass. You'll definitely feel it if you're doing city riding between frequent red lights but it could arguably be a benefit if you're cruising for long distances as it'll act like a fly wheel to some extent.
So the article says the technology was developed at NASA and then licensed to Smart via the "Space Act Agreement". It looks like the company has three patents already, one of which[0] seems (to me, after a brief glance) to cover the essential innovation behind the metal tires.
Can anyone tell me how the Space Act Agreement works? Does the innovation developed by NASA end up as a patent for a chosen company? Or do these three patents represent work done by the company and not at NASA? If it's the former, does NASA get any money from this agreement?
Ah good catch! The reason I thought the patent was assigned to the Smart company was because they list it in their Wefunder page[0] (under the heading "Key Accomplishments"). But actually all that's stated on that page is that "multiple patents protect this innovation", they don't actually claim that they have the patents.
I'm still curious how the licensing from NASA works. Do they typically grant a monopoly to certain companies or can multiple competing companies license this technology?
There are other forums in which they publish export-controlled information.
They patent things for at least two reasons. One is monetization - some in Government believe that monetization helps recoup some of the taxpayer's R&D contributions by claiming a "rightful" share of the benefits to commercial entities. I'm not saying I agree with this, just that is it a commonly held viewpoint.
Another, even in cases where the licensing is royalty-free, is for defensive purposes. It ensures a benevolent entity owns the patent and can license it for implementation in an equitable and non-discriminatory way.
Practically speaking, if you were to implement NASA-patented technology in a non-commercial context (homemade battlebot), it's extremely unlikely NASA would come after you for patent infringement.
In a way, yeah it is a better spring steel. Many shape memory alloys, besides their famous shape-changing-under-heating behavior, can also have superelastic properties, meaning they can reversible handle much larger strains than typical alloys (by a reversible phase change in the material). This means they can work as a better spring alloy. https://en.wikipedia.org/wiki/Pseudoelasticity
Nitinol typically has tight compositional tolerances and is used for things like stents and catheters. It's nothing new in the medical field. But it'd be pretty damn impressive to manufacture something so finely structured out of nitinol at scale.
I wonder, though, if the rubber can be more rugged as a result.
Materials/chemistry is so far out of my wheelhouse, I can't even imagine what that might be. But I'd imagine there might be a way to optimize the synthetic rubber for handling friction against the road surface while not having to optimize it for handling pneumatic pressure.
Unfortunately, I suspect that the things done to make the tire survive road friction better also make it grip the road worse. And that there's likely not a chemical formula that one can apply which wouldn't work equally well under a pressurized tire... but hey, most things are evolution, not revolution, anyway, right?
I could see these being much better for mountain bikes than for road bikes as the woven surface might actually improve traction on mountain bike trails.
I usually try to stay open-minded towards any new inventions, but there have been sooo many failed attempts at replacing pneumatic rubber tires that I'm very skeptical whenever a new one is made. Best of luck to them, but I'm not holding my breath.
Not to mention that if bicycles ever get something like this it'll be 30yr after applications where puncture resistance is a high priority (i.e. everything you see using solid tires today) gets them.
The bicycle itself is highly resistant to change as well. The overall concept basically hasn't changed for over a hundred years. Just small tweaks here and there.
Oddly enough the human body also hasn't changed much. I've noticed this in some other technologies as well, such as the electric bass guitar, which I play. The electric bass settled on a fairly standardized geometry within a few years of it being invented. And while there have been some experiments and oddball instruments made over the years, the bread and butter instrument still looks pretty much like the original Fender bass with some tweaks. I've tried some of the modernizations, and they're physically awkward to play. There was a period of basses with sexy long necks and tiny little bodies, and they all suffered from "neck dive."
Still, while I ride a bike that would not have looked out of place in 1890 when viewed from a distance, on closer inspection a lot of things have been improved. Perhaps most importantly, all of the newer materials are better, including high performance steel, aluminum, tires, and so forth. Hydroforming and carbon fiber layup have finally made it possible to experiment with more interesting frame shapes.
That’s mostly because the UCI has very strict rules about bicycle design. They banned recumbent bikes very early in the history of the sport; more recently they banned Graeme Obree’s “superman” position and other changes to the geometry of a normal upright.
Check out Mike Burrows for some interesting bike designs. Check out the Battle Mountain speed records for what the highest performance bikes look like.
If you want background on the material in question here (nitinol), The Verge had a good video explainer about the material and a bit about how the “space tire” aspect will work. It’s really a fascinating video of you’ve never seen the metal in action. I can see why it would be chosen for the environment on Mars. I’m not sure if it would be better than air tires on Earth, but for the low atmosphere environment on Mars, it makes more sense.
And can someone explain to me what "shape memory alloy" means in this context? Iirc that means a metal that will return to a shape when heated. So I blowtorch these bike tires every few days to iron out dents? Or are these just spring steel, metal that bounces back into shape so long as it isn't push beyond its yield point?
Woven metal tires are old. And nitinol is also old (it was not developed for the rover, a wiki check would show as much).
But the combination is new. I imagine the conversation went
'hey I am working on chainmail tires'
'areny those heavy'
'well. We need them light, strong and elastic, and you only get two...'
' hol up, there is an option, you heard of nitinol?'
They developed the shape memory part recently while developing a new wheel for the Mars rover.
From your NASA link:
“ In one particular moment of serendipity, Engineer Colin Creager and Materials Scientist Santo Padula had a conversation that completely changed the path forward.
The game changing material that dramatically advanced the development of spring tires was nickel titanium, a shape memory alloy with amazing capabilities as explained by Santo Padula.”
Nickel-titanium ("nitinol") shape-memory alloys are also "superelastic", which means they have an additional range of deformation past normal elastic deformation before plastic deformation from which they return back to their original shape. So, not just spring steel.
Not a shape alloy expert, but the temperature that causes them to morph can be manipulated when they're formed (forged?). I have a few strands that just the heat from your hand is often enough to trigger them.
So, the heat from friction is potentially an option.
Have you been converted to the cult of tubeless tires? They truly are remarkable. I ride on sharp limestone and thru hedgeapple rows, and the fact these things hold any sort of air after a ride is truly amazing. I was so mesmerized by the performance on my mountain bike, my 'city' bike now sports tubeless rims and tires. I haven't had a flat yet! (knock on wood, headed to Bentonville next weekend).
To me, this problem is mostly 'solved' unless there's a generation leap in weight savings. My tires weigh .65kg each (and thats light for MTB)! That's a lot of rotating mass that's also unsprung on the suspension.
Readit News
* stiffness-to-weight is high and hysteresis low. That means a) easily adjusting the compliance for different weights, b) excellent traction, since the "spring" isn't fighting its own inertia.
* in normal operations, essentially unlimited durability, because there's no long-range order to break down. Let's see how these do after a million or so cycles.
* when something does break your suspension, you're literally surrounded by the repair material. Again, let's see airless compete with that. The road is a very hostile surface. I've seen more than one well-meaning group try "ruggedised" tyres that became useless well before I'd even expect a puncture from a decent road tyre.
[0] I probably don't need to mention this happened to me in a car since I'm not writing this from the afterlife.
So, today I learned what a suspension medium and hysteresis is, but more importantly, why replacing "the tire" with something which eliminates the one safety issue would result in a number of other issues (some of which reduce safety in more serious ways than the risk of blow-out). Thanks for that!
While they weigh more than regular tires, they weigh less than the combined weight of regular tires + pump + patch kit, so it's a net win on weight.
For me, the biggest win is not about not worrying whether or not I get a flat, it's not having to pump the darn things up week in and week out before going out on my (admittedly city commuter) rides.
What's referred to as rotating mass on a bike (usually talking about wheels+tires) is noticeable. Maybe not as much on your city bike, but the thing that usually makes a bike feel heavy is the weight of the wheels, not the overall bike itself.
Best of luck with them.
When I tried airless tyres (a long time ago though) the ride felt very "dead" and I haven't bothered with them since.
Tubeless however - that's the best ride performance that I've tried and you very rarely get punctures that the sealant doesn't fix.
The actual weight of the tyres won't make a huge amount of difference (i.e. the rotational mass) as it only really affects accelerating which is much less common than simply maintaining your speed.
Deleted Comment
Larger moment of inertia, though, so not a complete win. I wonder how the trade off works--where is the breakeven point between trading tire mass for mass being carried in a fixed position on the frame?
the issue with airless tires though is bot weight, but rolling resistance and handling. Both are much worse. It is going to feel horrible.
Can anyone tell me how the Space Act Agreement works? Does the innovation developed by NASA end up as a patent for a chosen company? Or do these three patents represent work done by the company and not at NASA? If it's the former, does NASA get any money from this agreement?
[0]: https://patents.google.com/patent/US10449804B1/en
What do the company’s patents say and detail?
I'm still curious how the licensing from NASA works. Do they typically grant a monopoly to certain companies or can multiple competing companies license this technology?
[0]: https://wefunder.com/the.smart.tire.company
Our tax dollars paid for it, our homemade battlebots should be armored by it.
There are other forums in which they publish export-controlled information.
They patent things for at least two reasons. One is monetization - some in Government believe that monetization helps recoup some of the taxpayer's R&D contributions by claiming a "rightful" share of the benefits to commercial entities. I'm not saying I agree with this, just that is it a commonly held viewpoint.
Another, even in cases where the licensing is royalty-free, is for defensive purposes. It ensures a benevolent entity owns the patent and can license it for implementation in an equitable and non-discriminatory way.
Practically speaking, if you were to implement NASA-patented technology in a non-commercial context (homemade battlebot), it's extremely unlikely NASA would come after you for patent infringement.
It's also kind of funny that they admit they'll have to wrap the metal in a rubbery substance for traction.
So we're pretty much back at steel radial tires.
Materials/chemistry is so far out of my wheelhouse, I can't even imagine what that might be. But I'd imagine there might be a way to optimize the synthetic rubber for handling friction against the road surface while not having to optimize it for handling pneumatic pressure.
Unfortunately, I suspect that the things done to make the tire survive road friction better also make it grip the road worse. And that there's likely not a chemical formula that one can apply which wouldn't work equally well under a pressurized tire... but hey, most things are evolution, not revolution, anyway, right?
Still, while I ride a bike that would not have looked out of place in 1890 when viewed from a distance, on closer inspection a lot of things have been improved. Perhaps most importantly, all of the newer materials are better, including high performance steel, aluminum, tires, and so forth. Hydroforming and carbon fiber layup have finally made it possible to experiment with more interesting frame shapes.
http://www.wolfgang-menn.de/superpos.htm
https://www.bikeradar.com/features/top-five-banned-tech-the-...
Check out Mike Burrows for some interesting bike designs. Check out the Battle Mountain speed records for what the highest performance bikes look like.
https://www.theverge.com/2021/3/17/22334611/nitinol-metal-sh...
https://youtu.be/Pn-6bGORy0U
https://airandspace.si.edu/collection-objects/wheel-lunar-ro...
https://www.nasa.gov/specials/wheels/
And can someone explain to me what "shape memory alloy" means in this context? Iirc that means a metal that will return to a shape when heated. So I blowtorch these bike tires every few days to iron out dents? Or are these just spring steel, metal that bounces back into shape so long as it isn't push beyond its yield point?
But the combination is new. I imagine the conversation went 'hey I am working on chainmail tires' 'areny those heavy' 'well. We need them light, strong and elastic, and you only get two...' ' hol up, there is an option, you heard of nitinol?'
And thus, cool history.
From your NASA link:
“ In one particular moment of serendipity, Engineer Colin Creager and Materials Scientist Santo Padula had a conversation that completely changed the path forward.
The game changing material that dramatically advanced the development of spring tires was nickel titanium, a shape memory alloy with amazing capabilities as explained by Santo Padula.”
Short answer is that the material is super elastic, and will return to its original shape either when heat is applied, or when stress is applied.
So, the heat from friction is potentially an option.
To me, this problem is mostly 'solved' unless there's a generation leap in weight savings. My tires weigh .65kg each (and thats light for MTB)! That's a lot of rotating mass that's also unsprung on the suspension.