Steering has been a moving target (🥁). I had some early success with the control arms attached the the front wheel, but the human controls proved to be challenging.
Handlebars had seemed to be the simplest solution for turning the Falcon. My knees would clear the handlebars while pedaling and the brake and shifters would have a natural mounting location. However, the range of motion of the steering arm, at greater than ±90°, was too large to use handlebars. They didn't run into my knees, but they did poke me in the ribs. This was not a workable solution.
Handlebars were actually my second idea. I went back to the original idea of using a steering wheel. I had previously bought a go-cart racing wheel last year that had a very flight-oriented look and also had a spot for mounting a handbrake. It would easily handle the range of motion, but this scheme needed a new place to mount the gear shifters. Since I already had to make an adapter to attach the steering wheel to the steering column, why not also use that to also mount shifters?
I designed a simple adapter with a hole pattern for the steering wheel on one end and a square hole to lock onto the steering column at the other end. Most of the inside was removed to reduce weight. I carved a "saddle" into the neck of the adapter to match the profile of the original handlebar neck.
I then mounted the handlebars on the adapter and the shifters onto the handlebars. This placed the shifters close to my fingers (similar to car paddle shifters).
Using a steering wheel also required re-routing and re-supporting the steering column. Originally, it ran underneath the bike frame and connected directly to the steering arm. To get the steering wheel better aligned, I had to go up and over the bike frame. I secured the steering column using two haim joints. Haim joints are eye bolts with self-aligning eyes. They are mounted to the bike frame on threaded rods so the steering wheel location can be adjusted when needed.
The front wheels turn by tugging on a long arm attached to the left wheel, called a Pitman arm. It's attached to a steering arm that pushes or pulls on the Pitman arm when it turns.
Having the steering arm swing under the pedals was problematic. A mating bolt stuck out too much and intermittently impeded the pedals. This would definitely be a problem in the race, so I rotated the steering arm 180 degrees to avoid pedal interference altogether. But this created a different problem.
Turning in the right direction
Rotating the steering arm 180 degrees caused the tires to be out of phase with the steering wheel. Steering left now turned the tires to the right! And steering right turned them left. 🤦🏽♂️ I tried for many days to find an in-phase spot for the steering arm, but the new location was the only way to get the full turning radius of the tires. I finally came around to it. I needed gears.
Instead of attaching the steering column directly to the steering arm, I would connect them using gears. The steering column would turn a gear that drove the mating gear attached to the steering arm. It sounds complicated but a picture is easier to understand.
The gears needed to sit parallel to each other at a specific distance. This required yet another mounting plate and a new steering arm. I designed the mounting plate in Fusion 360, wrote the machining program to make it, and carved the part out on Lowell Makes' Tormach CNC mill.
I made the three pieces that make up the new steering arm, mostly on the lathe and mill but also with a drill and hole saw. Then I welded those pieces together.
After installing the steering upgrades, I discovered another wobble that I did not anticipate. Instead of turning the tires, the steering column dances like a tree in strong wind. We need all the turning energy to get all the way to the tires.
I figured out that problem. There is a long shaft on either side of the universal joints. The top one is secured at two locations, but the bottom one is only secured at one. I needed to also hold the shaft higher up, but there was no easy place to mount this new support.
I decided to create a tall bracket to hold the shaft in place and secure it with the same bolts holding the gear platform in place. The bracket was made up of three pieces, welded together.
I used the existing plate and gears to align the support bracket, then finished welding it together.
Once I finished the tall bracket, I installed it on the Falcon. I think my designs are looking a lot more Star Wars!
Shifting into gear
The last thing we needed for the Falcon to move was to wire the derailleur shifter and attach the bike chain. I mounted the shifter and ran the cable to the derailleur under the seat.
The bike cassette is mounted slightly forward from the usual location. My first attempt at support brackets worked for a while, but aligning the brackets to each other was very difficult and eventually jammed up the axle.
I realized I only needed to support one side of the cassette because the other side was already supported by the Hyperdrive frame. By using only one support, we avoided the alignment issues. I quickly designed a new plate that better clamped to the bike frame and produced it in record time.
Once the freewheel was re-secured, I wired up the front derailleur for a full transmission test.
I mounted the chain and checked the system.
The next road test
We were finally ready for the next road test. I checked the brakes one more time. I checked the transmission one more time. Finally, I checked the steering one more time. *#$^&*!$. The steering had failed again. What I thought was a loose set screw was actually a broken universal joint. The last universal joint in my possession. smh. The pins holding the joint together snapped off. There seems to be a lot of torque between the tires and the steering wheel.🤔
I really wanted to get to the next road test, already, so I fabricated a longer steering column to bypass the broken joint. It's not how I want it for race day, but it was good enough for a test.
Now. NOW, we were ready for the next road test.
All in all, it was a good test. The Hyperdrive upgrades are great! There was zero deflection of the drive axles. The chain between the freewheels and the Hyperdrive did skip a bit while coasting downhill. We'll need to take a look at that.
The driver's side transmission works great! I was able to shift through the main range of speeds in both the front and rear derailleurs without the chain breaking or falling off.
Steering...passed. I was able to turn the steering wheel, but it required A LOT of effort when the Falcon was standing still or moving slowly. We need to work out some kind of steering assist. I also think the breaking of the universal joint will not be a rare occurrence. We'll also need to beef up the steering in general.
All that being said, we cannot deny that the first transport is away!
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