Graeme Obree: Hand-building the fastest bicycle in the world

[bikerjohn]

@Lazarus

Hi again, As for research I basically just googled various shapes aero dynamic drag factors the conclusion of which backed up out theory of the cigar/teardrop having the lowest drag factor and therefore the least resistance.

If you've seen both video interview's so far of Graeme's new design his theory started for the simple factor that the shoulders are the widest part of the human body and that as they were the widest they would cause the most resistance.

He then decided to ride in a prone and not recumbent position due to this allowing a more streamlined shape for the cycle bodywork.

"A raindrop changes shape due to gravitational pull."

A rain drop falls because of gravitational pull it chances shape because of air resistance. If you put a water droplet in motion in a vacume it will not form a teardrop shape. For instance we've all seen the footage of astronought's spilling a liquid in a space that does not form a teardrop.

"liquid skins/fairing will work best."

Surely a liquid skin on a bike in forward motion will just allow all the fluid to flow to the rear assuming there is enough surface tension to keep it in one piece. It would form a pear shape widest end at the back due to wind resistance causing the fluid to move.

If you wanted a fluid skin the easiest way to control the shape would be to have an agent in the skin that was magnetic that would follow the lines of flux pre positioned around the bike from electromagnets that could be designed to form a predetermined teardrop shape from the position of the magnetic field .

There would be problems with this in that the skin would be very hard to control when the bike was in motion and would not have sufficient surface tension to stop it deforming in the wind.

It would also be too heavy for a bike as the power generation/magnets/batteries/solar panels would make it completely unviable due to size, weight and power consumption.

"I am still gobsmacked by Obree's find, because it is and will be proven to be, the turning point in cycling speed records, HIS theory/discovery is IMHO without a doubt groundbreaking. I'm sure there will be a huge outpouring from near & far that they did it first, but in truth, they got it wrong first Obree was 100% correct when they took the p*ss out of him all those years ago, and today he still does the same things, not to cheese people off, but because he simply looks for the answer to the question in his head = "how can I go faster (and live to tell the tale) ?" Later everyone, Laz."

I totally Agree with your closing statement and isn't it a refreshing change to have a person and a World Record that isn't constrained by Health and Safety, red tape or regulations that allow's enough freedom to truly invent where the only boundaries are your manufacturing skill and ability to think laterally.

Looking forward to your next post, John

 

[bikerjohn]

@paininthe

"It will not be the same horizontally when the length will have to be 8ft+ then balanced over the 2 wheels then removing the drag from the wheels and gaps around the wheels. The tear drop shape will have to balance the drag difference top and bottom. "

Completely agree, I think the finished shape would need to be more of a tapered Cigar than a teardrop something along the lines of below but with only smallest portion of the wheels protruding.

 

[gregs656]

sometimes life is easier than all that research, simply ask yourself what shape a raindrop is (teardrop) then ask yourself if nature knows best

Well, it sure as eggs is eggs isn't 'teardrop' shaped. They are spherical, then as they grow through collisions with other rain drops they are are shaped with flat bottoms and round tops, then when they break up due to resistance they go back into spheres.

I wish the man luck with his efforts, no doubt he is confident with his designs and I don't much suppose anything else matters until he gives it a go. Worst case he has to try again.

 

[rocky ridge]

theres a new video of grahams drive gear set up at
vimeo.com/44814746

hes running a 350" high gear

 

[Lazarus]

Hi again Some interesting stuff here, just like a good thread should be, lots of ideas and knowledge coming out.

The raindrop IMHO changes shape, it does not stay a complete sphere, in slow motion its change is visible. Why it changes shape is well known, and the reasons for its change are also well known, however the concept/theory that is not used in cycling is that the bulk of the weight on the machine is positioned to the front and not the rear. This is "propulsion" and not "drag". The point of the raindrop/teardrop shape is to ephasise that "it is heaviest at the front" and "self streamlines" to the rear. When I say "liquid fairings/skin" this is a euphemistic phrase to highlight the theory of less drag. In reality, a liquid skin would be a surface that allowed air to spill off it as though the skin where a liquid. It is a theory/concept not as yet a doeable reality (not that I'm aware of)

On another note, for all the diagrams about air / turbulence over cigar shapes, the idea as I understand Obree is " where inside this cigar do you place the bulk of the weight ?". All I know for certain is that a bullet is not dragged from the barrel of a gun it is propelled. A bullet is a similar shape to a cigar. Yeah sure it has fluting down the barrel to spin the bullet so it has less drag by cutting through the air, but the bullet does not leave the gun by being dragged out. It was this that caught my imagination, a fundamental change in how weight is carried on a bike.

I only know that in aero-dynamics you can either "avoid drag OR use drag as propulsion" If I add Obrees observation of "propulsion of weight" to "use of drag as propulsion" I have 2 of the main offenders now working For me not Against me. This change in direction re-writes ALL of the previous stuff because for all of the information out there it all relates to dragging weight around and avoiding as much drag as possible. I'm going to take a lot of convincing that its easier to just keep going down the same road knowing all along that "the currect theory is flawed". My simple brain tells me that "if my 2 worst enemies become my friends, friends that help all they can to their max, this has got to be better than designing ways to avoid them and counter act them when I do occur them".

I also know that if for example you drag backwards one of those toy thingies that has a spring loaded set of wheels, then let go, it moves forward, BUT, if you weight it down slightly more, it travels further under its own steam due to better traction. Maximum traction efficiency is governed by an increase in traction per increase in speed ie: rear wheel gravitationally pulling nearer to the road surface the faster you go. Traction does not always create drag, too little traction from the propelling end allows for the power of the proplusion to disipate/not get used to its max. Using all of this as a base for my thoughts caused me to draw that design. I know its hard to see from a simple diagram, but "a bike that funnels oncoming air into a channel that becomes proplusion at the rear + allows for the biggest cog ratios any bike can possibly have + gives maximum traction from power sources = the real equation to be solved. I am certain that the first bike that abides by those 3 rules will be the fastest cycle on earth. Any deviation from them will increase "ineffeciency".

X + Y + Z = fastest bike

X = Maximum conversion of oncoming air (Drag) into Propulsion
Y = Largest possible cog ratios that can be physically put & kept in motion by a human beings legs /body parts (Energy/Drving Force)
Z = Maximum Traction Efficiency from the Driving Force/Source of Propulsion

The only area I have left in my mind is "to design the flywheel". From what I remember, a fly wheel was a weighted wheel that helped itself via gravitational pull. Any wheel design that incorporates "help" from existing motion can only be beneficial to easing the burden on the cyclists legs. I'm also convinced after a lot of thought that using the drive wheel directly to power motion will give the maximum effeciency to drive the traction wheel, in essence, instead of pulling the motion I'll push it, which = propel & not drag motion. Still, all of this said, I'm not Graeme Obree, and I'm definately not wealthy enough to fund a build around my ideas, I am however moved enough by what Graeme said to sit and ponder & calculate theorems that at present are the opposite to what the current line of thought is I have been certainly caught by the bug to analyse the concept of Push not Pull. Later everyone, Laz.

PS: "totally Agree with your closing statement and isn't it a refreshing change to have a person and a World Record that isn't constrained by Health and Safety, red tape or regulations that allow's enough freedom to truly invent where the only boundaries are your manufacturing skill and ability to think laterally."

Ditto to this sentiment my friend I just love that his dream is now fueling my own thoughts. I do like a challenge from time to time Later John, Laz.

PPS: "Oh sorry, forgot to mention ... the term electro magnets does not mean magnets powered by electricity, I meant Super Charged Magnets, like those found inside computer hardrives ( I've got quite a few and their power is seriously amazing). They weight a few grams each, yet can grip each other through 2 inches of solid wood, they'll squash your finger tips and draw blood if you let them snatch with your fingers in the way. Point is : "put them in opposing poles 1 on the wheel, 1 on the stays and they will generate propulsion. On their own they do not amount to much, but if they reduce drag by 10 percent simply by offering 10 percent more free energy to the drive of the bike then the target of maximum use of drag > proplusion becomes easier to reach.

Total weight increase to the bike is circa 30 - 40 grams. A small price to pay for a 10 percent reduction of drag via extra free output. Also, the hubs can be lined with these magnets, ie: the spindles can be bearing free = counter-drag efficent to their max. Magnetic hubs will alllow the spindle to spin almost in perpetuity and reduce excessive forces on the hub itself. Magnets are wierd things, they don't always do what you'd expect They are not anti gravitational, but they come close to it

 

[bikerjohn]

Hi Lazarus, More interesting stuff

" where inside this cigar do you place the bulk of the weight ?"

I'm not aware if you've seen all 3 of Graeme's Video's on his bike design, but his original concept was derived from trying to find the most aerodynamic shape for a human body, not weight distribution. His reasoning was that as the Shoulders are the widest part of a body then it stands to reason that they must be at the front of the bike (against the recumbent position) as a shape that is wide at the front and tapers to the rear has a lower drag coefficiant than one that is narrow at the front and tapers to the rear (as in the recumberant riding position).

"drag backwards one of those toy thingies" etc

I'm confused by your traction theory, I agree completely that the car will travel further "if you weight it down slightly more" due to an increase in load causing less wheel spin via better traction.

However you go on to say

Maximum traction efficiency is governed by an increase in traction per increase in speed ie: rear wheel gravitationally pulling nearer to the road surface the faster you go. Traction does not always create drag, too little traction from the propelling end allows for the power of the propulsion to disipate/not get used to its max. Using all of this as a base for my thoughts caused me to draw that design."
"
Firstly to quantify my point I'm using the word traction is defined as follows

" the maximum frictional force that can be produced between surfaces without slipping"

To go on from this The coefficient of traction is defined as the usable force for traction divided by the weight on the running gear

therefore Usable Traction = coefficient of Traction x Weight

Your definition of traction uses "rear wheel gravitationally pulling nearer to the road surface the faster you go".

In the case of Graeme's bike. Gravity is a constant at ground level not variable. The static load (weight of rider+bike) is also a constant therefore the traction of the cycle does not change as long as the wheel does not spin through power in which case the torque (turning force of the rear wheel) has exceeded the maximum traction of the tyre).

I've also been doing some research your proposed design on page two that uses air flow to provide thrust over a wheel.

I'm assuming that your considering using air channeled through a venturi to increase air speed which will provide thrust.

According to the laws governing fluid dynamics, air velocity must increase as it passes through a constriction to satisfy the principle of continuity, also its pressure must also decrease to satisfy the principle of conservation of mechanical energy, Thus any gain in kinetic energy air may accrue due to its increased velocity through a constriction is negated by a drop in pressure it leaves the venturi.

Flywheels

"The only area I have left in my mind is "to design the flywheel". From what I remember, a fly wheel was a weighted wheel that helped itself via gravitational pull."

I'm again confused by your use of Gravity in a flywheel. If used in a Bicycle it would be fixed somewhere in the frame which would prevent its position from moving apart from rotation. As it is fixed in position Gravity has no effect on a flywheel.

A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia, and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed. Energy is transferred to a flywheel by applying torque to it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing its rotational speed.

The other problem with this is that the rules state that you cannot use due to rule

3.1.2 Energy Storage:" No device which stores energy over more than one input power cycle (e.g., one leg stroke)....
This means absolutely no chemical, electrical, kinetic, potential, or other form of energy storage at the start. This includes phase-change vests or ice packs"



P.s. If Anybody would like links to all the footage from Graeme I'll post them on here just let me know.

Right that's my two penny's worth for tonight, I look forward to the post's that follow, all the best, John

 

[Woz]

theres a new video of grahams drive gear set up at
vimeo.com/44814746

hes running a 350" high gear

The set-up did not make any sense to me. I suspected he was doing a test, since the bike was missing cranks where is feet would be, the chain had a cross-over point. WTF is that piston thing on a rear rack?

 

[rocky ridge]

yeah i must admit to being quite confused by the whole setup he had going on there
and quite concearned by how he was holding it right near the rear wheel spinning so fast
hes on a mission and hes got his way of doing things
the thing on the crank to the rear end god knows mate

 

[Lazarus]

Hi Woz, Rocky, John How's the weather out their in Sweden Woz ? Woz/Rocky ... " I think you'll find that he is playing with the theory of using drive-rods / pistons, like those used on old steam trains Good idea actually ...to within its limits ... until he reaches their max and realises their are more efficient ways to get the same output. I like his thinking though " a very practical I know how this works so lets use it, kind of thinking". Later chaps, Laz.

John : (I just made a huge post & the PC lost it on upload Grrrrr ! I'll get back to you buddy when I'm less angry :x ) We have much to discuss my friend I'll just edit this post when I'm ready. Later buddy Laz.

 

[bikerjohn]

Good to hear from you Laz, Glad I've posted something that makes you tick. I sometimes write the post in wordpad saving it as I go then copy and paste in into the forum box. Some of my post's take me two hours to write I know how maddening it is when they go blank on the screen. Looking forward to your next post though.

As for Graeme's drive system I'm assuming he's trying to overcome the wasted upstroke of a circular pedaling motion by using direct force in a vertical plain (to his body) I.e. pushing straight down at each stroke as it may produce more power per leg stroke. He may also be able to produce more pedal strokes per Minute if the return speed of each pedal is quicker than the time it takes to rotate a conventional crankset 360degrees..

John