Autumn 100

The Autumn 100 is run from the twinned villages of Goring and Streatley on the River Thames, and its course is four separate 25-mile out-and-back spurs from the same start: two on the Thames Path, to Little Wittenham and to Reading, and two on the Ridgeway, to Swyncombe Farm and to Chain Hill. Centurion Running calls it the fastest trail 100 in the UK, at 100 miles with 5,000 feet of climb and 16 aid stations.

It starts at 9:00 a.m. and holds a 28-hour cutoff, which puts up to 13 hours of darkness in the middle of the race. Entry is first come, first served and needs a 50-mile finish inside 15 hours. It is the last leg of Centurion's Grand Slam of 100s, won by finishing it in the same calendar year as the Thames Path 100, the South Downs Way 100 and the North Downs Way 100.

Four separate 25-mile out-and-back spurs from Goring and Streatley, run in order: Little Wittenham on the Thames Path, Swyncombe Farm on the Ridgeway, Chain Hill on the Ridgeway, and Reading on the Thames Path. The shape of the four together is a cross. 100 miles with 5,000 feet of climb, 16 aid stations, 20 percent road and 80 percent trail, a 9:00 a.m. start and a 28-hour cutoff.

Entry is first come, first served through Centurion Running, with a waiting list once the 250 places are gone. It requires a 50-mile finish inside 15 hours, checked six weeks before race day, and volunteers who give over 10 hours of service to the race earn a guaranteed place the following year. Runners can also enter as part of Centurion's Grand Slam of 100s, which is 50 places and covers all four of its 100-mile races.