This is a space-themed announcement as the Los Angeles based SMART Tire Company is associated with NASA in the development of Shape Memory Alloy Radial Technology (SMART). These are airless tyres created from a Nickle Titanium weave and coated in (rubber-like) Polyurethanium. The company predict that their METL™ tyres for bikes could be available for purchase as soon as next year.
There is a lot to uncover with this announcement… we already have tubeless tyres, but airless sounds good. To date the main airless options are the Tannus foam tyre and the newer Schwalbe Airless system (foam insert) and these are followed by a swarm of lesser known foam tyre brands. The only time that metal really makes an appearance on the rolling surface of bike tyres are on historical bicycles (wooden construction with the metal band) or studded tyres for snow and ice.
The origin of this technology is indeed the development of wheels for the NASA Mars Rover. The R&D was undertaken at the NASA Glenn Laboratory in Ohio and this Shape Memory Alloy (SMA) tech is destined to be used on the Mars Rover planned for the 2026 Mars Mission launch. The SMART Tire Company is an official licensee of the SMA tech and is gearing up for a big round of ‘crowd sourced equity’ and they are also current seeking (USD) $100,000 on a US platform funding platform.
The business plan suggests that they will enter the market with a “high-end bicycle tire that establishes the value of shape memory alloy tires” and then they move into the micro-mobility markets and try and bring down costs to move into truck and automotive wheels.
Future tech today
In the 1992 Sci-fi novel by Neal Stephenson, one of the fantastical visions (beyond the Metaverse) were tyres with telescopic metal rods that could predict the surface and deal with grip, traction and suspension. One of the NASA wheel prototypes from this research features radially extending ‘wires’ however the METL tyre for bikes appears to be more a a woven structure.
Grip and traction are my first concern, I wouldn’t fancy my chances of steering at speed. However the NiTinol+ (Nickle Titanium) material is coated in a rubber-like Polyurethanium. Yes… I suppose that would work.
The properties are described as “Smart memory metal that (unlike stretching) rearranges its molecular structure when you bend it, but instantly goes back to its original shape, perfectly”
Does it really ‘rearrange the molecular structure’? My material science studies (which are admittedly not particularly advanced) would suggest that the inherent properties of the Nickle Titanium alloy and the right construction could lend the ‘Smart Memory Metal’ properties that would help it return into position and help with shock and vibration absorption. Perhaps it is a cool way to describe it, but maybe it is not unlike a spring or any other material that can accept flex and can return to the original form or shape.
From the outset, an airless tyre is the obvious feature. No more pumping up the wheels and the metal will likely provide great protection against glass and debris that may otherwise puncture a traditional tyre.
The construction could also be ‘optimised’ like a carbon fiber bike to control the ride qualities, the balance between stability with compliance could be built into each tyre.
Th METL tyre could also be a more environmentally friendly solution compared to the traditional manufacture of tyres and also considering the lifespan and disposal. With the claim “One tyre for the life of the bicycle” and the potential to recycle, the ecological balance could be better than traditional rubber tyres.
Felt Bicycles are listed as a partner and the interest in the bike industry in new tech will mean there will be a lot of watchful eyes… but it will have to prove itself.
Even with a rubberised coating to provide grip, the form of the tyre means that the total contact surface area with the road is much smaller and this opens up questions about grip, handling and rolling resistance. The aerodynamics and the behaviour when riding in the rain are also unknowns… the Mars Rover is not known for land speed.
Smart Tire Company projects that they could be able to challenge (and take on) 9% of the bicycle tyre market. There will probably be a few iterations until this is really ripe and can reach this level of adoption. Simply consider the tremendous range and style of bicycle tyres already on the market today.
It is not yet known how the tyres are mounted. Will they behave like a clincher with a comparable design and properties allowing it to lock into place on the rim, or will other mechanical fastenings or even a unique rim be necessary to use these SMA tyres?
Will these tyres suffer fatigue and will they behave like regular tyres on different surfaces or when facing obstacles? What happens when the surface coating or even the metal wears, is a new surface coat an option? Will debris and small stones get stuck inside and will there be special maintenance or care.
Could rim and disc brakes be eliminated if the tyre itself can be used as a braking surface?
And do they have a Gravel version? But seriously, grip and road handling of regular tyres are influenced by tread (among other things) so can tread be included?
This is a technology I will keep my eye one. I assume that if they succeed and produce the first round of commercially available tyres, they will have a royal price tag. The results from the first ‘real’ riding tests will reveal if this concept for bicycle tyres will change mobility forever… or should we just wait for hover boards to arrive?
Photos © SMART Tire Company