Common year starting on Friday has only one Friday the 13th; The only Friday the 13th in this common year occurs in August. Leap years starting on Thursday share this characteristic, but also have another one in February. This is the only year type where the "n"th "Doomsday" (this year Sunday) is not in ISO week "n"; it is in ISO week "n"-1. In the (currently used) Gregorian calendar, the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-three common years per cycle or exactly 10.75% start on a Friday. The 28-year sub-cycle does only span across century
Friday the 13th motorcycle rally Friday the 13th motorcycle rally The Friday the 13th Motorcycle Rally is a motorcycle rally held every Friday the 13th in Port Dover, Ontario, Canada since 1981. Its typical summer attendance exceeds 100,000 bikers. The event has been described as "the biggest single-day motorcycle event in the world," a title also claimed by the Rolling Thunder rally in the United States. Although hundreds of attendees arrive during winter months, attendance is at its highest when the date falls on a summer day. In August 2010, the rally drew more than 150,000 attendees. Estimates for the July 2012 event ranged from