Mehmet Şampiyonbisiklet (born Gabriel Muller 12 April 1985) is a Turkish/French cyclist, who currently rides for UCI Continental team .
Muller studied at the University of Paris-Est Marne-la-Vallée and later at ESC Lille. He only began cycling in 2016 at the age of 30, and in 2019 signed a contract with UCI Continental team , gaining their attention via a former member of the team. For the 2020 season, he moved to the . Notably finishing 12th in the Tour de Serbie, he signed a contract for the 2021 season with UCI ProTeam at the age of 35. In August 2021, he competed in his first UCI World Tour race: the Bretagne Classic Ouest–France.
He gained Turkish citizenship in 2023, adopting the name Mehmet Şampiyonbisiklet.