Tratnik started cycling at the age of 17 on the advice of Borut Božič who noticed him during a mountain bike competition organized by his school. He found success in races during his second season as a junior in 2008, winning the national junior time trial championship and the Coppa Linari.[8]
Under-23 years (2009–2012)
Moving up to the under-23 category, he was recruited by UCI Continental teamRadenska–KD Financial Point, which he rode the 2009 and 2010 seasons for. With the team, he had his first victory at the under-23 level, winning the 2010 Gran Premio della Liberazione. He also finished second overall in the Giro delle Regioni, an event on the UCI Under 23 Nations' Cup calendar, and competed at the under-23 world championships both years. At the world championships, Tratnik placed 60th in the road race and 52nd in the time trial in 2009, and did not finish the road race in 2010.[9]
The following season, Tratnik made the step up to the UCI World Tour with Quick-Step. However, he was let go at the end of the season after a lack of results, largely due to an eating disorder causing him to lose an unhealthy amount of weight, forcing him to rejoin Radenska in 2012.[10] That season, he won the European under-23 road race championships in his final year as an under-23 rider.[11]
Continental teams (2013–2016)
For the 2013 season, Tratnik again moved teams, this time to Austrian Continental squad Tirol Cycling Team. He once again struggled to find form and was involved in several crashes throughout the year.[12]
In 2014, he transferred again, to another Austrian Continental team, Amplatz–BMC, on a three-year contract. Here he found success at a number of Continental Tour level events. In 2015, he won the Grand Prix Südkärnten, the second stage and the general classification of the East Bohemia Tour as well as the fifth stage and the points classification of the Tour de Hongrie. He also finished third in the fourth stage of the Tour of Austria and won the points classification. That same year, he won the elite national time trial championships and placed fourth in the road race. In 2016, his success continued, winning the elite national road race championship and the overall classification of the East Bohemia Tour.
Bahrain–Merida: Return to the World Tour (2019–2022)
In 2019 Tratnik returned to the UCI World Tour after a seven year absence with his signing to Bahrain–Merida. In his first season with the team, Tratnik took his first ever World Tour victory, the prologue of the Tour de Romandie, and competed in his first Tour de France. The following March, Tratnik nearly won a stage of Paris–Nice but was caught with 200 meters remaining.[17] However, in October, he took his biggest win in his career yet, winning stage 16 of the Giro d'Italia, six seconds ahead of Ben O'Connor.[18]
In 2023, Tratnik moved to Team Jumbo–Visma. He was slated to ride the 2023 Giro d'Italia in support of Primož Roglič. However, the day before the race, he was hit by a car while doing recon for the time trial, breaking his kneecap in the process. He was able to return to training four weeks later, and competed in the Vuelta a España.[10]
Tratnik started the 2024 season strong, taking his biggest one-day race victory yet: the Omloop Het Nieuwsblad in a two-man sprint against Nils Politt.[7]
^"Syuk - Jan Tranik". Syuk is Jan's nickname which he got after his older brother, who was a basketball player.
^ abGadzała, Paweł (12 November 2017). "CCC Sprandi Polkowice signs Szymon Sajnok". Cyclingnews.com. Immediate Media Company. Retrieved 7 January 2018. With two newly-signed rouleurs – Paweł Bernas (Domin Sport) and Kamil Gradek (ONE Pro Cycling) – the team is expected to focus more on flatter stages and one-day races and play cards of Jan Tratnik, Jonas Koch, Frantisek Sisr or Alan Banaszek.