Left and right pedals may be pushed independently of each other. Note the eccentric cams on the bottom bracket, giving the leg more force at the end of the stroke. A belt connects the pedal to the cam. A spring counter rotates the cam on the backstroke. Freewheel assemblies were used on each cam to lock on the power stroke and freewheel on the return stroke. Reciprocating motion works OK, but hurt my knees after a few rides around the neighborhood. Also note the wooden rack used for the boom, seat mounting, and hardware mounting. The wooden rack has some flex, but made it easy to attach components and make modifications. The Haro BMX frame was not drilled, cut, or otherwise modified. Seat is from Academy originally for bass boats. The original objective was front wheel drive, but my sore knees dampened my enthusiasm for this method.
This design was easy to try on the way to front wheel drive with a standard crank. Note the pipe nipple used for the bottom bracket assembly.
This design was copied from the Internet. The chain really does twist and stays on the sprockets during turns. (Back pedal and the chain comes off immediately.) Black wheels guiding the chain are plastic idler pulleys originally designed for belts.
Name: Mark Thomasson
Email: markthomasson at verizon dot net