Electrically Actuated Parallel Quarter Wheel

The tension-spoke wheel common to most bicycles, just one fragment of genius that fell from George Cayley's mind on the way to inventing controlled manned flight, has been around for a while now<link>.

Recently, enterprising folk have fitted electric motors to the hubs of bicycle wheels<link>, in the time honored- tradition of Johnny-Foreigner combining two British inventions. The hover-lawnmower<link> is a flawed example of this concept, once the gardener has removed several toes, they often complain about having to manually arrange the grass into pleasing stripes. I digress, the electric bicycle hub motors are clearly capable of rotating the wheels at high speeds, my delivered food has never been hotter or more prompt.

The job of these hub motors is to act as propulsion. This is silly. Bicycles already have a delivery person as propulsion and the hub motors often propel the bicycle faster than the gearing would allow. Consequently, I am being visited by a progressively fatter Chinese gentleman as the weeks go by. If this trend may be extrapolated, Chinese obesity could cause a worrying global imbalance, the counterweight population of the American Midwest are already as massive as practicable.

Instead of propulsion, the hub motor could be used to solve some of the bicycle wheel's deficiencies. Anyone who has had to move a bicycle by car, plane or perhaps get one delivered, will attest to the fact that they're a bloody awkward shape. I believe the wheel is the main culprit here and could benefit from some simplification. The most obvious step would be to remove a wheel. The unicycle is a step in this direction but widespread deployment would force current unicycle enthusiasts to resort to carrying a large flashing sign with "pay attention to me" written on it. You can make the wheels smaller, such as those found on folding bicycles, but the small radius means the wheels fall more completely into holes in the road making for a less comfortable ride.

Now, when considering the bicycle wheel, you will notice that the whole top 1/2 is just hanging around taking up space, you only need the bit between the hub and the road. Take away half the wheel and the bicycle becomes much more compact. The problem is that upon rolling forwards, you run out of wheel. Realistically you'd have a range of about 1 metre. This is smaller than the distance between Panda Garden and my house and therefore unsatisfactory. Walking is similar, you take a step, and there you are, about a metre forward, often short of your destination. Very disappointing. Now, nature has provided us with a whole extra leg-foot apparatus. With this we take a step, and while that is going on, we get the other leg ready to go for step number two. Very clever, nature has been peeping at the plans for the Gatling gun.

So, we have a half wheel, on top of that an additional half wheel to be used while the first half goes over the top to the front. Now, the total amount of wheel here is creeping dangerously close to 1, which was the original number of wheels per wheel on a bicycle. Despite all my careful logic, I don't want to be accused of simply reinventing something.

Can we improve? What if we use a pair of 1/4 wheels? The first 1/4 wheel can be used to support the bicycle as it rolls forward, as it rolls further, the second 1/4 is already waiting right in front of the first forming a pleasing half- wheel. As the weight of the bicycle is transferred to the second 1/4 wheel, the first is now free to race around the top at 3 x the rate of its companion to be ready for the weight to roll onto it. Then the whole cycle repeats. To accomplish this, each 1/4 wheel is driven by a relatively low power stepper motor in each side of the hub. The hub motors are controlled by a simple microcontroller which takes direction and position information from ABS or crank position-style tone wheels. <link> As you roll forward, the controller counts off degrees of the 1/4* wheel and direction info can be obtained from extra/missing teeth**. It's pretty trivial compared to the Segway balancing.

As for the space saving, the 1/4 wheel segments could be next to each other, rather than inline. The wheel could then be stowed in 1/4 of the space with the down side of a little left-right motion as the weight transferred from one section to the other, however the front and rear wheels could be 180 degrees out of sync. to make it less noticeable.

*I'm aware that this has now become a compression- spoke wheel. Perhaps Cayley is spinning in his grave, suspended by wire equidistant from the circumference of his casket.

**This could also be done from the Hall-effect position sensing in the hub motors themselves. Each motor is fixed to one fork-leg and its position and direction relative to that is known. This information is enough for the second motor.