Marji Gesick is a challenging mountain bike race held annually in Ishpeming, Michigan. The race is known as the hardest single-day mountain bike race in the US, with a mantra of "Find your limits and destroy them." It offers both a 100-mile and a 50-mile (approximately 100k) course, with the 50-mile version featuring about 8,000 feet of climbing and being around 80% single track, 10% two-track, and some paved bike trails or roads. The race is so difficult that about 25% of the 50-mile entrants and almost 50% of the 100-mile entrants do not finish.