A bicyclist was killed Saturday at Walnut Creek Park. Albemarle Police say the victim was 50-year-old John R. Potter of Charlottesville. It happened just after 2:30 p.m. at Walnut Creek Park off Old Lynchburg Road in the southern part of the county. Police say Potter was riding a mountain bike with a friend on a trail. Police say it appears Potter fell off the bike and hit a rock. Police say Potter and his friend were both wearing helmets and were experienced mountain bikers.