The line to the men's room at Nimrod Restaurant is peculiar because it usually contains both men and women. Near the restroom's doorway, gatherers careen and crane their necks to see a 200-year-old hole and the projectile that created it: a cannonball from the War of 1812. This hands-on history lesson is one of many elucidated by the guides at Phat Tire Bike Tours. They backdrop their classroom against the scenic sights of crashing waves, lush gardens, and bustling downtown shops. Seated on personal bikes or rental bikes that correctly answer the question, "What's my favorite color?", groups can set out on tours of places such as Falmouth, Plymouth, Martha's Vineyard, or Nantucket.