Downhill longboarding involves riding down hills as fast as possible and keeping the board under control. Speeds in excess of 80 mph have been obtained. UK rider, Pete Connolly, is the current Guinness world record holder, for the fastest man on a longboard, with a staggering top speed of 91.17 mph. These boards are usually long, with wheelbases of , and are very stiff to improve control at speed. "Speed wobbles" pose a problem for beginner downhill riders but intermediate and advanced users overcome this by learning to relax and control their muscles. Downhill decks usually fall into Six categories: top mount, micro drop, drop thru, drop deck, double drop and flush mount. Topmount boards provide the most traction but tend to be less forgiving. Micro Drops lower the ride height slightly, which results in a great all around board. Drop thru decks consist of mounting the baseplates of the trucks on top of the board with the trucks hanging through a hole. Like micro drops these tend to be all around boards and were very popular 2009–2011. Drop Decks get the rider very close to the ground, providing an easy to push and drifty ride. Double Drop decks are a drop deck with drop thru truck mounts. These decks were fairly popular in the mid 2000s but have largely fallen out of favor due to their unresponsiveness. Flush mounts seek to lower the ride height by mounting the trucks in a recessed area on the board. This minimally lowers ride height but increases the chance for wheel bite (which is where the wheels rub against the board in a turn, usually resulting in a crash). The vast majority of downhill longboards are built from wood. The three most common woods used are Maple, Baltic Birch and Bamboo. Maple is less prone to fracturing during construction than Baltic Birch, and as such is used in almost all high-end boards. Other materials used in longboard construction are: 1) Carbon fiber with a foam, balsa or hollow core. 2) Aluminum, either pressed or milled. And 3) Carbon Nano Tubes, although this proved prone to failure and no current company is using this material.