by definition the wheel is heavier than a regular wheel. the big question is whether the extra weight at the perimeter is more of a benefit during downhills than the offset from the extra overall weight going up.

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Trek Madone 5.9SL
Felt B12 (sold)

I won't believe a word till I read Frank Day's and Dev Paul's opinion.
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It doesn't really matter what Phil is saying, the music of his voice is the appropriate soundtrack for a bicycle race. HTupolev

wouldn't the "spring" part of the moving weights make this illegal for competition?

Good for low speed accelerations.

I can't imagine how bad this wheel would be for sprinting though... you're already at close to top speed; to accelerate would be even more difficult.

Plus by conservation of rotational momentum, you'd still take the same amount of energy to accelerate compared to a similarly weighted wheel.

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Chewie
Slowtwitch Aeroweenie since '06

Seems to me it is another way to waste energy better spent in moving yourself and the bike forwards. All the energy comes from the rider irrespective of the bells and whistles attached to the bike, the frame, the wheels etc. The transference of the energy through the bike into forward motion is what is important. This is a closed system, so you do not want to divert energy anywhere that is not involved in moving you forwards to the start of the run. Having springs and moving weights just sucks up some of that energy, so it may "feel" better to you, but assuredly you are losing energy and and speed. Keep it a simple as possible. You , bike road. leave the bling home.

sounds clever, but there is no way a bike with these wheels would be faster in a roll down test if the "control" bike was aerodynamically equal and also had wheels that were identical in total mass, wheel mass, and starting wheel moment of inertia. actually, i think a bike with these wheels would likely be slower.

why?

it can't be faster, otherwise it is a perpetual motion machine. where does the additional energy come from?

then, if the weights move out toward the periphery of the rim during higher speeds, they're gonna have a big aero penalty because the wts. have substantial volume and because near the spoke ends the wheel is traveling at very high speeds, which means more drag.

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Where would you want to swim ?

Unless there is a disc cover?

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Dick

Take everything I say with a grain of salt. I know nothing.

Yea,

But that is what that campy disk was that you used to fill with water...What was the name of that wheel...

Stephen J

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I believe my local reality has been violated.
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Happiness = Results / (Expectations)^2

the disc cover would work for the aerodynamic penalty, but if the 'control' bike also had a cover, there would be no gain.

but that still doesn't solve the perpetual motion machine problem ...

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Where would you want to swim ?

No clue really but my guess is that if it really saved more time than a $1,000.00 aero wheel they would be trying to get more than $25 for a set.

That's idiotic.

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Jonathan Blyer,
ACME Bicycle Co., Brooklyn, NY

I was just referring to the aerodynamic penalty.

However, I don't think that they are talking about perpetual motion. One might conceive of a slight transferrance of angular momentum to the first few spins after a decent. There would be some penalty for the slight increase of angular momentum and weight on the climbs, I would suspect. The question is the net gain or loss. I haven't a clue, but it does look like some of Sheldon Brown's gadgets.

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Dick

Take everything I say with a grain of salt. I know nothing.

I love inventions that defy the laws of physics.

I could make an argument for a marginal improvement on a rolling course. The increased momentum on the downhills should help keep the speed up longer when transitioning to the uphill. But, it does seem there would be an overall aerodynamic penalty such that it is hard to imagine "up to" a 5 sec per mile improvement when everything is considered. I doubt there would be much benefit but they have some heavyweights saying nice things about them. Not sure what that means so I will wait for the studies.

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Frank,
An original Ironman and the Inventor of PowerCranks

It might not defy them.
Remember that you waste a lot of energy fighting wind on descents. If a little of this energy is transferred to the angular momentum of the wheels instead of the wind resistance, one MIGHT not suffer any significant loss of energy/momentum. That slight extra angular momentum, MIGHT give a little boost at the bottom of the descent, on the roll out as the speed decreases. MIGHT.

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Dick

Take everything I say with a grain of salt. I know nothing.

Unfortunately, we have to obey this little thing called the law of conservation of momentum. It uses energy to move those weights. As the weights move out, the wheel loses speed. You dont get free energy. You might have some instances of instantaneous benefit, but overall... this wheel will slow you down. You are always carrying more weight on your wheel. It always takes energy to move those weights. Your legs, and gravity, put energy into the system... friction "removes" energy from the system. The springs are changing your energy into heat every time they contract and expand.

Without going into a 10 page thesis on Newtonian physics, simply put...this can not make you faster.

I'm aware of Newtonian physics. I aced physics and calculus.
Once the weights are 'out' you have no more loss of momentum, except by air resistance or loss of slope. Meanwhile, the descent will keep your speed up until you lose speed, so there will be no net change in angular momentum because you ain't going any faster. (Most of your potential energy gained on climbing is lost to air resistance on the descent.) So in essence, if this works, it would simply transfer some of your potential energy lost to air resistance to angular momentum, which would be expended at the bottom. As you slow down, they will continue to keep the wheel spinning, as would a heavy wheel, but they angular momentum is maintained until the air resistance slows the bike, at which time they will move inward, like a skater pulling in his arms to increase his speed. (But, obviously, the weight an air resistance of the bike would not allow any speed up, but rather, a slight kick in kinetic energy of the bike with the loss of angular momentum of the wheel. So, I could see a possibility that this brief period of time at the bottom might give you a few extra ergs of horizontal momentum at the expense of the angular momentum . How much one would lose pulling them back up the hill again is another matter. What's the net?

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Dick

Take everything I say with a grain of salt. I know nothing.

All I have to say is... energy in equals energy out. If this wheel made you faster, it would not obey this law.

But, but....Dirk Friel set his fastest time ever on a certain TT course last summer using those things! linky

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http://bikeblather.blogspot.com/

Sorry its not quite that simple. In theory for this wheel to work it dosn't have to defy any laws of physics. I'm not however claiming it does work, I suspect the losses would likely out weigh any gains.

What this wheel is a speed "smoother".

Consider two cyclists doing the same course they both average 30km/h (there from the modern world where we work in metric units). The first cyclist maintains a constant speed of 30 km/hr, the second cyclists speed varies for simplicity lets say he spends half the time at 20km/hr and the other at 40km/hr.

So they both average the same speed, so do they both use the same amount of energy?
No the cyclist who maintains a constant speed reuires 11% less energy to fight wind resistance due to power squared law.


So if this wheel can reduce the high speed sections by storing energy (in a "fly wheel") and increase the speed in the low speed sections it could in theory reduce the energy required.
Whether this wheel achives this I have no idea, I suspect the course would have to be just right (gently rolling, no breaking) and even then I suspect just using a wheel with a heavier rim might do just as much.

if i remember correctly from all those years of physics....... wouldn't this be what somene already said is a closed system (or something like that)

for a simple test one could roll a solid cylinder down an incline (do some measurements: speed, time, acceleration, blah blah blah)
then roll a cylinder of the same mass and outside diameter only hollow down the same incline (do some more measuremnts.....)
compare.

i will put in my guess....... they will accelerate at the same rate.

just my $0.02

With Tom A.'s endorsement, I just ordered a set.
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It doesn't really matter what Phil is saying, the music of his voice is the appropriate soundtrack for a bicycle race. HTupolev

Has anyone heard about any pricing points yet?

I found some for $5.00

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What if the Hokey Pokey is what it is all about?