Debut: Michelin Square Bike Tube

Tire giant Michelin North America didn’t reinvent the wheel with its latest innovation. But the company may have reinvented the bike inner tube. If its square shape is not enough, than what about a design that is touted to be “twice as flat-resistant” as regular tubes?

The odd-looking Protek Max tubes, new this spring, are made square and with what look like blisters on three sides. The center line has large ovals and two sides have small circles, all of which disappear when the tube is inflated. The result is a tube Michelin cites as “900% more effective than self-healing tubes.”

Unlike traditional tubes that are stretched during inflation, the bumps on the Protek give the tube a compressive force that helps its excess rubber surround and self-seal a small puncture. Here’s how the company puts it: “Thanks to its uneven design, the Michelin Protek Max has a ‘compression’ reaction in the event of piercing or nipping (the hole closes up naturally) whereas a classic inner tube has an ‘extension’ reaction (balloon effect). The self-plugging effect is increased by adding the sealant at the origin.”

To put that another way, a traditional tube contains air until a puncture occurs and then the air-pressure helps force the air to escape. The Protek’s compression — think Ace bandage — and excess rubber double team the same sort of puncture to seal it. A small bit of tire sealant inside the tube offers additional protection.

Time to throw away that patch kit? Not necessarily. The only flat they don’t prevent is a pinch flat, according to the company.

The Protek tubes are a little heavier than traditional tubes and are designed for the more casual rider, not a racer counting grams. They come in two sizes, 700×35-47c and 26 × 1.4-2.125in, and with either Presta or Schrader valves.

Overall, these flat-resistant tubes are a great call for your around-town bike. At $8.99, the square tubes are just a smidge more than the average-priced traditional tube you’ve likely been using for years.

—Stephen Krcmar lives in Mammoth Lakes, Calif.