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Airless Bicycle Tires Using NASA Tech, Up On Kickstarter

It's like a spring bent into a donut shape

By Rain Noe - September 14, 2023

in Bikes

A startup called the Smart Tire Company has licensed NASA's airless tire technology, and adapted it for bicycles.

NASA's non-pneumatic wheels, intended for interplanetary rovers, look like this:

These "shape memory alloy radials" rely on the spring-like strength of alloys, rather than air, to provide the cushioning and deformability required of a tire. Initially, the Smart Tire Company used the concept to design this wheel for a gravel bike:

They've now refined and simplified the design into this METL wheel below, which essentially uses a spring, wrapped into a torus shape, to provide the structure for a wheel:

That wheel is then clad with a replaceable rubber tread, which requires 50% less rubber than a conventional bike tire:

The METL wheels work on standard bike rims, and the company reckons their NASA technology means they'll succeed where others have failed:

Airless tires sound great, but they usually fail to deliver…. Major tire companies have mostly given up on airless applications altogether: the ride is rough, and/or it's more work to pedal (high rolling resistance). Why? They're using the wrong materials, stuck in the era of rubber and plastic.

METL tires are powered by an inner skeleton made from a modern material called Nitinol, a shape memory alloy. It's a lightweight, highly flexible "superelastic" metal that stretches like rubber, but is strong like titanium [and] will always instantly snap back into its original shape.

Nitinol/SMA properties include:

- The highest energy return of any material previously used in any tire (fuel efficient, lower rolling resistance)

- Shock absorption & elasticity (smooth ride)

- Extreme durability, but still lightweight, due to unique properties of the material

- SMA tire internal structure can last the life of your vehicle, so one set of tires is all you'll ever need

Save TIME & MONEY with zero flats, no air pressure to check, no sealants, no inserts, no foams, no patches, no spares, no expensive replacements, and no more being stuck in the middle of nowhere carrying or walking your bike. No more worries. Just ride.

The company says the METL wheel is suitable for pavement or gravel. They're manufacturing a limited run and selling them through a Kickstarter campaign, which has already been successfully funded, with 27 days left to pledge at press time. Buy-in starts at $500 for a pair of METL wheels with no rims, and $1,300 for a pair that come with aluminum rims. They're also offering pricier carbon fiber rims starting at $2,300.

The METL wheels are expected to ship in June of 2024.

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Zach W

a year ago

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So I pop a standard rubber tire, I buy a new one for $30... I bend one of these spring tires and what, have to buy a whole new tire? The kickstarter has 2 tires at $500.... eventually they WILL bend or break and that's a pricey fix. Also how do they do with temperature changes? winter to summer?

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- Dee An
  
  Zach W
  
  a year ago
  
  Z
  
  Z
  
  Reply
  
  Never pay too much attention to the cost of a new product, it will always come down over time.
  
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Ryan Cee

a year ago

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1Z

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Airless tires don't work well and never will because they function optimally for exactly one loading, and there's no way to adjust them for ride quality or handling style like there is with pneumatic tires. Also, there's already tubeless/solid tire brands out there and they sell for a tenth of this.

Additionally, NASA uses this design of wheels and tires because they weigh less than a standard pneumatic tire and function good enough for their purposes. It's about reducing lift mass, not making a better tire.

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Sean Horita

a year ago

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I don't see what the equivalent psi to an air-filled tire is. Which is important, because people and bikes weigh different amounts!
Also don't see a promo video of anyone riding their product on a bike the way bikes are actually ridden. 5mph in a conference hall doesn't constitute real-world. How well does it corner downhill?

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Christian Lockenwitz

a year ago

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Ah yes, but all that doesn't matter: They're really good-looking!

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Mike Cheung

a year ago

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I've used tubeless for years with no issues and minimal maintenance. I have Stan's inside tubes on my commute bike, again zero problems commuting daily. I think I have nearly 7k miles on my current tubes with no flats. Seems like solving a problem that's not really a problem.

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- Dee An
  
  Mike Cheung
  
  a year ago
  
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  Z
  
  Reply
  
  Yep, my friend says he doesn't bother carrying a spare inner tube or patch kit on his daily cycle commute these days - modern tyres are that good at preventing punctures.
  
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