The team announced that Ethiopian Tsgabu Grmay and Italian Nicola Conci will join the squad from 2018, leaving Bauke Mollema as Trek's leading Grand Tour contender.
Mollema finished seventh in this year's Giro d'Italia, and 17th in the Tour de France with a win on stage 15. The Dutchman's best overall Grand Tour placing so far in his career has been fourth in the 2011 Vuelta a España.
Other riders in the team could now step up to lead in Grand Tours, such as 28-year-old Colombian Jarlinson Pantano, who posted top 20 finishes at the Tour de France in 2015 and 2016 and has been a key helper for Contador during 2017.
Contador retired after completing this year's Vuelta a España, where he finished in fifth place overall behind winner Chris Froome (Team Sky). Contador put in a trademark daring ride to net stage 20 on Alto de l'Angliru, closing out a career that has seen him win two editions of the Tour, two of the Giro and three of the Vuelta.
Trek general manager Luca Guercilena told Cycling Weekly in August that the team was not going to rush into replacing Contador, saying: "We are going to assess the opportunities when they come. We are not going to go crazy because we have to replace Alberto at all costs."
Along with Grmay and Conci, Trek has signed Gianluca Brambilla (from Quick-Step Floors), Alex Frame (from JLT Condor), Toms Skujiņš (from Cannondale-Drapac) and Ryan Mullen (from Cannondale-Drapac) for 2018.
German John Degenkolb and Belgian Jasper Stuyven are likely to spearhead Trek's assault in the Classics.
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