Steering

The steering system is similar to "go-kart" steering for simplicity, least maintenance, least weight and least cost. It consists of adapted bicycle front forks attached to "C" -shaped (more accurately "[" -shaped) steering knuckles that swivel on vertical bolts attached to a solid front axle. Steering arms that are ackermann-angled are attached to the inside of the front wheel hubs. A threaded adjustable rod connects the ends of the 2 steering arms and a second rod connects one of the steering arms to the steering yoke. A simple tube inside a support tube is connected to the yoke and, on the other end, to the bicycle handlebars. The support tube is supported by the pedal assembly and a hole through the firewall . The following pics give a visual summary. The major adaptations that were required to bicycle parts are emphasized.

The only feasible way to reuse bicycle front wheels was to use the entire fork which supports the wheel on both sides. The wheel axles are too thin (~9mm diameter) to support the weight of the vehicle when used in a conventional spindle or "protruding" way like most full size vehicles. The forks were reversed in order to provide a slight negative castor for easier steering. 

 The right front brake (LHS in pic) cable needed to be flipped to make the cable attachment inboard instead of outboard, The brake cable attachments were flipped vertically to enable easier cable routing, lower profile.

What NOT to try. 

I tried both these schemes. They do not work:

1. The usual approach to reusing bicycle steering is to mount the 2 forks by the stems on the firewall with a link to keep the wheels parallel as they are turned. This requires a positive castor like a bicycle, but results in more difficult steering when using larger wheels. An exaggerated example would be a custom Harley "chopper" with extended forks, but dangerous "flop" forces on the front wheel.  No relaxed driving allowed here!

2. The second from last scheme tried was to use the front ends of 2 bicycles (partial front frame + stem + fork + wheel) attached to either side of the firewall  with the forks extended and close to vertical. This resulted in progressive, uncorrectable toe-in or toe-out as the vehicle was moved back and forth!  Now that I did not expect! After much attempted tie rod adjustment and head scratching I decided to adopt the steering geometry that had the steering knuckles as close to the front wheel axles as feasible. This worked well, but required some welding effort. This scheme is the one illustrated.

The following photos show the adapted bicycle front forks. The inside ends of the forks were then welded to each "C" steering knuckle. For extra strength, 3 gussets were added to each knuckle where the fork end contacted the knuckle:

The following pic shows the bottom of the inside fork arm attached to the steering knuckle and steering arm. The steering arm has a hole at the end that accepts the wheel axle end and its nut secures both the steering arm and the wheel onto the inside fork.  For extra rigidity of the steering arm, the forward fender attachment hole is used to accept a small bolt through the steering arm end.

Steering is always a critical system of any vehicle and is detailed in Onshape here . (DWS: change link when done Onshape model).

Is there a crack in the longer weld? TEST more with braking!!  BEFORE YOU DRAFT IT!

Here are more detailed steps to build the steering system:

1.  Choose 2 front forks that are as similar as possible. If they are from identical bicycles, great! If not disassemble the front forks of all 3 bikes and compare the forks to determine the 2 best matches. For example, I used a flat surface and laid the forks side-by-side with bend facing down. I then measured from the top of bend to the flat surface. You may have to bend the forks slightly using a large vice if they are not within 1/4" of each other at the bend.

2. Bend or weld the steering knuckles specified here using 1/4" thick mild steel.