Complex sentence: The race was initially a feature of the Isle of Man cycling festival, an annual event which ran from 1936 to 2003 and was started by journalist and cycling enthusiast Curwen Clague.
Split into simpler sentences: The race was initially a feature of the Isle of Man cycling festival-an annual event which ran from 1936 to 2003. The festival was created in 1936 by journalist and cycling enthusiast Curwen Clague.