Quick-Step add Rabon and Grabsch
Czech rider Rabon, 28, is a three-times national time trial champion and also won the Vuelta a Murcia last year, in addition to a handful of stages on other minor tours.
German veteran Grabsch (pictured), 36, has 16 career wins, including a World Championship title in 2008 and four national time trial wins.
"Frantisek and Bert are two excellent team players, athletes with great intellect who can win and carry their team mates into position to vie for victory," said team manager Patrick Lefevere.
"Both are fantastic cronomen and great pace setters who can carry out quality and quantity work at the front of the group."