A bicycle that can be pedalled with hands and feet at the same time has been developed by Dutch studio TSG Essempio.
Pedals replacing the handlebars allow the 4StrikeBike to be cycled with the hands and steered simultaneously.
These pedals click into a fixed upright position so the bike can also be used normally.
"The 4StrikeBike has adjustable pedalling handlebars and can be used as an ordinary city bike in traffic as well as a touring bike for longer distances at higher speeds," Jan Willem Zuyderduyn of TSG Essempio told Dezeen.
A chain runs up one side of the frame between the hand pedals and the standard mechanism linking the foot pedals to the back wheel.
The crankshaft has a special freewheel system that allows the bike to be cycled with both the upper and lower body, or just the legs while getting on and off.
Retired Dutch surgeon Lex van Stekelenburg came up with the idea for the bike after developing back problems, following years of performing lengthy operations while standing with a hunched posture.
Van Stekelenburg took the concept to TSG Essempio, who developed his proposal and prototypes further.
We've featured a number of unusual bicycles, including one made from see-through plastic and another constructed out of cardboard. See more cycling design »