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Old 2018-02-17, 01:57 AM   #31
tholub
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Originally Posted by Pinoclean View Post
I think you are failing to grasp this concept. This is saying that the best unicycle hockey player in the world will likely be better than his current self on a better unicycle, and gives you way to compare the two UNICYCLES for handling. Most riders want to perform as good as possible each time. Handicapping yourself with a wheel that through huge inertia cannot accelerate as fast for a given torque probably is not conducive to that rider being the best player they can be.

This is why track cycling spend millions of dollars to find the best setup and equipment for their riders. You can't necessarily make your rider better than someone else through equipment alone but you sure as shit don't want your rider on a bike with the aerodynamics of a schoolbus.


Nowhere does this say that equipment will make you a better player than someone who is currently better than you or vice versa. It doesn't say that the worst unicycle hockey player in the world on a good unicycle will be better than the best unicycle hockey player on the worst unicycle, that would be idiotic.

If you get two players who are almost identical in riding ability and skills then could it make a difference? Who knows. But as long as a rider knows he is riding the best setup possible then he doesn't need to worry bout that fact.
There are hundreds of thousands of bicycle racers in the world. The differences between the top riders are very small, so the differences in equipment make a substantial (though usually overstated) difference.

There are maybe 200 competitive unicycle hockey players in the world. The differences between the top riders are huge, so the differences in equipment don't make a substantial difference.

I am not disputing that a lighter wheel is better than a heavier wheel, all else being equal. I'm disputing whether it matters.

Speaking as someone who has been participating in unicycle sport national and world championships for 10+ years, who coached a world championship medal team, and who did a lot of experimenting with different setups during those years, including some weight weenie testing.

It just doesn't matter when you're playing.
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Old 2018-02-17, 04:52 AM   #32
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Originally Posted by finnspin View Post
The reason why track cycling spends millions of dollars on testing equipment, however, is that it helps them make many million dollars. That is the world we live in.

What interested me, is tangent to what you were doing, so i took your spreadsheet, modified it, fixed some stuff that is important for my calculations, but not yours (to convert from mm to m, you need to devide by 1000). What I calculated was the force needed to accelerate a 70 kg rider at 5 m/s^2 on different setups, and the force needed to do the same with a 75 kg rider. When leaving out crank setups (using a fixed gain ratio of 1, which would be equivalent as having cranks as long as your tire radius), the difference in force between the two rider weights is huge compared to the difference between different wheelsetups. I used a gain ratio of 1, since I was only interested in the comparison of tire weights, the change different cranks can do is fairly obvious. (I did also calculate the same for including crank length, which might be useful for something, I don't know what though)

Link to my spreadsheet: https://docs.google.com/spreadsheets...it?usp=sharing

Maybe I shouldn't be sharing this now, since I am super tired, and didn't really make it clean and presentable, but I am as sure that there aren't any mistakes in my calculations as someone that hasn't slept a lot in the last days can be at 2 am.

Why did those calculations interest me? Because for me, it's important to see how much of a difference something makes overall. So now I know, the influence of roating mass on your (straight line!) acceleration and deceleration capabilities on 20" and 24" unis is only small.
Nice job Finn. I don't know if I am the one to double check your calculations as I would have to look more carefully over the formulas and theory on why each was used (not a natural physicist) but looks good and informative.

I assume those sorts of calculations would also confirm that trials riders should lose bodyweight before worrying about dropping weight from their unicycle?

Oh and I didn't mean the companies spending millions on testing equipment, I meant the elite sporting institutes. They perform their own testing and make custom parts to improve performance.

Last edited by Pinoclean; 2018-02-17 at 04:53 AM.
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Old 2018-02-17, 05:03 AM   #33
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Originally Posted by tholub View Post
There are hundreds of thousands of bicycle racers in the world. The differences between the top riders are very small, so the differences in equipment make a substantial (though usually overstated) difference.

There are maybe 200 competitive unicycle hockey players in the world. The differences between the top riders are huge, so the differences in equipment don't make a substantial difference.

I am not disputing that a lighter wheel is better than a heavier wheel, all else being equal. I'm disputing whether it matters.

Speaking as someone who has been participating in unicycle sport national and world championships for 10+ years, who coached a world championship medal team, and who did a lot of experimenting with different setups during those years, including some weight weenie testing.

It just doesn't matter when you're playing.
The difference between riders in the top riders and the lower ranked riders is large, that is why only 7 teams compete in the A comp at UNICON, but in the top 4 or 5 of those teams in the A comp there is not "huge" differences between the individual riders abilities.

I guess you can not care about getting the very best out of the team your coaching but I suppose I try to look at unicycling in the way exercise scientists in professional sports do. I've ridden these wheels and the control and acceleration ability on the lighter setups is extremely noticeable. It's only my opinion but improving control and acceleration of a player is usually a benefit. Probably not as useful as having the individual player increase training from once a week to three times a week though.
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Old 2018-02-17, 06:09 AM   #34
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Originally Posted by Pinoclean View Post
The difference between riders in the top riders and the lower ranked riders is large, that is why only 7 teams compete in the A comp at UNICON, but in the top 4 or 5 of those teams in the A comp there is not "huge" differences between the individual riders abilities.

I guess you can not care about getting the very best out of the team your coaching but I suppose I try to look at unicycling in the way exercise scientists in professional sports do. I've ridden these wheels and the control and acceleration ability on the lighter setups is extremely noticeable. It's only my opinion but improving control and acceleration of a player is usually a benefit. Probably not as useful as having the individual player increase training from once a week to three times a week though.
It is way more important to be comfortable on your setup than it is to be marginally quicker. Sure, if you want to be a weight weenie, go ahead; like I said, I had one guy on my team who was a weight weenie. I don't think it made him a better player, but as long as he got his setup dialed in and didn't mess with it at tourney time, it was fine with me. As coach, I was way more concerned with getting people to make better passes and take better shots.
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Old 2018-02-17, 09:14 PM   #35
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Originally Posted by Pinoclean View Post
Rider weight makes a difference between riders, but the same rider will still feel the difference between equipment.
I disagree with that assertion - if by "feel" you mean feel the difference in acceleration of a different set up. IIRC in order for human perception to be able to detect a change in motion you'd require at least a 5% difference. Given the 70kg rider then for a 5% difference in acceleration you'd need a 3.5kg difference in mass on the frame of the uni, or 1.75kg difference in mass of the tyre/rim combo. However if we ignore the 36" tyres, then the difference between your heaviest and lightest combo is only 0.53kg, which would only result in a 1.5% difference in acceleration (for the same power input). There is no way a standard human can perceive that difference - which incidentally could also be achieved by losing 1kg of bodyweight - incidentally neither is 1.5% a "big difference in acceleration ability" as you claim in your first post. As already pointed out, the problem here is that by ignoring the rider you exaggerate the difference losing weight on the wheel makes.

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Originally Posted by Pinoclean View Post
I've ridden these wheels and the control and acceleration ability on the lighter setups is extremely noticeable.
Something might be extremely noticeable about them, but it sure isn't a 1.5% (or less) difference in acceleration. Is a 1kg difference in your bodyweight (which is within the normal daily fluctuation) extremely noticeable? Can you tell that you're dehydrated by how much faster you accelerate?
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Old 2018-02-17, 09:22 PM   #36
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Originally Posted by tholub View Post
It is way more important to be comfortable on your setup than it is to be marginally quicker. Sure, if you want to be a weight weenie, go ahead; like I said, I had one guy on my team who was a weight weenie. I don't think it made him a better player, but as long as he got his setup dialed in and didn't mess with it at tourney time, it was fine with me. As coach, I was way more concerned with getting people to make better passes and take better shots.
Definitely agree with this, a player constantly falling off is not useful just because they can accelerate quicker. In fact constantly falling off is one of the worst player attributes in hockey (possibly basektball too?). As a coach I would encourage my players to ride their unicycle in training (crazy I know), it is amazing how people become comfortable on a setup when actually practising with it. I know an entire swiss team changed their unicycles to mad4one's so they could have matching setups. My guess is by practising with the setup instead of riding it only at tournaments it became the new norm. Good riders tend to be adaptable much more than poor riders.

I would discourage any players from making drastic changes to equipment immediately before tournaments however. Not sure what your player was swapping out to change weight right before tournaments but thankfully players hotswapping out their unicycle rim and tyre for a tournament to get a light wheel build is pretty rare. They tend to just build the wheelset, practice with it at training, and then it becomes their new standard.

I also agree teamplay is always going to be the no.1 concern, you can't win a game if you don't score no matter how fast you are. These are just the 1%ers that exercise scientists consider. Perhaps for teams as close in skill as Bakau Boogaloos, SKV Mörfelden Joker, Mörfelden Gallier, Swiss A and Swiss B the 1% can make a difference.
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Old 2018-02-17, 10:11 PM   #37
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Here is one for all you physicists. I had a discussion with my wife about wheels. She decided that I definitely crazy when I told her that no matter how fast a wheel turns the point which contacts the road is always stationary.

Of course a point at the top of the wheel travels at the angular velocity of the rim plus the velocity of the vehicle or double the velocity of the vehicle. The rest of the wheel would be somewhere in between.

In terms of your calculations here I think you are all considering momentum which would average out because it is a linear relationship to velocity.

However, being a square law, the kinetic energy of top of the wheel would increase more than the bottom reduces it, so the total kinetic energy of the wheel would higher than a simple calculation of the rotational velocity.

Does that sound right or is my wife on the money?

BTW. On a flanged wheel there are locations that are always travelling in the opposite direction to the vehicle.
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Old 2018-02-18, 03:22 AM   #38
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Originally Posted by OneTrackMind View Post
Here is one for all you physicists. I had a discussion with my wife about wheels. She decided that I definitely crazy when I told her that no matter how fast a wheel turns the point which contacts the road is always stationary.

Of course a point at the top of the wheel travels at the angular velocity of the rim plus the velocity of the vehicle or double the velocity of the vehicle. The rest of the wheel would be somewhere in between.

In terms of your calculations here I think you are all considering momentum which would average out because it is a linear relationship to velocity.

However, being a square law, the kinetic energy of top of the wheel would increase more than the bottom reduces it, so the total kinetic energy of the wheel would higher than a simple calculation of the rotational velocity.

Does that sound right or is my wife on the money?

BTW. On a flanged wheel there are locations that are always travelling in the opposite direction to the vehicle.
Let's consult with Einstein's elevator: What if the wheel is spinning while in an elevator in free fall? Obviously the kinetic energy will be described by the formula for rotational kinetic energy, which is ( moment of inertia * angular velocity^2 ) / 2, which is the summation of the formula for translational/linear kinetic energy, which is ( mass * velocity^2 ) /2

Putting the wheel back on the ground, it should be clear that the kinetic energy is the same as if the wheel were in free fall. It doesn't actually matter that the bottom of the wheel is stationary relative to the ground; it's better to look at the system as relating to the center of mass of the wheel (the hub). If you spin the wheel in the air and then put it on the ground, you will experience its kinetic energy even if the velocity relative to the ground is zero.

Now, if the wheel encounters another object, you have to add back in the linear kinetic energy based on the relative velocity of the two objects. So it'd be ( I * w^2 ) / 2 + ( m * v^2 ) / 2, where v is the relative velocity.
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Old 2018-02-18, 06:17 AM   #39
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Originally Posted by tholub View Post
Let's consult with Einstein's elevator: What if the wheel is spinning while in an elevator in free fall? Obviously the kinetic energy will be described by the formula for rotational kinetic energy, which is ( moment of inertia * angular velocity^2 ) / 2, which is the summation of the formula for translational/linear kinetic energy, which is ( mass * velocity^2 ) /2
We are not talking General Relativity but Classical Mechanics.

That measurement would be for the kinetic energy measured from reference of free falling elevator. What we actually have is system that translocating as well as rotating relative to the system where it acquired that energy. The kinetic energy of the translocation is very real and applies to the frame too and must be contributed by the rider.
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Old 2018-02-18, 08:27 AM   #40
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We are not talking General Relativity but Classical Mechanics.

That measurement would be for the kinetic energy measured from reference of free falling elevator. What we actually have is system that translocating as well as rotating relative to the system where it acquired that energy. The kinetic energy of the translocation is very real and applies to the frame too and must be contributed by the rider.
What Einstein showed was that the concept of velocity is only meaningful in relation to other objects. Yes, a unicycle may be moving relative to the ground, or to the wall you're approaching, but v isn't meaningful unless you know the frame of reference. If you're moving 10m/s and you crash into another unicyclist moving 9m/s in the same direction, what's the kinetic energy released? Between the two unicyclists, it'll mostly be a function of the rotational energy, because v is only 1 m/s. But the ground you fall on might have an argument with that logic, because the unicycles are moving 9m/s and 10m/s relative to it.
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Old 2018-02-18, 09:05 AM   #41
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You are arbitrarily imposing an frame of reference that is moving with the wheel. The total kinetic energy acquired by the wheel is measured against the "stationary" ground since it began at zero relative to the ground. That is the amount of energy the rider must add to the wheel, not just the energy required to spin the wheel in one spot.

Alternatively you can choose any arbitrary velocity as zero. The kinetic energy acquired by the wheel as the uni accelerates to a new velocity must include the kinetic energy of the translocation.

Otherwise a wheel spinning in the air would have the same total kinetic energy as one rolling along the road at the same rotational velocity, which is clearly not the case.
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Old 2018-02-18, 12:32 PM   #42
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Originally Posted by OneTrackMind View Post
Here is one for all you physicists. I had a discussion with my wife about wheels. She decided that I definitely crazy when I told her that no matter how fast a wheel turns the point which contacts the road is always stationary.

Of course a point at the top of the wheel travels at the angular velocity of the rim plus the velocity of the vehicle or double the velocity of the vehicle. The rest of the wheel would be somewhere in between.

In terms of your calculations here I think you are all considering momentum which would average out because it is a linear relationship to velocity.

However, being a square law, the kinetic energy of top of the wheel would increase more than the bottom reduces it, so the total kinetic energy of the wheel would higher than a simple calculation of the rotational velocity.
That's completely correct. For a rolling wheel (with no slippage), the point of contact with the ground is stationary. Why? Because there is no slipage, so the ground and contact point of the wheel don't move relative to each other. This also means, a rolling wheel is not turning around it's center, it's turning around its point of contact, it's the wheels instant center of rotation. The speed of the center of the wheel is the vehicle/riders speed, and on top of the wheel it's twice that.

The kinetic energy can be seperated into a rotational component, and a linear component, so it's: Ekin = (mv^2)/2 + (Iw^2)/2

With I: the wheels moment of inertia, w: it's angular velocity
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Old 2018-02-18, 07:27 PM   #43
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For a rolling wheel (with no slippage), the point of contact with the ground is stationary. Why? Because there is no slipage, so the ground and contact point of the wheel don't move relative to each other. This also means, a rolling wheel is not turning around it's center, it's turning around its point of contact, it's the wheels instant center of rotation. The speed of the center of the wheel is the vehicle/riders speed, and on top of the wheel it's twice that.
This is maddeningly simple, and yet somehow counter-intuitive! Until you stop and think about it, of course. It was explained to me a long time ago, but reading this thread is the first time I have thought about it since I learned to wheel walk. It is why a wheel walker has to walk so fast just to roll slowly along, and it's part of why the maximum distance anyone has ever wheel walked (according to an anecdote on this forum) is only one mile. Wheel walking is tiring because it is inefficient. I have trouble wheel walking more than 100 meters or so, and by then I am usually too tired to return to the pedals properly.

I wonder if anyone has ever set up a geared wheel walking arrangement- in other words, a unicycle with a small wheel (or two) stacked on top of a second (or third) much larger wheel. In terms of the mechanics, I suppose geared wheel walking would not be that different from pedaling, but it might be more fun, or a good way to stir up a crowd.
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Old 2018-02-19, 03:14 AM   #44
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Wheel walking is tiring because it is inefficient.
Sit in a chair, lift your feet slightly off the floor, then air-wheel-walk on an imaginary wheel. I tried it, and I started feeling tired right away. I think wheel walking is inefficient because we're lifting our legs up in the air as we hold them out in front of us, and there is certain weakness to this position. We are accustomed to getting more exercise pushing down with our legs, rather than pulling up with them. Good WW technique is pushing the wheel forward without exerting much downward force. But without the downward force, we are left holding up the weight of our legs in this awkward position. To pass the 1 mile mark, maybe the legs have to rest on the wheel sometimes. A great hill climber told me that on long uphills, you must not spend every second standing on the pedals; you have to spend some time, even a moment, sitting on the seat. I imagine the same concept could apply to wheel walking. The unicycle frame would have to be modified into a giant arc, moving the crown forward, so the rider could walk directly on top of the wheel, putting all their weight on the feet without necessarily pushing the unicycle forward. I think someone could wheel walk more than a mile on such a unicycle, because the activity would be more like walking. I don't think wheel walking is inefficient because of the number of steps necessary to travel a short distance; rather, I think it's the isometric position we have to stay in while wheel walking that is hard. The number two comment I get from non-riders (after variations on WYOW) is I bet that's good core exercise. Wheel walking definitely counts as core exercise.
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Old 2018-02-19, 06:44 AM   #45
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I thought this forum was for nerds, I am amazed at how dismissive everyone is of someone trying to calculate wheel characteristics of unicycles.
Yes, bad nerds! Though the OP's "research" was a lot more random (and pointless) than yours. We're not even sure if he already knew how to ride a unicycle, though I got the impression he didn't.

So you have raised the physics study nerdliness to a new level now, but for something a little more functional. By making it about hockey, you have given a specific set of requirements for the riding, along with a fairly specific environment in which this riding takes place. Basically the difference being riding surface, but otherwise most things being the same.

I'm not a uni hockey expert, but my gut feeling is that the best wheel would be light and responsive, but that I wouldn't want a skinny tire. Also I wouldn't want a non-sturdy wheel; I'd much rather haul a little extra mass around than deal with wheel problems mid-game. Some of that probably comes from my professional performing background, where we really, really don't want our gear to break, and I feel hockey would be a similar situation, at least at the tournament level.

Sports tend to grow and become more rarified/specialized. In the future, I think hockey (and basketball) players will pay more attention to equipment, looking to optimize performance. Even if most don't, some riders or teams will find it fun to experiment.

When I was real big on Track racing, I had a special 24" uni built for me. The Miyata frame was standard, except for beefed-up bearing bolts; at the time they were small and tended to strip. But I used a modified, lightweight aluminum seatpost that had a gusset to keep it stiff for acceleration. Tom Miller made me a hub that was actually hollow, and a little lighter than the usual ones. My wheel was on the skinny size, but not like those 26x1" wheels some current racers use (I don't think that would have been legal back in the early 90s). I think mine was a 1 3/8" setup.

At the same time I was also focused on training/fitness/body weight. I won a lot of races, and enjoyed my cool Track uni until it was stolen at Unicon X.

I always found it kind of interesting that 20" is almost exclusively used by hockey players, while 24" is almost exclusive in basketball. I think it's because the 24" wheels don't get in the way as much for basketball, but they do more in hockey. I would prefer the speed for both sports, but when watching top hockey teams, they seem to do just fine on the 20's.
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