There are three main parts to the trike: the front power wheel (Steps 1-4), the main frame with seat (Steps 5-6), the rear steering wheels (Steps 7-11), rigging (12) and the optional cargo rack (13). The trike is built from parts from three donor bikes I got at a bike coop as I described in this "Ible": https://www.instructables.com/id/How-I-Get-Free-Bike-Parts-Legally/ A parts list is on its way (14).
Welding is required and the cost for purchased parts was roughly $100.
Front wheel 24"
Rear wheels 20"
Width of track 31"
Length overall 78"
Step 1: Front Wheel Drive
Front wheel drive has some advantages and some disadvantages. I like it because it is simpler than a rear wheel drive delta trike (no differential is required) and there is not a long chain run.
The two main disadvantages are that it loses traction going up hills because most of your weight is to the rear of the trike and that you probably will want to steer with the rear wheels.
Step 2: Harvest a Rear Fork With Pedals
Start thinking of the old right side of the rear-facing fork as the new left side of the front-facing fork.
Cut off the top tube and bottom tube right next to the bottom bracket shell.
Step 3: Invert the Derailleur
Step 4: Weld Main Frame to Bottom Bracket Shell
Step 5: The Main Frame
The completed lower part of the frame is 40" long. At the rear the main tube makes a right angle turn upward (Photo #4) and then is 23" tall. The upright tube is double for about half its height (Photo #5).
Step 6: Seating
Photo #3 shows the location of the seat attachment. Up close (Photo #4) you can see that both seats were attached to 1" angle iron pieces welded to the main frame of the trike. The two pieces of angle iron that are at right angle to the main frame tubes were for the first cushy seat. The two pieces of angle iron that are joined and run along the long axis of the main frame were for the second lighter seat. You don't need both attachments - choose one way or the other.
Photo #5 shows the underside of the new seat. There are two pieces of 1" angle iron welded to half of a rotating seat mount. I drilled out the center rivet of the seat mount and separated the two black metal plates. I spaced the angle iron mounts so they fit along the outside of the angle iron pieces welded to the main frame and welded them to the black metal plate. Then I drilled three 1/4" holes through all four angle iron pieces to hold the seat to the frame (Photo #6 and #7).
Step 7: Harvest Two Matching Front Frames
The two front forks need to match too. You can swap matching front forks in place of unmatched ones if needed (Photo #5).
I refer to these two side frames as "wings".
Step 8: Weld Wings to Main Frame
The two head tubes should be exactly vertical and thus parallel with each other. The two "wings" (side frames) on each side of the main vertical tube should be in line with each other. When everything is true and square weld it solidly together.
Step 9: Weld Steering Arms to Forks
Step 10: Add Steering Linkage
A 2" long 3/8" hex head bolt is welded at right angles to the carriage bolt and is bolted through a 3/8" hold in the end of the steering arm with two more nuts (Photo #4).
Step 11: Add Tillers
The tillers move in tandem because the two forks are linked together by the steering linkage. Moving the tillers to the left turns the trike to the right (and vice versa) just like a tiller on a sailboat. This will seem strange at first but soon becomes second nature.
Step 12: Rigging
I have brakes only on the front wheel. The cable from the brake (Photo #3) loops back under the seat and up to the right tiller (this should probably be on the left tiller to be standard) (Photo #4). I have an inner tube tie around the brake lever to act as a parking brake in this Photo.
Rear brakes will eventually be added, but they need to be synchronized on both rear wheels or they will pull the bike as it stops.
Step 13: Cargo Carrier
A piece of 3/4" EMT conduit is welded to the top of another piece of 3/4" EMT which slides down into the seat tube over the front wheel (Photo #2) and is bolted in place.
A second piece of 3/4" EMT extends is welded to two 1/2" EMT supports that extend down on each side of the front wheel stays. "J" hooks are used to secure these supports to the seat stays and chain stays (Photo #3, #4 and #5).
Please see my "Ible" on some safety tips for welding EMT if you are not familiar with the safety concerns: https://www.instructables.com/id/Welding-EMT-Conduit/