for lower-level injuries; although, some athletes with high-level disability use them as well. Manufacturers of this type of handcycle include Lighting Handcycles and Brike International Ltd. (Freedom Ryder). Another type of lean steer hand trike has two steering rear wheels and one non-steerable, powered front wheel with handholds offset at 180°, similar to pedal cranks, that can be operated with only one hand, thus making it easy to ride uphill, and it can be ridden in a tighter curve with the automatic rear wheels steering system. Off road The off-road is different from other handcycles in that there are two wheels in front and one behind, and it has a lower gear ratio range. This gives the cycle the ability to tackle steep slopes and permits handcycle mountain biking. The addition of a wider tire with suitable tread makes some mountain biking possible on standard road bikes. Touring Handcycles have also been used for touring, and to better accommodate this interest, some manufacturers incorporate mudguards and pannier cargo racks. As handcycles have evolved they have become progressively lighter, and they have better gearing for long climbs and long-distance touring. Racing Racing handcycles tend to be extremely low to the ground to minimize air drag and maximize the lateral acceleration that can be generated in a turn without rolling over to the outside. Wheelchair conversion An attachment, consisting of a steerable front wheel and crank, can convert a wheelchair into a handcycle. Gallery See also Bicycle Cycling at the Summer Paralympics Invalid carriage Para-cycling Outline of cycling Quadracycle (human-powered vehicle) Racerunning Recumbent bicycle Rowing cycle Tricycle References Mobility devices Human-powered vehicles