A recumbent bike with a very comfy seat.
It's a 35 pound leather executive office chair connected to a 16" (little girl's) Princess bike re-welded into a recumbent (recliner bike) and using a piece of another donor bike frame.
I built it in honor of "Bike to Work Day".
If you like fun/unusual home built bikes... check out my hobby site Woodenbikes.com
Step 1: Design your bike using a CAD system (Cardboard Aided Design)
Make a cardboard cutout of your lower leg (with foot and pedal), thigh, torso, and straight arm (to a distance 2" back from your wrist). Use it to look for good riding position and clearances for knees to bars, heels to wheels etc. Use the CAD system to layout the riding position, cranks, wheels etc with attention for locating your hands, shoulder, seatback angle, butt, knees and feet. Also look for ways to arrange a straight chain line (at least for the tight side) by raising the Bottom Bracket (BB)(main crank bearing).
For detailed instruction on designing a sweet handling recumbent visit www.bikesmithdesign.com
Step 2: Cut and Miter the bike tubes for joints
Use a hole saw (toothed cylindrical drill bit) to simultaneously cut and miter the donor bike's former downtube to become a boom tube out to the Donor bike's BB. Carefully eyeball the angle but always wear eye protection when eyeballing.
Step 3: Clamp or strap tubes together for welding
During and after filing the donor tube's mitered end, the joint is assembled and checked for correct angle, centeredness (meditation could help here) and plumbness (allignment by eyeball). When it all looks straightish, it is clamped or straped together to be tack welded.
Tack welds are small to avoid melting too much of the nylon strap.
Step 4: Weld it together
I use a little 110 volt MIG* welder. It is the red box. The weld is finished in this picture.
*MIG = Metal, Inert Gas sheilded welding. however I use a cheaper flux cored feed wire instead of gas sheilding. It helps keep my weld quality low so I won't obsess as much.