Martens started racing junior level events in 2000 showing no particular specialization finishing in the middle of the pack in the Niedersachsen Juniors and Cottbuser Juniors races. In 2001 he started to show some form finishing 3rd in Stage 1 of the Trofeo Karlsberg beating the chasing peloton by 2 seconds.[6] Later in the year he finished 10th overall at the Münsterland Tour Juniors, a race he would win the senior version of later in his career. In 2002 he rode the Jadranska Magistrala finishing 56th overall with his best result coming in the stage 3 sprint where he finished 16th. In late May 2002 he rode the Tour de Berlin where he finished 13th overall but was the first rider born in 1983 or later so he won the young rider classification.
He started 2003 with a win in the Rund um Sebnitz in Germany, and he also took a podium placing on Stage 1 of the Tour de Berlin. 2004 saw Martens finish second at the under-23 German National Time Trial Championships, and finished 13th in both the European and World under-23 time trials later in the season.[7][8] Martens signed for amateur team KED Bianchi Team Berlin for the 2005 season, this gave him a calendar with more UCI races over the year. He started the year with a win at the Harzrundfahrt national event,[9] followed by 5th in the Stage 1 sprint of Circuit des Ardennes and a win at the Under-23 German National Time Trial Championships.[9] For the later part of the 2005 season he was a stagiaire at UCI ProTeamT-Mobile Team.[10]
Skil–Shimano (2006–2007)
In November 2005 Skil–Shimano announced they had signed Martens to their team on a two-year contract.[9]
2006
Martens' professional career began in Qatar with the International Grand Prix Doha where he finished in second-to-last position, nearly 4' 30" down on the winner. Having acted as a domestique in his next starts in stage races, Martens moved onto the Cobbled classics and Ardennes classics.[11] Martens contested, for the only time in his career, the Tour of Flanders and Paris–Roubaix, finishing just the latter and at almost 20 minutes down in 99th position.[12] He recorded two top-10 stage finishes at April's Rheinland-Pfalz Rundfahrt, followed by a top 10 in Stage 4 of Tour de Picardie the following month. The Tour de Luxembourg brought Martens' first professional win, winning Stage 3 ahead of eventual overall winner Christian Vande Velde.[13] Martens' second professional win came at the Münsterland Giro where he took the early breakaway and held the peloton off by two seconds.[14]
2007
Martens started 2007 at the Vuelta a Andalucía where he finished 6th in the bunch sprint of stage 2 and ended 21st overall after the 5 stages.[15][16] He failed to finish at Omloop Het Volk and the Nokere Koerse, but finished third at the Grand Prix Rudy Dhaenens. The first top-10 result in a stage race came at the final edition of Rheinland-Pfalz Rundfahrt where Martens finished 4th in Stage 3 and then 2nd in Stage 4 to finish 5th overall, 16 seconds down on the winner. At the Tour de Luxembourg in June, Martens finished in the top-10 in 3 stages and ultimately finished 4th overall, 25 seconds down on the winner.[17] Stage 3 of the Ster Elektrotoer was won by Martens from a reduced bunch sprint after a hilly battle on the Cauberg,[18] which earned him the race leader's jersey; he lost the race lead to Sebastian Langeveld on the final day and finished second overall.[19] In August he raced the Rund um die Hainleite where he came third in another reduced bunch sprint.[20] His last major result came at the Eneco Tour where he finished 9th overall.
Rabobank (2008–2021)
In October 2007, Martens announced he would ride for UCI ProTeamRabobank from 2008 on an initial two-year contract, saying his three professional wins in two years at Skil–Shimano were impressive.[21]
2008–2009
Martens at the 2008 Sachsen Tour, where he finished in eighth overall
On his first race day of the 2013 season, Martens won the opening stage of the Volta ao Algarve into Albufeira; he and Tiago Machado had gone clear of the field within the closing stages, and they managed to remain clear while teammate Theo Bos led home the peloton in third place, a few metres behind.[32] Later in the spring, he finished third in the Volta Limburg Classic in a sprint finish of a select group of riders.[33] In June, Martens took his first overall stage race success,[34] by winning the general classification at the Tour de Luxembourg; he was third overall heading into final stage,[35] but was able to overhaul Jonathan Hivert and Matthias Brändle on the hilly finishing circuit in Luxembourg City, and took the overall victory by four seconds ahead of Hivert.[36] He later took top-ten overall finishes at the Tour de Wallonie (ninth) and the Arctic Race of Norway (fifth).[37][38]
In February 2020, Martens announced that he would retire from cycling at the end of the season; however, due to the COVID-19 pandemic, Martens intended to prolong his career until the middle of the 2021 season.[44][45] He retired following the 2021 Giro d'Italia,[4] where he finished 99th.
