Tuft recorded a time of 20 minutes 25 seconds on the 17.4km course, five seconds quicker than second placed American rider Taylor Phinney, while Dutch rider Lars Boom was a second further back in third place.
Alberto Contador, riding in his first race back from a doping ban, was sixth fastest.
Tuft's victory saw him overtake overnight leader Tom Boonen at the top of the general classification, leading Boom by four seconds and Sylvain Chavanel by 16 seconds.
At the final stage of the Tour de l'Ain in France, Thibault Pinot produced a stunning breakaway victory to beat Romain Bardet by 43 seconds, with the remained of the field a further one minute seven seconds distant.
Andrew Talansky finished in the pack to complete his overall victory, 12 seconds ahead of Sergio Pardilla Bellon.
In Italy, Colombia's Esteban Chaves won the 63rd Gran Premio Città di Camaiore.