De Backer has signed up for another three seasons, while Curvers will be with the team for at least another two. Hupond has renewed until the end of 2015, while Timmer's new contract will keep him with the team until the end of 2016.
"All four have developed well again this year within the team and are stronger than ever," Team Giant-Shimano coach Rudi Kemna said on the team's official website.
"Roy is a really important rider in the team as one of our captains and in this he plays a key role in the results of others. Bert is also still developing and is a key rider in the classics as well as being experienced in preparing the sprints. As a captain in these races he makes a real difference.
"Albert and Thierry also both showed they are still progressing with strong results this season. Like with Roy and Bert, we don't just look to their results, but at the role these riders have in the team and the impact they have in races. I am happy that we can continue to move forward with these riders."