What makes cycling tires fast?

• Posted by freeamfva jack May 14, 2021 - Filed in Arts & Culture - 699 views

  What makes a tire fast? We went to Nastola, Finland to find out. There, in the labs of Wheel Energy Oy — the best facility in the world for evaluating rolling resistance — we tested 34 tire models to separate the hype from the science.To get more news about mountain rims, you can visit zpebicycle.com official website.
  
  Pushing a road bike at 40 kilometers per hour on a flat road demands power output in the range of 270–350 watts for most cyclists. Wind resistance takes up most of that. But the second largest constituent of drag is rolling resistance. For example, two tires with a rolling resistance of 50 watts each will eat up 100 watts to hold a 40kph pace. No wonder you feel so slow on thick, tough, touring tires.What we found out: While supple and wider tires roll fast, tread compound is paramount. Like most cyclists, we assumed that a fine-thread, non-vulcanized casing (its thread is spiral-wrapped around a drum with only raw liquid latex brushed over it and no heat added) would offer the least rolling resistance. But only one of the top five tires in the test was a non-vulcanized open tubular. The other four were fully vulcanized tires (the entire tire is cooked in a mold, melting the rubber throughout all of the layers) with casings strung on a “calendar” (a big loom on which rubber is pressed into the fabric).
  
  So if you’re looking for a fast tire, don’t be afraid to go wide, and don’t have blind faith in conventional wisdom about compounds and tubes. The fastest tire in our test — the Specialized S-Works Turbo Tubeless Light — was vulcanized and full of sealant.
  
  It’s striking to see that four of the top five tires in our test come from Specialized. But the truth is that all five come from the same tire design team. The 25-millimeter Continental GP 4000S II — which, with its Black Chili tread compound, has been one of the world’s best-selling high-end clinchers for years—was created by the same engineers now running tire development for Specialized.Wheel Energy evaluates bike tires on a 1,200-millimeter-diameter drum with an interchangeable surface. To simulate an average asphalt road, they use a steel surface with a diamond-plate tread pattern like you might find on metal stairs
  
  The tires ranged in width from 22 to 26 millimeters and included standard clinchers, open tubulars, and tubeless versions. We tested them at 40kph with a load of 50 kilograms, each inflated to 116psi. To simulate the way we assumed most people will run these various models, we used 70-gram Bontrager XXX latex inner tubes in higher-end clinchers and 95-gram butyl tubes in less expensive ones. Tubeless tires took 25 grams of Bontrager TLR sealant.
  
  All standard clinchers were mounted to Mavic Ksyrium Super Light wheels, while tubeless tires went onto Fulcrum Racing 1 wheels.
  
  Wheel Energy has a rigorous calibration protocol that the company claims delivers an accuracy of ± 0.15 watts. This involves starting up the machine 12 hours before testing begins to bring the drum and room up to a standard temperature. Technicians then take three test measurements with three known tires to check for consistency. Finally, each tire runs for 10 minutes on the drum before any measurements are taken, to warm up, settle the tire shape, and work out internal stresses. The calibration procedure means the lab can test only two tires per hour.
  
  Though Wheel Energy has found that the difference between two tires of the same model is rarely more than 0.1 or 0.2 watts, we tested two tires for each model and averaged the results. So we spent one hour testing each model in our lineup.