Weight Weenies Wowed By Bicycle Inner-Tubes Spun Off From Cellphone Tech

“Build a better mousetrap, and the world will beat a path to your door,” opined the nineteenth-century American essayist Ralph Waldo Emerson. Almost. His actual quote is less pithy—“If a man can make better chairs or knives than anybody else, you will find a broad hard-beaten road to his house”—but the sentiment stands: improve a mundane product, and you’ll sell shedloads.

You can’t get much more mundane than the bicycle inner tube. Made from butyl, a form of synthetic rubber, the standard inner tube is ubiquitous, keeping comfort- and speed-enabling air inside billions of bicycle tires around the world.

There are market challenges to this ubiquity. Some bike-share bicycles, from the likes of Chinese “dockless” operators Mobike and Ofo, are equipped with microcellular “solid” airless tires; high-end road-racing bicycles have long been shod with one-piece tubular tires which require no removable inners; and many mountain-, gravel- and road-bikes combat flats with automotive-style “tubeless” tires.

Despite these competing technologies the bicycle inner tube—developed in 1889 by French rubber entrepreneurs Édouard and André Michelin, and which the brothers would adapt for cars but not until six years later—still rules the roost.

Gram-counting cyclists—known to themselves and others as “weight weenies”—often favor natural rubber latex inner tubes, which are lighter and more expensive than butyl tubes, but they are not airtight, requiring daily inflation.

But there’s now an inner tube material that’s much lighter and stronger than butyl, and lighter and stronger than latex but with better air retention.

This new material is also said to offer lower rolling resistance, the force resisting motion when a tire rolls, and, being lighter, also significantly reduces rotating weight, a major go-faster benefit. The material is a Thermoplastic Polyurethane Elastomer, or TPU.

TPUs combine the rigidity of thermoplastics, such as plastic bottles, with the elasticity of rubber bands.

This particular TPU—colored orange for brand awareness—was introduced to the bicycle market in 2016 by Austrian startup Tubolito. Before being repurposed for inner tubes, the material was being used, in small quantities, as an acoustic membrane inside cellphone loudspeakers.

Its potential for use inside bicycle tires was spotted by Christian Lembacher, then a materials scientist for an audio company that makes membranes for Samsung and other cellphone companies. (Lembacher’s name appears on multiple patents for acoustic membranes.)

Lembacher realized this TPU had the sort of properties that would make for a very light, durable, and ultra-compact bicycle inner tube, the kind of premium product that he, an enthusiast cyclist, would buy.

A typical butyl inner tube for a road bike weighs 100-110 grams. Tubolito’s lightest road bike inner tube weighs just over 30 grams. It’s also substantially more compact when folded, a space saver.

While many times more expensive than a standard inner tube, the compact, lightweight Tubolito tubes are rapidly finding acceptance with performance-obsessed road cyclists and pack-size-obsessed mountain bikers. A 29” MTB inner tube can weigh much more than 200 grams; the equivalent Tubolito MTB inner tube weighs just over 80 grams and is more compact, meaning more can be carried as spares, offering additional insurance against being stranded by flats.

Along with business partner Akos Kertesz, also from the world of acoustic membranes, Lembacher created Tubolito in 2015, spending a year to bring the product to market.

The company’s inner tubes, with valve stems sourced from Italy, are made in Austria using a patented seamless production technology. Most butyl and latex inner tubes are made in Asia.

Tubolito tubes are expensive, but, for many cyclists, money spent on reducing rotating weight is usually money well spent. Weight weenies often spend vast amounts on shaving grams from their bicycles.

“We see ourselves as tube engineers,” pointed out Kertesz on a telephone call from the Tubolito HQ in Vienna.

Stressing that the self-financed Tubolito aims to stay specific to the cycle industry, Kertesz added: “We believe this is just the beginning of our journey.”