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.
Agreed. I happen to enjoy the hobby of tinkering with old bikes, so my bikes are typically a few decades behind the latest technology. So I can adopt a wait-and-see philosophy.
But still I remember a cynical comment by my dad, maybe 40 years ago. They had just announced some new advanced material, and my dad said: "Mark my words, the first applications will be high end bikes and golf clubs." Also, improving on the bicycle is a very common capstone project for design students.
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.
It's an interesting idea, but the fraction of motorcycle fatalities caused by blow-outs is so minuscule it's far more likely the decreased performance overall of this tire would cause far more.
Unless you are assuming equivalent performance, which seems unlikely. Modern motorcycle tires are incredibly good, even (with appropriate ones) in rain.
I got a rear puncture on my GSXR1000 while riding 100kmhr through the countryside.
Straight was only slight issue, I noticed somethnig seemed a bit weird but road had minor undulations and I slowed a bit to 80. Slight turn though was quite wobbly so I stopped. Tyre gauge said less then 20psi, flat as it gets.
That I could ride in a straight line with such stability was amazing testament to the tyre.
I limped 30km to nearest town at 30kmhr or so. Slow but doable.
Would I want to do this again? No, of course not. But that I could? Amazing.
I agree that tyre performance > runflat as priority.
No, the tyres were not runflat. They were Michelin Road 2. Sports touring-ish tyres.
But I suspect most modern radials would have performed similar.
Few caveats:
- a GSXR being a sports bike doesn't carry a lot of weight on the rear, until you accelerate hard. I suspect a cruiser style bike might have struggled more. Especially if with a pillion or loaded up with luggage.
- a flat tyre does deform a lot! It wasn't enjoyable riding! It wiggled and jiggled the whole way, only a little on the straight, much more on even a slight turn.
- my 30kmhr speed was because the GSXR1000 1st gear meant the engine idled at 20kmhr and so was on the verge of stalling. I picked minimum above that.
- After the 30km I had wrecked two strips either side of the main middle strip. I guess the middle strip didn't take much weight and flexed out of the way a lot (like a "W" shape) hence heating and ruining the two strips of rubber either side.
- I got a plug to get me 200-ish km home (cruising at 100kmhr again but otherwise being gentle, no hard acceleration or cornering) and then that tyre got replaced as soon as I could get it into a shop.
Am Australian.
Maximum safety means different things to different people. Around the city, something that handles the wet and has good grip. Your regular multi-compound (harder middle, softer edges) tubeless.
If I were tyre shopping for "maximum safety" for long cruising trips into the Outback etc with fully loaded bike. Maybe a tyre that takes a tube, and carry a spare tube, tools and knowhow to use them.
Much happens nowadays with a simple good modern tubeless tyre, a $1000 emergency budget and a mobile phone. If going really far out, an epirb or satellite phone or similar.
Edit: forgot to mention, some people think Slime and a pump might be an option. Hand pumping a motorbike tyre from truly flat though might take a while! Might want at least a foot pump or a small compressor...
But the point is that modern multi-compound radial tyres ARE really quite good. Even my tyre puncture was a nail, likely from leaving the town before I noticed the flat...
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?
It depends. NASA will file a notice of intent to grant an exclusive or partial license - you can see the notices here[1].
In this case it seems the patent is still available for anyone to license[2]. They have special licensing terms for startups that are pretty favorable[3].
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.
There are a lot of alternative bike geometries that go a lot faster than the standard bike position. They reduce wind resistance and/or have better biomechanics. The lack of change has more to do with Union Cycliste Internationale rules than with optimization.
Indeed, and in fact I see a lot of recumbents in my locale on the longer, flatter bike paths. Not so much in urban traffic. So a bike that's adapted to the human body doesn't mean there's not a better adaptation for some uses.
And I'm certainly not averse to trying one someday -- N+1 and all that. There's a shop in my locale dedicated to them. However, I think the mass market for bikes has diverged from the racing world. Most bikes sold today are of styles such as cruisers, hybrids, and low tech mountain bikes, that are unrelated to racing categories. Even many racing style bikes such as gravel and cyclo are bought with the intention of using them "off label" if you will, just because they look comfortable and rugged. So the UCI isn't holding us back any more.
Hell, there's the whole category of e-bikes. That's probably the biggest threat to the market for more efficient human powered bikes.
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.
I guess if the metal is doing 99% of the support work, then you might be able to "spray on" grip.
This might be SUPER IMPORTANT if it's biodegradable, with all the stories about the noxious effects of car tire wear particles impacting the environment.
Since the "grip" doesn't need to do the support job, we can use a more fragile compound.
One of the simplest and most common mods to off-road vehicles is called a tire mousse. It's basically foam or rubber that replaces the inflatable tube. The benefits are never getting a flat, and not having to carry a spare tube, tools, or patches. There's some efficiency loss which may be too much for a commuter bicycle, but it looks like they exist for mountain and e-bikes.
Yet another solution looking for a problem to solve. We don't need better tires. We have them. They're called 'pneumatic' and in the late 1800's they were a significant advancement in technology. They provide a great ride, great traction, and are straightforward to repair. I seriously doubt whether "Smart METL" airless tires meet those same marks.
I think there are significant usability problems with wheels and tires that can be tackled.
For example, tires lose air on a daily basis and have to be pumped up. Additionally, even the best pumps require a bunch of fidding to attach and detach the hose to the air fitting.
Tires and suspension are a tradeoff between comfort and efficiency. Lower rolling resistance means a stiffer/harsher ride. High pressure tires are narrow, have a very small contact patch and no "suspension travel"
Even though it's cliche, I think reinventing the wheel might take us interesting places.
Repair isn't that straightforward. It requires you to remove the wheel, and then the tire. You then replace the inner tube and re-mount the tire bead, which requires some practice to get right. Then you have to re-pump it. An expert can do it quickly, but it's a hassle for an amateur out for a cruise.
It's also limited by the tubes and/or patches you've brought with you. If you blow a tube, you should have a spare. If you lose a second tube, you may be out of luck. Maybe it can be patched, though I've found patching unreliable. You may be in for a long walk, in your cycling shoes -- especially if you've ridden out of cell phone range.
These are clearly going to be far beyond the price point of your casual rider, at least for a while. But if they can match the ride experience, and eventually lower the price, I could see these being wildly popular.
Pneumatic tires are hard to beat, but there's a lot of room for improvement in their durability. Which is really important for something you depend on so much.
Why spend $20 when you can spend many times more for the product without any real benefits.
"Polyurethanium" - when normal tire wears off you just replace single piece of rubber, when this adamantium dies one will have to replace that whole metal wonder.
Yes on a regular bike you replace cheap (sometimes not) tire. With this contraption they put tire / protective layer on top of their metal wonder. Problem is that this protective layer will wear in no time and then you will have to replace the whole metal piece which is expensive proposition.
And every such name is just waiting for someone who has a bad experience due to a flaw, and christens it 'Stupid'. To avoid this phenomenon name your "Smart Pointer" "RefCountingPointer" not "SmartPtr".
Like unobtanium? If they use a real word, they wouldn't be able to trade mark it and protect their brand. Sounds like people are taking cues from big pharma with naming, or silicon valley by taking real words and dropping vowels. It's a trend. Why is this surprising to you?
Also, if this is some kind of polyurethane, they're going to have a hard time convincing anyone that this is an environmentally friendly alternative to rubber tires.
I kind of takes tires for granted in a lot of ways. My assumption was that technology around the "tire" wasn't going to change substantially any time soon and there has to be a number of very good reasons I'm unaware of as to why we accept the risk of blow-out for the remaining benefits of the technology (the article mentions road grip, but yodelshady in the comments mentioning suspension medium explained the reasoning really well).
A lot of thought has been put toward reducing "blow-out" and other risks associated with "rolling around on a balloon". I started looking at "run-flat tires" after having suffered a blow-out on the road at 70MPH on defective (two-day old) tires and experiencing what it really is like to have your life "in God's hands" for twenty long seconds. I was in my car, that time -- had it been a blow-out on my motorcycle...
After some research and discussion with a trusted mechanic, I opted to save $100-or-so/tire[0] and skip the technology. I wanted tires that I wouldn't have to concern myself with the pressure, I was being sold tires that handle a nail pretty well.
Having suffered a blow-out in a car, it's something that's on my mind on my motorcycle. There's just not a lot you can do -- the best tires are designed to prevent the typical causes of this but defects in the tire/chemicals involved can make it impossible to verify that the tire is safe to ride on prior to use for certain defects. Some won't be an issue until the tire has been driven at speed enough for it to reach a certain temperature (that was my issue) and there won't be a scar or bubble on the tire where it's about to fail.
So all of this to say -- this looks like a really excellent thing if they can truly eliminate pressurized air and maintain the performance of a regular tire (while not costing an unrealistic amount -- that's probably tricky). I doubt it would "eliminate the tire" in every application -- it makes sense to start with bikes -- but I'll be an early customer when they have a motorcycle tire replacement. :)
[0] His explanation was that they'll let you get to the shop if you "roll over the business end of a screw". Regular tires are designed to handle punctures gracefully, already. Run flat will do a little better than a regular tire but they blow out, especially if the car doesn't have a pressure monitor because the tires don't appear to be as low as they are, causing the driver to damage the tire rapidly. He also confirmed my suspicion: "It's a pretty safe bet that if the tire has 1,000 miles on it, it won't blow out until after you should have replaced it" -- basically, brand new and really old tires are the ones that just spontaneously "fall apart".
* 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.