# A bicycle can cut friction in half, called "Half Bicycle"

Discussion in 'Cycling Equipment' started by iwico, Oct 2, 2008.

1. ### Yojimbo_ Well-Known Member

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Mr. Q Gang

Interesting idea, but you need to research a little more on the physics of bicycle aerodynamics. Use Google.

2. ### iwico New Member

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Hi

After see the wheelie picture, you can see the front wheel is left from the ground about half meter. And there is no guard wheel C at back, if the cyclist turn bicycle back little bit too much, the bicycle will turn over. It need good skills and unsafe.

Purpose of this "Half bicycle" is to make the "wheelie" much safe and easy.

Regards
Mr Q Gang

3. ### iwico New Member

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Talk little bit more about the friction between wheels and the ground.

The friction between wheels and the ground, depending on 2 facts:

1. weight on the bicycle.
2. the area of tyre touch the ground.

If weight is same, then smaller area, less friction.

I sampled one before, about little unaired tube will increas friction lot. Every cyclist will understand this.

I have another sample: On race bicycle, the wheels is designed very narrow, Why? because it need to reduce area of the tyres touch the ground, to reduce friction. If as someone said, the friction only depending on weight, then why race bicycle uses narrow tyres?

This "Half Bicycle" not only reduce the area, it just make a wheel A left from the ground, whole area is disappeared. By this way it can cut friction in half.

Regards
Mr Q Gang

4. ### scuppy New Member

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Dude, repeating the same bad physics over and over again wont make it true. Friction between the road and the wheel is why the bike propels forward. Rubber deforms and wastes some of the energy and this is called rolling resistance. No one here is disputing reducing surface area in contact with the ground is a good thing. It is simply not the most significant factor.

5. ### alienator Well-Known Member

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Reducing the size of the contact patch is in almost every case, not a good thing, especially if you want to do things like go around corners, make emergency stops, and the like. The only real way to reduce contact patch is by over inflating.

I don't see the point of this "invention." It has absolutely no benefits that are apparent. The moments that such a contraption would generate would make it at least very unstable. Riding it with one wheel off the ground will increase the aero cross section causing it to require more power to overcome drag than a traditional bicycle. Riding it on two wheels will be just like riding an overweight bike, so in that case it won't be as good as a regular bike.

As I said earlier, the ability to avoid hazards and to make quick avoidance maneuvers will be non-existent. The moveable weight will destabilize the bike every time the bike hits a bump. If on one wheel at the time, the risk of a crash goes way up. I also think it's likely that a quick aggressive yank on the brakes, as in a panic stop, will overload the front wheel with excessive weight transfer from your moving weight. In two wheel mode that'll either mean doing an endo or if the pavement is slick, dirty, or etc, tucking the front wheel. Either way, flesh meets pavement. Then there's that bump or pothole that causes movement in the moveable weight when on one wheel which could destabilize the bike such that the bike rotates backward. Crash.

I seriously doubt there is any market for this thing, unless you count circus clowns.

It's apparent that not a single analysis has been done of this "design." You'll need a good barrister to protect from the inevitable liability claims.

6. ### sideshow_bob New Member

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McEwan, one handed and in trainers. Don't try that at home kids.

7. ### iwico New Member

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Hi McEwan

Could you tell everone here:

In wheelie position, do you feel friction between wheel and the ground is reduced? In other words, do you feel lighter than 2 wheels on the ground?

Regards
Mr Q Gang

8. ### artemidorus New Member

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You know, I really wouldn't count on Robbie reading this thread, diverting as it is.

9. ### alienator Well-Known Member

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It's absolutely clear that you do not understand:
• friction
• friction's role in the function of tires
• contact patch
• the magnitude of rolling resistance losses compared to other power losses in the bike/rider system
• equilibrium and unstable equilibrium
• moments and how moments couple with forces
• aero drag and its magnitude compared to other power losses
That's just a partial listing. You have answered, with no technical knowlege displayed, zero questions re: these topics. You certainly don't understand the dynamics, let alone the statics, of a bike/rider system.

As for McEwen and wheelies, he, like other humans, has a system that can respond to moments very quickly. You will fail to build a mechanical system that responds as quickly or even quickly enough to respond to said changes.

Clearly, you have no idea what you're talking about. You remind me of the guy in Youngstown, Ohio that claimed he had built a machine that had zero energy losses, one that proved invalid the Second Law of Thermodynamics. Of course his machine was only a 10% mechanical efficiency, but he said he was still "working out the bugs."

Oh, there is this tiny little nugget: When you transfer all the load on two tires to a single tire, guess what happens? That's right: hysteretic losses--rolling resistance--will at least double. In reality, it will more than double since the rear tire will experience much greater flex. Of course, a person could erroneously try to circumvent this by over inflating the tire and reducing, as your prone to say, the contact patch.. Guess what happens when you reduce the contact patch below it's nominal area?

10. ### garage sale GT New Member

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The extra concentration required to maintain equilibrium would not be insignificant. The brain is a glucose hog.

Plus, it would be much harder in a tuck because your torso would not be balancing over the rear wheel, as with an upright unicycle rider.

Aerodynamic drag is one reason not to have a tricycle. This contraption has three wheels, just like a tricycle. I wonder what the rolling resistance of a high performance trike is, but I bet it's not significantly higher than a road bike when all wheels are holding up the rider's weight.

11. ### alienator Well-Known Member

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I'm working on a revolutionary design for cars, wherein to improve gas mileage, the car will raise up and balance on the left rear tire. Also, the left rear tire will automatically grow or shrink to account for changes in driving conditions.

I'm also going to be marketing polished chrome, as well as gold plated, spinner hubs for monster trucks. This will certainly reinvigorate monster truck racing series and will no doubt increase truck sales in the US, Canada, and the Turks and Caicos.

12. ### dhk2 Active Member

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A guy rode the metric 100km route on a unicycle at our fall century this year. A buddy who was riding with him told me he was going 12 mph on flats, uphill and downhills. Sounds like an impossible feat to me, but apparently the rider is a tough endurance runner who just likes something different.

The high-performance trike I'm familar with has two front wheels with the rider sitting very low in between them. It's very fast downhill due to the minimal frontal area, but stability in hard cornering is a problem since it doesn't lean into a turn. Also, with seperate brakes on the left and right wheels, high-speed braking on descents is a real challenge due to the need to keep straight as the CG shifts forward.

I saw a friend crash his into a guardrail when he lost control on a twisty descent. He was behind us on the climb, but as we started down the descent, he smoked by us and passed at ~ 50 mph going into the second corner. A touch of the brakes was all it took to flip the trike and send him into the guardrail on the outside of the turn.

13. ### 531Aussie Well-Known Member

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McEwen said on local radio that the fans always want the wheelie, but, sometimes, at the end of long, hard stages of the Tour, he's so stuffed he thinks he might fall off if he does one, but he usually does them anyway, coz the people were goading him. See, maybe he's no so bad after all

14. ### iwico New Member

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Hi

Up to now, no a single cyclist (who can do "Wheelie") in here to tell us what happened when on Wheelie.

I like someone who can do the wheelie, to tell everyone here:

1. Do you feel the wheelie reduce friciton?
2. Is it easy to get the gravity point on the back wheel.
3. On wheelie, can you change direction?

On McEwen's wheelie picture, we can see some points:
1. He only need one hand on hand-bar, that means it is not very difficult to do it.
2. The road is not smooth, he can do wheelie on it. Not like someone said here if road surface is not smooth, wheelie will fall down.

Regards
Mr Q Gang

15. ### alienator Well-Known Member

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Yo. Go back to school. You have no clue what you're talking about.

Wheelies? Yup, I can and have done 'em. There not faster. Nope. No matter what your fantasies are, wheelies are not faster. Never have been and never will.

You will not that McEwen doesn't wheelie in races. Now why do you think that is?

Do you have any education? It doesn't appear so from your beliefs and statements.

16. ### Yojimbo_ Well-Known Member

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Ageed. Time to end this ridiculous thread.

Maybe the guy is pulling our legs - I can't believe anyone can really be that stupid.

17. ### dgregory57 New Member

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I used to ride wheelies a lot... so I do know what I am talking about...

However, let's look at a professional who rides for speed and efficiency, where I only rode them for fun. Yes, you can make turns while doing a wheelie, as far as friction, I could never tell, because you do them for fun, definitely not efficiency.

However, I think it is safe to say that the efficiency of a wheelie is disproven by the ease with which Mr McEwen does them. Since he can ride wheelies, and yet he still chooses to ride the race on two wheels, I think it shows that he feels it is the more efficient way to ride. If it was more efficient to ride on one wheel, he would do it.

My earlier post did show the picture for me initially, but it disappeared, but also your "safety wheel" is nothing new... do a google search for "bicycle wheelie bar" and you will see that they have been around since the 1960's.

Let's see if this one sticks...

18. ### alienator Well-Known Member

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Obviously, that Wham-o ad is from a time before personal injury lawyers were invented.

I also think when that kid grew up, he landed a role in Deliverance. He sure looks familiar.......

19. ### dgregory57 New Member

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I didn't say they were a good idea, just pointing out that they aren't a new idea.

I remember riding a bike with one once... a friend must have had one, but I don't recall who. As I recall it actually was harder to ride it on the wheelie bar than to just ride a wheelie without it. Of course, maybe it was because I wasn't used to it.

I thought the guy on that bike isn't the usual kid you would expect to see in an ad for that sort of product either... Maybe more of the before picture in a before & after ad of some sort. Of course, thinking back to the time frame, maybe he was the younger version of the outlaw biker of the 60's... I'm trying to remember what the neighbor bikers looked like when I first moved into the neighborhood in the mid 60's versus when I joined the service in the mid 70's. It was a time of significant changes in look for a lot of people.

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