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Friday, February 18, 2011

Bicycle tires – puncturing the myths [via Bike Radar]


By James Huang, tech editor, in Boulder, USA
Tucked inside a small industrial complex in Nastola, Finland is the nondescript grey building that's the base of independent third-party tire testers Wheel Energy.
Using a battery of purpose-built machines, founders Petri Hankiola, Veijo Pulkkanen and Marko Savolainen are addressing some of the common questions surrounding bicycle tires. They're coming up with some interesting answers that no longer have to rely on word of mouth, tradition or intuition for their veracity. 
Take these conclusions for example:
Puncture-resistant belts work but they're not created equal: Nylon, aramid and other belts placed under the tread do help ward off flats but there are benefits and trade-offs to the various materials. Tougher ones like aramid are durable and highly cut- and puncture-resistant but their stiff nature sucks up a lot of energy, contributing to rolling resistance. More flexible ones like nylon aren't as bulletproof but offer a better compromise if you still want to retain good performance.
Wider tires roll faster than narrower ones: Riders have argued for years that narrower tires – especially on the road – roll faster and are more efficient than wider ones when in fact, the opposite is true. According to Wheel Energy, the key to reducing rolling resistance is minimizing the energy lost to casing deformation, not minimizing how much tread is in contact with the ground. All other factors being equal, wider casings exhibit less 'bulge' as a percentage of their cross-section and also have a shorter section of deflected sidewall.

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