The roar of motorcycles was a common sound around the parish last week as the National Bikers Roundup, the largest camping motorcycle rally in the U.S., took over Lamar-Dixon Expo Center.Ascension Parish tourism officials expected 25,000 motorcycles from 1,00 motorcycle clubs from around the country in the parish for the five-day rally. Many of the bikers camped out at Lamar-Dixon in tents or motor homes or in other campsites around a four-parish area, said Tracy Browning, head of the Ascension Parish Tourism Commission, which worked with the national organization to bring the group to Gonzales.