Replace your old 29"x2.1" bike tire with this great 29"x2.1" Black Hardpack CST1820 Bicycle Tire from Sunlite. Sunlite's tires are some of the most popular replacement bike parts on the market, and they are available in about every rim size in current use. Let Monster Scooter Parts be your source for the latest bicycle tires from Sunlite with this 29"x2.1" Black Hardpack CST1820 Bicycle Tire.