250 career
- Rockstar Husqvarna
Mosiman made his professional debut in the 2017 AMA National Motocross Championship, as part of the Rockstar Energy Husqvarna Factory Racing team. [4] He adjusted well to the 250 class, finishing eighth overall at the second round. Mosiman picked up a shoulder injury at the fourth round and missed the rest of the championship. [5] He made his professional supercross debut in the 250SX East class of the 2018 AMA Supercross Championship, but missed the first two rounds due to concussion. [6] Across the rounds he raced, he had a best finish of eighth and ended fifteenth in the standings. Mosiman finished eleventh in the 2018 AMA National Motocross Championship, becoming a more regular feature in the top-ten during the second half of the season.
Mosiman took a step forward in the 2019 AMA Supercross Championship, with a best finish of fourth alongside six other top-ten finishes, he finished sixth in the final standings of the 250SX West class. His progress continued in the 2019 AMA National Motocross Championship, picking up his first podium at the third round at Thunder Valley. [7] After two more top-three race finishes and a number of top-fives, Mosiman finished the series in eighth overall. Mosiman continued picking up maiden podiums during the COVID-19 pandemic-hit 2020 AMA Supercross Championship, finishing third at the fourth and final rounds, to end the season fifth in 250SX West. [8] A practice crash following the conclusion of the supercross season, saw Mosiman miss the entire 2020 AMA National Motocross Championship. [9]
- Troy Lee Designs Red Bull Gas Gas
For the 2021 season, Mosiman moved from the Rockstar Husqvarna team, to join the first factory Gas Gas squad in America. [10] Racing in the 250SX East class, Mosiman secured two more podiums and as in the previous supercross season, finished fifth in his class standings. During the outdoor season, he matched his podium count of the previous season, finishing second overall at the sixth and eleventh rounds. He would miss the eighth and ninth rounds due to injuries sustained in a practice crash and would finish the championship in eighth. [11] Mosiman competed in the 250SX West class of the 2022 AMA Supercross Championship, taking his first win at the third round of the championship in San Diego, where he led every lap of the main event. [12] Throughout the rest of the season, Mosiman stood on the podium four more times, before finishing the championship in third in the final standings. His first supercross win was followed by his first outdoor race win, when he was victorious in the opening race at the second round of the 2022 AMA National Motocross Championship. [13] A crash in the second race ended his chances of the overall win and a tough second half of the season, where he missed multiple rounds due to injury, saw him end ninth in the standings.
After recovering from a broken neck sustained at the penultimate outdoor round in 2022, Mosiman competed in the 250SX East class of the 2023 AMA Supercross Championship. At the fourth round at Daytona, Mosiman crashed out and sustained a head injury that ruled him out for the rest of the supercross campaign. [14] Returning for the 2023 AMA National Motocross Championship, crashed out of the second round, picking up a shoulder injury that ruled him out of the rest of the season due to required surgery.
- Monster Energy Star Racing Yamaha
Whilst initially left without a deal for the 2024 season, Mosiman eventually signed for Monster Energy Star Racing Yamaha on a multi-year deal. [15] After only riding two rounds of the 2024 AMA Supercross Championship, Mosiman hoped to compete in the full 2024 AMA National Motocross Championship season. However, a crash prior to the opening round resulted in fractures in his neck. With the severity of the injury, Mosiman considered his future in the sport, organising a retirement party to seemingly call time on his career.
After being told by doctors that there was no further risk of injury once the neck fractures had healed, Mosiman surprised many by lining up in the 250SX West class of the 2025 AMA Supercross Championship. In what was a comeback season after two years dogged by injuries, Mosiman scored a podium at the fifth round in Arlington, Texas, finishing seventh in the final standings. He also scored a single podium in the 2025 AMA National Motocross Championship, but missed the final round due to injuries and a concussion sustained in a crash at the penultimate event. [16]
