Broader wheels and tires are faster aerodynamically, plus much more snug to boot. S5 arrives specced with 28mm tires but has clearance for approximately a 34mm (measured) tire. Cervélo is amongst the iconic triathlon bike manufacturers, becoming a major-hitter during the triathlon Group for more than a couple decades now. https://cerveloroadbikes57890.ssnblog.com/26479759/cervelo-triathlon-bike-things-to-know-before-you-buy