Smart METL airless metal bike tires use a “shape memory alloy” for deformation
cyclingtips.com
cyclingtips.com
* 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.
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.
[0] I probably don't need to mention this happened to me in a car since I'm not writing this from the afterlife.
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.
I'm about to replace the tyres[0] on mine in a month and I'm researching the safest options.
[0] British, mate?
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...
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.
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.
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.
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?
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?
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].
1: https://www.federalregister.gov/documents/search?conditions%...
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?
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.
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.
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.
https://www.theverge.com/2021/3/17/22334611/nitinol-metal-sh...
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?
So, the heat from friction is potentially an option.
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.
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.”
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.
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.
Do things get trapped in there? Is it like a mix-master with thick dough and it gets all clogged up and you better wash it before lumpy things harden?
Given that the mesh has an uneven surface though, I don't see how they could compare well to the resistance of a tire with a smooth surface.
Also, it looks like the coating would have to be reapplied often because it's so thin.
And small objects could start to accumulate inside, no?
The more I think about them, the more impractical they seem. Would still love to try them though.
Also I'd be really concerned about how much grip it'd retain on a sandy concrete corner..
That was funny. The bad news: polyurethane is a type of plastic, already used as a replacement for rubber in some kinds of tires.
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.
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.
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.
"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.
Surely there's a real word they could use there.
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".