It will take something special to unseat rubber and air from their perch atop the tire hierarchy.
A company founded by a “Survivor:Fiji” winner and built on technology originally developed for NASA’s various space rovers is the latest to give it a go. The Smart METL tires are, as the name suggests, made of metal, specifically, a nickel-titanium alloy called NiTinol+ arranged in a series of interconnected loops or springs that looks a bit like medieval chainmail.
The material itself is the key innovation. It’s a “shape memory alloy” created by NASA engineers Dr. Santo Padula and Colin Creager and is capable of deforming and returning to shape without losing structural integrity. The material and design were developed for to NASA’s Mars rovers, which need to function on a planet too cold for rubber tires.
The material and chainlink design allow the tire to deform over obstacles like a pneumatic tire, then return to its original shape. It’s immune to punctures, of course, and the company also claims the design is more environmentally friendly relative to the “50 billion pounds [25 million tonnes] of toxic waste” that the Smart says the traditional tire industry generates annually.
Smart licensed the tech via the Space Act Agreement, which is intended to help NASA technology trickle out into the commercial world. The company shifted focus to bike tires and already has a partnership with Spin, a micromobility company owned by Ford. Testing is currently being conducted on a fleet of bikes provided by Felt.
So will it work for bikes? Well, performance details are scarce. The company didn’t release weights. Smart claims rolling resistance is comparable to a pneumatic tire at 100psi, but as all good tire nerds know, that’s quite a range. Are we talking about a fast race tire at 100psi, or a commuter tire at 100psi?
Other major questions remain unanswered. Would the METL be tuneable for different rider weights?
Anybody who has had the misfortune of riding any distance on a tire-less rim knows that metal and pavement aren’t a particularly grippy combination. To combat this, Smart says they’ll wrap the METL in a rubber-like substance called Polyurethanium. We have no idea what this is and Smart provided no detail.
Historically, airless tires have been nasty, bumpy, gripless things best avoided unless you commute on piles of glass. But the flatless bike tire, particularly given the rise of ebikes as car replacements, remains an exciting prospect. Smart may have taken their PR photos on a triathlon bike, but that’s not where this solution is truly needed.
Those of us deep in the cycling space probably know how to fix a flat, but it can be a daunting problem for many, one more thing keeping them off bikes. Perhaps Smart has the answer.