NASA-Inspired METL Bike Tires Promise a Flat-Free Ride, Powered by Shape-Shifting Metal

The Ohio-based Smart Tire Company wants to change the bicycle tire game with its new airless bicycle tires. Specifically, the METL bicycle tire uses the NASA-developed shape-memory alloy (SMA) known as nitinol. And the company is setting our expectations high, claiming its product is "The Holy Grail of Cycling." Before I tell you more about it, let me briefly explain the science behind nitinol.
METL Bike Tires 22 photos
Photo: Smart Tire Company
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Nitinol's origins date back to 1959 when Dr. William J. Buehler created it by mistake with a 55% nickel and 45% titanium mix. Perhaps the most valuable property of this alloy is its two-way shape memory effect. To put it simply, during low temperatures, nitinol bends easily, rearranging its molecular structure. However, when it's heated up, it recovers its previous shape. What's more, it can withstand more significant strains (30x higher recoverable strain than steel) than ordinary materials without suffering permanent deformation.

This property meant that nitinol could be used in NASA rover tires, as they could withstand freezing temperatures, won't go flat, and could envelop obstacles all the way down to the rim without plasticizing the material.

Nitinol can and has been used for various other purposes, such as constructing F-14 fighter jet wings, developing flexible eyeglass frames, or in the medical field to make stents. The METL bicycle tire will be the first consumer product to use nitinol, and its maker says the tires will last a lifetime, never going flat. Such a claim is hard to ignore.

The Smart Tire Company has a Space Act Agreement with NASA and an exclusive license to develop and commercialize the superelastic tire. The SMA tire technology has been in development for over 12 years, with more than $10M in government funding and research.

METL Bike Tires
Photo: Smart Tire Company
Smart Tire Company has been working on the METL for quite a while, and it says that more than 10,000 cyclists are signed up on its waitlist. But here's where things get a bit risky – the company is selling the tires through a crowdfunded campaign on Kickstarter.

If you're familiar with Kickstarter, you know the projects there can be a hit or miss. These projects often run into delays and missed deadlines, and many end up not even being finalized. Moreover, when you back a product on Kickstarter, you're not necessarily buying it, as the platform's policy states that Project Creators may cancel or refund a pledge at any time for any reason, and they do not have to fulfill the reward. That doesn't mean you can't find genuine and successful projects - I've personally backed a project on Kickstarter, and I'm happy with the product I received.

With this disclaimer out of the way, let's take a closer look at the METL tire. The product aims to make cyclists' lives easier by eliminating the possibility of flat tires. Of course, that's already been done with airless tires, but they come with a few downsides, such as a rougher ride and increased rolling resistance.

METL tires feature a spring made from Nitinol that runs around the tire. It's encased in a poly-rubber material forming the tire's transparent sidewall and replaceable thread – the company claims this setup uses half as much rubber as a regular tire. As more than a billion tires reach their end-of-lie per year, it's refreshing to see products that keep sustainability in mind.

METL Bike Tires
Photo: Smart Tire Company
Indeed, the thread needs to be replaced roughly every 5,000 to 8,000 miles (8,047 to 12,875 km), but the company claims the main tire should last for the bike's life. Oh, by the way, rethreads are priced at $10 (€9.4) per tire.

Smart Tire Company will offer road/gravel METL tires in size choices of 700 x 32c, 35c, and 38c, with medium-low rolling resistance. Moreover, they're manufactured in the United States and tip the scales at around 450 grams (almost 16 ounces).

Smart Tire Company says that its tires are "DIY easy install" onto most common gravel or road bikes. Furthermore, they're designed to offer a lightweight, smooth ride with superior handling and durability, as well as increased traction compared to typical air-filled tires. Believe it or not, its maker claims it has even shot a bullet through the tire and kept riding.

METL Bike Tires
Photo: Smart Tire Company
Of course, as you'd expect, these tires don't come cheap, especially compared to conventional tires, even the high-quality ones. Two METL tires go for $500 (€469), with two choices of color: blue or clear. Other options are available, such as two METL scooter tires for $150 (€141), a METL wheelset with the tires and two aluminum wheels, and another wheelset with two carbon fiber rims.

If the technology does reach production, delivery is scheduled for June next year. As of now, 140 backers have pledged $73,265 (€68,672), significantly surpassing the project's $25,000 (€23,433) goal. In fact, it took just 18 minutes for the funding goal to be met. Plans for the Smart Tire Company include developing wider METL tires for MTBs and e-bikes.
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About the author: Mircea Mazuru
Mircea Mazuru profile photo

Starting out with a motorcycle permit just because he could get one two years earlier than a driver's license, Mircea keeps his passion for bikes (motor or no motor) alive to this day. His lifelong dream is to build his own custom camper van.
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