Airless tires are nothing new. We've seen everything from foam
to carbon nanotubes
attempting to replace the pneumatic design but the simplicity of rubber and air always seems to win out.
Hoping to change all that is Smart Tyre Company who are bringing NASA technology to the bicycle world with a nickel-titanium alloy (also known as NiTinol+) shape memory tire called Metl that they claim "is elastic like rubber yet strong like titanium."
So, where has this technology come from? Well, Mars exploration presented NASA with a problem as it is too cold for traditional rubber tires and the solid aluminium tires used on Curiosity were prone to cracking, so a new solution had to be found. The idea of mesh tires first came with the Spring Tire in the mid-2000s that used coiled steel wires woven into a mesh pattern, however this didn't stand up to the abuse of Mars' rocky surface. It took until 2017, and a serendipitous encounter between Engineer Colin Creager and Materials Scientist Santo Padula
, for a solution to be found in shape-memory alloy nickel-titanium, which looks like chainmail but remembers its shape and returns to it after an impact.
Smart have licensed that technology thanks to a Space Act Agreement and are now applying it to a new application, bicycles. They have started with the Metl road cycling tire but claim the material can will be used for mountain bike, gravel bike and road bike applications in the future.
The tire should conform to the ground in a similar fashion to a pneumatic tyre while being immune from punctures and having a much longer lifespan than a rubber tire. Smart are also keen to push the environmental advantages of Metl. They claim that the tire industry produces '50 billion pounds [25 million tonnes] of toxic waste annually' and that using NiTinol+ presents a cleaner alternative.
There's no word on the weight of the tire but Smart claim that it is "competitive with many mainstream alternatives" and that rolling resistance is similar to a pneumatic tire pumped to 100psi. If you're worried about grip, Smart say they will coat the tires, "in a new, formulated rubber-like material, Polyurethanium, for the longest-lasting tread and grip, for all weather conditions", although there are no details on what this actually is or its efficacy.
Earl Cole, former Survivor champion and CEO of The SMART Tire Company, said: "Cyclists will not be able to wait to get their hands on these very cool-looking, space-age Metl tires that don’t go flat. The unique combination of these advanced materials, coupled with a next-generation, eco-friendly design make for a revolutionary product.”
Smart are currently testing the tire with bikes provided by Felt. Eric Sakalowsky, Felt's VP Global Marketing & E-Commerce, said, "The SMART Tire Company’s tire solution shows an exciting new frontier and we’re excited to offer our bikes to support their testing."
Smart are aiming to bring the Metl tires to market in early 2022 but further details such as pricing, tech specs or how much they weigh after a lap on a muddy trail are still to be confirmed. More info, here