The Sisters' Centennial Motorcycle Ride honored the exploits of Augusta and Adeline Van Buren, who in 1916 rode motorcycles more than 5,000 miles (8,000 km) across the country to prove that women could be military motorcycle couriers, able to endure long distances and harsh conditions as well as men. "For me, part of riding motorcycles still is the challenge of embracing the unknown, the mastery of machine and also facing my fears and meeting the challenges of an extended motorcycle adventure," said Clickenger, whose company focuses solely on tours for female motorcyclists. Manufacturers such as Harley-Davidson produce entry-level motorcycles but it can still seem "intimidating getting on a powerful vehicle," said Pam Kermisch, a novice rider who works for Polaris, the company that owns Indian and Victory motorcycle brands. The bottom line is it's about empowerment, and the feeling of freedom — freedom from our fears, freedom from societal constraints, freedom from our own self-constructed, pre-conceived constraints and breaking those boundaries. [...] that's the ulterior motive to her venture. Diane Huston, who served in the Middle East during a 20-year career in the Air Force, is long past the learning stage, and she wasn't deterred after the first ride on her new Harley-Davidson in 1995 ended up in a swimming pool. "To me, riding a motorcycle is an absolute brain dump with the freedom of wide-open spaces," said Huston, who was on the centennial ride, toured Cuba, and hopes to go on Clickenger's Africa tour next year.