The Hyperdrive is finally assembled! Appropriately named, this is the central drive for the Falcon. Our pedals drive freewheels that are connected to the input shaft of the Hyperdrive. The two pulleys on the input shaft run the road/mud gears. Although they both sit on the same shaft, only one pulley is secured to it at a time.
A long belt connects the front and rear pulleys together. This allows us to drive all of the wheels. The front and rear pulleys are sized so the large rear wheel spins at the same relative rate as the smaller front wheels. This is the road gear. The inside pulley connects the pedals directly to the road gear.
When I first tried assembling the Hyperdrive two weeks ago, I discovered the long belt was too long. And the next shorter available belt was way, way too short. The easiest way forward was to somehow increase the length of the path the belt takes around the pulleys. To take up that extra slack, I added another idler pulley. Luckily, I found a spot on the frame where I could attach a post for the new pulley.
I only needed one part to fix this, but it took almost two weeks to get it. After I drilled a hole and mounted the new pulley, I snaked the long belt around and tightened up the tension.
The road gear seems to work well. Nice.
The race's mud obstacle is a big worry. Many a sculpture has gotten hopelessly stuck in the mud. Every race veteran cautions us that the key is getting the gear ratio as low as possible between the pedals and wheels. On a typical mountain bike, you get a 1:3 reduction which is not enough to move through mud.
When our mud gear is engaged, the input shaft will drive a series of belts and pulleys that gives us a 1:16 reduction! This slows down the wheels' RPMs 16x, but also multiplies the turning force at the wheels by 16. If everything works as intended, the Falcon will very, very slowly, crawl through the mud. Glorious.
After mounting many, many pulleys, I installed all the short belts for the mud gear.
The mud gear also seems to work well, but of course there's a caveat. The road and mud gears converge at the front pulley.
They share the shaft that drives the front wheels.
It turns out that we need that common shaft to be able to drive all the wheels in the mud. But when we're on the road, it adds a lot of extra resistance.
Right now, the easiest solution I can think of is to only install the last belt of the mud gear when we are driving through mud. I also wanted to use the mud gear to help the Falcon get out of the water, but I think we'll need a better solution to do that.
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