John Crellin, 55, of Douglas, Isle of Man, was involved in an accident at the Mountain Box portion of the course on his fifth lap in the Senior TT.
Crellin was an experienced Isle of Man TT competitor and raced in the Manx Grand Prix in the early í80s. Earlier in the day, Crellin earned his first Isle of Man TT podium with a third-place finish in the inaugural TTXGP clean emissions motorcycle race.
A civil engineer with the Isle of Manís Department of Transport, Crellin was also an avid mountain climber, scaling some of the highest mountains in the world. In May, Crellin returned to the Isle after his third attempt at climbing Mount Everest, cut short by a stomach illness.
Previously, Crellin climbed Mount Elbrus in 2000, Kilimanjaro and McKinley in 2001, Vinson Massif in 2002, Carstensz Pyramid and Kosciuszoko in 2006 and Aconcagua in 1998, 2008 and 2009.