Bumpy Bike Tubes Reseal Punctures
You’re riding along on your favorite mountain biking trail when you hit a rock that’s a little too sharp and your front tire is losing air. If you happen to have the Michelin Portek on there, you might be able to ride back to civilization rather than carry your bicycle over your shoulder for the long trip home.
The idea of a self-sealing inner tube isn’t exactly new. We see them on a range of car tires, as well as tires for bicycles. However, the inner tube on the Michelin Portek is quite different. First, it has a square cross-section rather than a round one. This is supposed to provide for a better fit against the rim and it eliminates that “twisting” problem you get when mounting.
Perhaps more importantly, the surface of the Portek has a series of bumps on it. When you inflate a regular inner tube, it expands the rubber on the outside. This makes small punctures even bigger. The bumps on the Portek, on the other hand, get the rubber to compress rather than expand. This helps to make small punctures even smaller. This way, that sealing goop can more easily do its job.
We’ll have to wait for some impartial third parties to give the Portek a try, but it sounds promising. Each tire sells for $8.99 and they’re offering them for commuter and mountain bikes for now. Road racers will have to wait.