Bicycle tire tubes need to stay firmly inflated against the inner surface of the tires themselves to ensure safe, rugged riding. But in the unlucky event of a puncture, that same pressure will only stretch the hole wider — even when it’s closed with sealant. Michelin’s new line of ProTek Max inner tubes employ a radical design to avoid this problem: The air pressure inside actually compresses a puncture closed, instead of blowing it further open.
The reason for this design problem is easy to visualize for anyone who’s ever had a hole in their sock. The simple fact of shoving your foot into the frayed heel and stretching the fabric will only make the hole bigger. Air pressure and friction in a punctured bike tube cause the same problem. But the funny-looking compression dimples on the ProTek Max’s surface change the distribution of pressure across the tube’s surface, cause the inner air pressure to squeeze a hole shut.
That’s ingenious enough, but the ProTek Max also addresses the plain fact that changing an inner tube at all, for any reason (even to install a ProTek!) is a giant pain in the butt. Traditional tubes with circular cross sections easily get twisted up when you’re trying to place them correctly inside the empty rim. But ProTek Max tubes have a square cross section — so properly mounting them into a rim is as simple as lining up the edges.