Sliding weight to ehhace flywheel.

And what is the point of adding the weights in the first place? I could
only see this being useful if you wanted to maintain high speeds, not
getting to them. Maybe i'm confused though.

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hecklar said:

*And what is the point of adding the weights in the first place? I
could only see this being useful if you wanted to maintain high
speeds, not getting to them. Maybe i'm confused though. *

The higher weights add stability to the wheel when riding at high
speeds. This is why some people like cokers so much. By making the
weight slide out, it allows you to start riding with a wheel with a
smaller rotating inertia then a wheel with static weights on the rim.

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Oh, OK, that makes sense then, but you still have to carry around the
extra weight. It's probably not worth gaining the extra stability for
the cost of spinning around that extra weight.

Are people adding weight to their Cokers, now, for the extra stability?
If so, then this would be a good idea.

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I personally think this is an excellent idea. The only isse I can see
with it is that you would have to springload the weights so they didn't
drop to the bottom of the wheel when you first start, although this
isn't a huge deal.

What would be cool is to be able to control the distance between the
axle and the weights. That way when you *really* want an extra boost in
speed, you could simply pull the weights to the center of the wheel.
That'd kick your rpms up insanely quickly, althought it may also kill
you...

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Couldnt you just put some fishing weights on the spokes, that would
almost instantaneously whip to the rim, and with fishing weights, you
could get them easily, cheaply and in many different weights and sizes.

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There was a company a few years ago that made a 6 speed shifting
bicycle. It worked the same way that daino149 is talking about. As you
pedaled the bicycle faster, it would cause the weights which were
connected to the rear derailer to move outward making the derailer move
to a higher gear. When you slowed down, it would shift back down to the
lower gears.

The company has since gone bankrupt.

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Catboy said:

*Couldnt you just put some fishing weights on the spokes, that would
almost instantaneously whip to the rim, and with fishing weights, you
could get them easily, cheaply and in many different weights and
sizes. *

Why not just fill the tire tube with water instead of air?

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"daino149" <[email hidden]> wrote in
message news:[email hidden]...

Quoted message said:

I was wondering if anyone has considered using a sliding weight to
enhance the fly wheel effect of large diameter unicycle wheels.

The way I picture it working is having a light weight (few ounces) that
starts at the hub (or close to it) when the wheel is at rest, and it
slides out as speeds pick up. It would allow the wheel to accelerate
faster then if the weights started out on the rim.

As you probably understand, the stability effect of your rotating wheel
increases with speed anyway, Your lead weights would be adding to the rim
and tyre weights, but unless they are a significant proportion of the
tyre/rim weights they will have negligible effect.
One weight would throw you out of balance, so you would need at least two.

It is an interesting conversation piece, but I doubt it will have much
practical value. I would suggest a heavier tyre and sacrifice that bit of
acceleration for the added stability if you need it. Remember of course
that you add straight line stability, and thereby reduce manoeuverability.

Nao

daino149 said:

The way I picture it working is having a light weight (few ounces) that
starts at the hub (or close to it) when the wheel is at rest, and it
slides out as speeds pick up.

At the bottom part of the cycle, gravity helps the weights go towards
the rim, while at the top part gravity works the other way. So at
intermediate speeds, all the weights may yoyo back and forth. How
annoying would that be?

I assume that the weights are spring-loaded to stay near the hub?
Since the "centrifugal force" is low near the hub (low radius) you
need quite a lot of rotational speed before they move out, if at least
the spring is strong enough to overcome gravity.

I like gerblefranklin's idea about a boost derived from conservation
of rotational momentum. Not so much for a unicycle (you have to be
aple to pedal at that speed anyway) but it would be great for a bike
or car. Not very practical though, since you have to lug around all
that weight all the time, but it might be handy for the human-powered
speed record?

Klaas Bil - Newsgroup Addict
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Klaas Bil said:

*On Fri said:

The way I picture it working is having a light weight (few ounces)

that

Quoted message said:

starts at the hub (or close to it) when the wheel is at rest, and

it

Quoted message said:

slides out as speeds pick up.

At the bottom part of the cycle, gravity helps the weights go
towards
the rim, while at the top part gravity works the other way. So at
intermediate speeds, all the weights may yoyo back and forth. How
annoying would that be?

I assume that the weights are spring-loaded to stay near the hub?
Since the "centrifugal force" is low near the hub (low radius) you
need quite a lot of rotational speed before they move out, if at
least
the spring is strong enough to overcome gravity.

I like gerblefranklin's idea about a boost derived from conservation
of rotational momentum. Not so much for a unicycle (you have to be
aple to pedal at that speed anyway) but it would be great for a bike
or car. Not very practical though, since you have to lug around all
that weight all the time, but it might be handy for the
human-powered
speed record?

Klaas Bil - Newsgroup Addict
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You seemed to see the same problems as i've been seeing, but I just
noticed another. Assuming we can properly adjust the springs to overcome
gravity but still move to the rim at the right speeds, we have to again
take into accout conservation of angular momentum. As those weights move
outward, they will have the effect of slowing the wheel down. Thus, you
don't really have a way around the severly reduced acceleration.

I think my idea could work on a bueshifted or jackshifted coker, since
you'd them be able to spin the wheel MUCH faster.

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In my camp, we're still trying to make wheels as light as possible.

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One on one said:

*Why not just fill the tire tube with water instead of air?

*

Water inside the tire would add weight but would probably slow you down.
Since water is not a solid it would have a tendency to stay at the
bottom of the tire. Even if you could get all the air out and fill the
tire completely with water, I think you would still feel the effect of
the water moving inside the tire. When you start moving, the tire would
move but the water would create a dragging effect until the water's
rotational speed catches up with the tire. However, what if you could
fill the tire with water and freeze it?

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mucRider said:

*However, what if you could fill the tire with water and freeze it? *

That's just asking for a blowout. Liquids don't have variable volumes,
so a tire filled with water would absorb no shock and be unable to
comperss. Then, since water expands when it freezes, as it froze the
pressure onthe tire would increase, eventually blowing up the tire.

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gerblefranklin said:

*Liquids don't have variable volumes, so a tire filled with water
would absorb no shock and be unable to comperss.*

An air filled tire is not changing in volume (ok, it does a little, but
it's an insignificant amount), it's just being displaced. Water will
still absorb shock, but it will be different as the water can't be
displaced as quickly as air.

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Gilby said:

*An air filled tire is not changing in volume (ok, it does a little,
but it's an insignificant amount), it's just being displaced. Water
will still absorb shock, but it will be different as the water can't
be displaced as quickly as air. *

Install a refrigeration device to cool the water in the tire to 39.2
degrees (waters highest density) once the wheel gets up to speed. That
way you have changing weight without the problem of springs, shock
absorption, or the expansion of freezing.

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gerblefranklin said:

*That's just asking for a blowout. Liquids don't have variable
volumes, so a tire filled with water would absorb no shock and be
unable to comperss. Then, since water expands when it freezes, as it
froze the pressure onthe tire would increase, eventually blowing up
the tire. *

it would still absorb some shock because the tube is made of rubber, and
is stretchable. when you hit a bump it would just stretch at the top of
the wheel to absorb it.

but, as has already been said, it would take time for the watter to
catch up with your wheel when you accelerate, meaning lots of friction.
it would also keep going when you tried to stop, making it hard to stop.

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I rode Florian's 24*1.5, effective 36, today and compared to a Coker it
has much less angular momentum (fly wheel effect). This is much better
than having more. Turning and leaning both require changing direction
and you get more giroscopic effect on the larger wheel. This didn't
seem to be a good thing.

What having all the geared uni's next to eachother seemed to show even
more was that to accelerate or slow down you have get your center of
mass off center exactly the right amount and then try and move the wheel
back under you. A heavier wheel makes it that much harder to get the
wheel under you when you start to fall so it amplifies any bumps,
wobbles or errors rather than helping absorb them like it would in a car
(where you don't have to worry about getting the wheels back under the
car.)

Josie

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A basic tenet of bike racing is that the best weight to get off the bike
is rotational weight. For bikes, lighter is faster, and the best place
to remove weight (as long as it doesn't make things break) is from the
wheels.

Adding more weight might make for a more comfortable ride, but would be
unlikely to make for a faster ride, except possibly over very short
(sprinting) distances.

Having a pair of weights that helped to compensate for the "wobble
factor," that which makes the wheel want to zig-zag left and right,
might be a positive thing though. Helping the wheel go straighter might
reduce some of the rider's fatigue in high speed pedaling.

On the other hand, when I go fast on my Coker I don't notice a wobbling
problem. It's there, but the heavy Coker wheel straightens itself out
pretty well. If we ever get lighter Coker tires/wheels, we will see more
wobble.

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johnfoss said:

Adding more weight might make for a more comfortable ride, but would be
unlikely to make for a faster ride, except possibly over very short
(sprinting) distances.

How would (more) weight help here? I would rather say that when
accelerating, weight holds you back. Conversely, once you are at
speed, weight wouldn't matter (at least in an idealised world: no
acceleration/deceleration, no cornering, no bumps, no increased air
friction).

Quoted message said:

Having a pair of weights that helped to compensate for the "wobble
factor," that which makes the wheel want to zig-zag left and right,
might be a positive thing though. Helping the wheel go straighter might
reduce some of the rider's fatigue in high speed pedaling.

That, and also if it straightens out the path, the actual riding
distance from A to B is a little shorter.

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