h a l f b a k e r y
Not so much a thought experiment as a single neuron misfire.
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The tension-spoke wheel common to most bicycles,
one fragment of genius that fell from George Cayley's
mind on the way to inventing controlled manned flight,
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
arrange the grass into pleasing stripes. I digress, the
electric bicycle hub motors are clearly capable of
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
silly. Bicycles already have a delivery person as
and the hub motors often propel the bicycle faster than
gearing would allow. Consequently, I am being visited by
progressively fatter Chinese gentleman as the weeks go
If this trend may be extrapolated, Chinese obesity could
cause a worrying global imbalance, the counterweight
population of the American Midwest are already as
Instead of propulsion, the hub motor could be used to
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
obvious step would be to remove a wheel. The unicycle
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
You can make the wheels smaller, such as those found on
folding bicycles, but the small radius means the wheels
more completely into holes in the road making for a less
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
destination. Very disappointing. Now, nature has
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
wheel to be used while the first half goes over the top to
the front. Now, the total amount of wheel here is
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
Can we improve? What if we use a pair of 1/4 wheels?
first 1/4 wheel can be used to support the bicycle as it
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
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
motors are controlled by a simple
microcontroller which takes direction and position
information from ABS or crank position-style tone
<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
little left-right motion as the weight transferred from
section to the other, however the front and rear wheels
could be 180 degrees out of sync. to make it less
*I'm aware that this has now become a compression-
wheel. Perhaps Cayley is spinning in his grave, suspended
by wire equidistant from the circumference of his
**This could also be done from the Hall-effect position
sensing in the hub motors themselves. Each motor is
to one fork-leg and its position and direction relative to
that is known. This information is enough for the second
Tension Spoke Wheel
[bs0u0155, Sep 13 2016]
[bs0u0155, Sep 13 2016]
Upside-down Lawn Dethcopter.
[bs0u0155, Sep 13 2016]
[bungston, Sep 13 2016]
Wheg, the optimized surface wheel for uneven surfaces
On the technology s...gnesium or the like
this is the word Wheg at an image search engine [beanangel, Sep 15 2016]
youtube of a wheg
[beanangel, Sep 16 2016]
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||Gets my post-for-the-day award.
||Really all you need is a pedal-powered biped walking
machine of some sort.
||// What is a gating gun? //
||An administrative weapon to keep students on campus.
||//What is a gating gun?//
||Fixed. I think planning a trip through Wales wore our my "l"
||I like this but the 1/4 wheel scheme is profligate and wasteful. Really, the intersection of wheel and substrate could be considered a point; in practical terms probably a square inch. A rod of appropriate length and diameter would serve, extending down from the hub to the ground.
||A second rod races up over and around, powered by that hub motor, and receives the weight of the cycle as it rolls forward off the first rod. Repeat. You will want to stay out of the way of these rods which move fast.
||One could test this initially using a wheel made entirely of rods. Each successive test rider must remove one rod before riding, according turning up the hub motor speed to compensate.
||Whomever crashes the bike first then must ride a related hub motor-driven device which has been retrofitted into that other English invention, the spanking machine.
||A standard bike traveling at 30mph, a fair lick I know, but
we may as well test it, will require 530 1" rod ends per
second. For two spokes, each will have 190 microseconds
to traverse the 43" (1.09m) circumference of the wheel it
is simulating. This means it must average 5737 m/s.
Assuming linear acceleration from and to 0ms, we have a
peak speed of 1376kph. Which is Mach 1.12. Assuming
your spoke is about 30g, you're going to need to have
about a 7 ton forward/backward force oscillation from
accelerating/decelerating the spokes into position. A bike
wheel with supersonic tires, I like it.
||What if the rods extended and retracted through the hub so that you'd only need half a wheels worth of them and they'd only had to transverse the diameter in half of a revolution?
||I think the math applies to the 2-rod wheel. By necessity I will stick with gesturing and shouting but it is certainly elegant, math.
||I see that the rods must move fast. Clearly the issue is that the circumference the tip must traverse is too great. But one can make the necessary speed as much slower as is necessary by reducing the circumference of the wheel. Can I too do some math? Let's see.
||The current circumference is 1.09 m which yields a necessary speed of 1376 kph. Bs0u0155 is comfortable with 30 mph which I convert to 48 kph: approximately 1/28th of 1376. 1.09/28 = 0.038 which we can round to 4 mm. So a unicycle with a 4 mm diameter wheel would allow a nice leisurely rod progression, without the sonic booms and broken windows.
||Or one rod could retract slightly into the hub then swing round a couple of degrees against the direction of rotation so that it now leads the other rod. It would look more like a walking action with the two rods continually stepping over each other.
||Of course all these variations defeat one of the main advantages of a complete spoked wheel which is that the spokes are all in tension and therefore structurally efficient.
||Riding the weight of a person on the tip of a near ballpoint
pen might cause some damage to whatever road surface
you intend to ride, and the person who tries to ride it...
||/ Riding the weight of a person on the tip of a near ballpoint pen /
||Mr Steele: the tip end goes downward, away from you. The top side, where you are, is comfortably padded with one of those jelly banana seats. Your concerns about the road may have merit, and if you like you may ride along one rail of that disused railway track in your neighborhood, which they should convert into a bike path anyway.
||This sounds like a cybernetic wheg [link] the thing is that as the unused area of the wheel moves towards the center there is a velocity increase as well, which the computer directed electric motor could compensate
||My first thought was that a square inch rod is going to fall into a hole in the road just fine, regardless of any imaginary wheel it's part of, but now I'm not sure. What would happen if one of the wheel fragments ends up over a hole, and then you try to advance the other wheel fragment to the front but there's still weight on it?
||[beanangel] your link doesn't work.
||The youtube link is new and functional, it could be strange browser effects, I cannot edit the other wheg reference, even to delete it.
||Even trying to flag the link malfunctions.
The WHEG is very cool.
It totally reminds me of 'The Animal' toy from when I was a kid though. [link]
||They had some really cool toys back then.