With the 21-inch front and 18-inch rear tires, Africa Twin seat heights soar from 33.5 to 34.3 inches. On top of the bike’s 507-pound curb weight, this begs a big, strong rider. The Adventure Sports model ups fuel capacity 28 percent to 6.4 gallons, wheel travel increases nearly an inch, the seat climbs further to 35.4 to 36.2 inches, and claimed curb weight jumps to 533 pounds. We’re talking big, folks. A dual-clutch transmission is optional on both models.