What does the HD stand for? Heavy Duty. Sunlite's Gold Tec HD Rack is made for the hardcore commuters and tourers out there that load up and ride more than most people drive. Made from lightweight tubular aluminum, the HD Rack is durable enough for daily commutes, tough enough for cross-country trips and doesn't weight you down. The top deck has a capacity of up to 55 pounds and side struts support fully loaded panniers. Plus, it fits both road and mountain bikes.