gearing up less efficient?

by "less efficient" i mean it takes more energy out of you to ride the
same distance

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Gearing up?

2 obvious ways of doing it: a sun and planet gear, or a chain drive.

Both methods introduce some extra friction, so there is some small loss
of efficiency.

A chain-drive would normally mean a giraffe unicycle, which means a
taller machine, and more air resistance. On the other hand, there would
be less air resistance from the smaller wheel.

The gyroscopic effect would have little influence on efficiency, except
for making the unicycle directionally stable, and reducing weave.

The biggest bonus of a large wheel is that it is less affected by bumps
and hollows in the road.

The flywheel effect (which is not the same as the gyroscopic effect) of
a larger wheel will also tend to keep progress smooth.

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i see. THANK YOU😄

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Mikefule said:

*Gearing up?

2 obvious ways of doing it: a sun and planet gear, or a chain drive.

Both methods introduce some extra friction, so there is some small
loss of efficiency.

A chain-drive would normally mean a giraffe unicycle, which means a
taller machine, and more air resistance. On the other hand, there
would be less air resistance from the smaller wheel.

The gyroscopic effect would have little influence on efficiency,
except for making the unicycle directionally stable, and reducing
weave.

The biggest bonus of a large wheel is that it is less affected by
bumps and hollows in the road.

The flywheel effect (which is not the same as the gyroscopic effect)
of a larger wheel will also tend to keep progress smooth. *

I think the real effect is that the large wheel rolls over bumps better.
The flywheel effect changes the feel of the ride, but it takes more
energy to manage the heavier wheel than the flywheel saves you by being
smoother. (Ask the guys who put 29er tubes in their Cokers).

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ok cool😎

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tholub said:

*I think the real effect is that the large wheel rolls over bumps
better. The flywheel effect changes the feel of the ride, but it
takes more energy to manage the heavier wheel than the flywheel saves
you by being smoother. (Ask the guys who put 29er tubes in their
Cokers). *

This depends on the nature of the ride. Apart from minor changes in the
amount of the friction in the system, the effect of increased mass is
only noticeable when accelerating or decelerating, or ascending a hill,
or braking on a descent.

On a flat straight road, once the wheel is rolling, if anything, a
slightly heavier wheel will be easier to ride as it will even out the
very minor fluctuations caused by small bumps and changes in the
surface.

On the other hand, if your ride includes lots of speeding up, slowing
down, steering, climbing and so on, then the lighter the better.

Years ago, when I was a bicyclist, I remember reading details of a study
in which a tiam trials bicyclist did a (?) 50 mile ride, and then
repeated the ride in similar conditions a few days later, but with
several pounds of lead strapped to the bike. The second ride (with the
lead) was only a few seconds slower. On the other hand, if it had been
a hill climb, or a ride through city traffic, it would have made a huge
difference.

And yes, the effect of extra mass on the wheel rim is more significant
than extra mass on the frame, but the principle is the same.

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tholub said:

*I think the real effect is that the large wheel rolls over bumps
better. The flywheel effect changes the feel of the ride, but it
takes more energy to manage the heavier wheel than the flywheel saves
you by being smoother. (Ask the guys who put 29er tubes in their
Cokers). *

This depends on the nature of the ride. Apart from minor changes in the
amount of the friction in the system, the effect of increased mass is
only noticeable when accelerating or decelerating, or ascending a hill,
or braking on a descent.

On a flat straight road, once the wheel is rolling, if anything, a
slightly heavier wheel will be easier to ride as it will even out the
very minor fluctuations caused by small bumps and changes in the
surface.

On the other hand, if your ride includes lots of speeding up, slowing
down, steering, climbing and so on, then the lighter the better.

Years ago, when I was a bicyclist, I remember reading details of a study
in which a tiam trials bicyclist did a (?) 50 mile ride, and then
repeated the ride in similar conditions a few days later, but with
several pounds of lead strapped to the bike. The second ride (with the
lead) was only a few seconds slower. On the other hand, if it had been
a hill climb, or a ride through city traffic, it would have made a huge
difference.

And yes, the effect of extra mass on the wheel rim is more significant
than extra mass on the frame, but the principle is the same.

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Except that a unicycle wheel, unlike a bicycle wheel, is under constant
acceleration as it wobbles back and forth on every pedal revolution.

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I don't think a geared 20" would be much fun for riding long distances.
It would take tons more mental energy to stay on it. A larger wheel
enables you to be more mindless, and it gives you more time to make
corrections. A geared 20" would give you very little time to make
corrections before it dumps you. Technically speaking, a non-geared
system should be more efficient, but only under ideal operating
parameters.

<<begin threadjack>>

Tom, if you were willing to walk a block over, you could try riding a
geared coker

<<end threadjack>>

tholub said:

*Except that a unicycle wheel, unlike a bicycle wheel, is under
constant acceleration as it wobbles back and forth on every pedal
revolution. *

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tholub said:

*Except that a unicycle wheel, unlike a bicycle wheel, is under
constant acceleration as it wobbles back and forth on every pedal
revolution. *

But less if it's heavier, as the gyroscopic forces are greater.

And less, the better you get at riding.

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...and a geared wheel has less wobble over the same distance than a
non-geared wheel of the same size (which is, of course, irrelevant to
the original question).

tholub said:

*Except that a unicycle wheel, unlike a bicycle wheel, is under
constant acceleration as it wobbles back and forth on every pedal
revolution. *

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Another thought on this subject: Unibiker. He made a machine that was a
unicycle with derailleur gears. It was not dissimilar to a bicycle with
no front wheel or forks, but he adapted the seat and made other
modifications.

I guess (but don't know) that his wheel was 26 - 28 inches, but he
probably had it geared up to twice that.

I recall Unibiker posting reports as he aimed to cover 15 miles distance
in an elapsed hour.

Sadly no longer with us.

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Mikefule said:

*The gyroscopic effect would have little influence on efficiency,
except for making the unicycle directionally stable, and reducing
weave.
*

The gyroscopic effect has little effect on bicycle stability at typical
speeds and would have even less effect on a unicycle. The stability of
a bike comes from the geometry of the bike rather than the physics of
the wheels spinning like a gyroscope. The Wikipedia article on the
bicycle gives a good summary of 'bicycle physics'
(http://en.wikipedia.org/wiki/Bicycle#Bicycle_physics). Google will
also find other articles about the gyroscopic effect and balancing a
bicycle.

I don't see the gyroscopic effect having any significant influence on a
unicycle whether the wheel is geared up or not.

Reducing weave is more a factor of rider skill and the tire. Skinny
high pressure tires are skittish and will cause more weave. Fatter and
lower pressure tires track straighter and will have less weave. Tread
design, tire compound and the shape of the tire would also have an
effect. All of those factors would probably overwhelm any kind of a
gyroscopic effect from the wheel at the speeds attainable on a unicycle.

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john_childs said:

*

Reducing weave is more a factor of rider skill and the tire. Skinny
high pressure tires are skittish and will cause more weave. Fatter
and lower pressure tires track straighter and will have less weave.
*

I don't think the weight of the wheel and tyre has as much to do with
wobble/weave as does rider technique and short cranks.

To get maximal efficiency a wheel should have very little *wobble/weave.
This occurs at at different speeds for different people, usually as a
factor of how relaxed they are when pedalling. However, there comes a
point when even the steadiest riders will wobble- at the limits of their
maximal cadence for a particular crank length. Once you go past that
it's difficult to keep the wheel tracking straight because you're
fighting to stay on the Unicycle.

Which is also why you would wobble less if you were on a geared Unicycle
of same equivalent wheel size/crank length to a bigger wheel- because
your cadence is lower, there is greater control.

For example on the AUT- I could descend with much more control on 110mm
cranks than the 125's. At my speed limit for the longer cranks I was
wobbling all over the place, limbs flying everywhere despite my best
efforts to stay relaxed. The 110's require a much higher cadence before
I felt any wobble. Wobbling is an indication that you are putting a
twisting force on the wheel. The aim is to keep it tracking in a
straight line as much as possible.

(*by wobbling I don't mean tilting from side to side- although that
might be a factor. I mean riding in a squiggly line)

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so MY CONCLUSION IS....i think it will be worth it to build a geared up
giraffe, and i will expiriment with the weight proportions😄

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