Wider wheels and tires are faster aerodynamically, and a lot more comfortable in addition. S5 arrives specced with 28mm tires but has clearance for as much as a 34mm (calculated) tire. The Aspero is designed with gravel racers and go-fasts in your mind. Its aerodynamic tube styles borrowed from Cervelo's https://cervelo-tri-bike07395.thelateblog.com/27218502/the-2-minute-rule-for-bombay-bicycle-club