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  1. #126
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    So, drum brakes? What kind of drive train are you using?

  2. #127
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    Quote Originally Posted by smilinsteve View Post
    Not parallel. Picture you draw a line from the COG to the rear axle, and from the COG to the front axle. So you have a triangle, with a line between the axles as the base. As you raise the COG (at the point of the triangle) the angle at the peak of the triangle gets smaller and smaller...

    You never get to parallel, but theoretically you can get that angle as close to zero as you want.

    Not that I think this exercise has any practical use. The difference in COG height is too minor in real bike design to be a player in the weight distribution problem. Like you said, its horizontal position that determines it in real life.
    The horizontal positions available is limited as you cannot move the COG outside of the wheelbase. Therefore the only way you way you can reduce the leverage effects of rear wheel torque reaction is by moving the COG upwards.

    The practical effects of this are indeed small. However, if you wanted to win a hill climbing competition at best it could increase the incline your bike could climb by the same proportion as the reduction in mechanical advantage caused by increasing the length of the 3rd angle lever. The distance between the rear axle and the COG.

    44% hill climb.
    Cleland: The original big wheeled off-road bicycle?-44_percent_climb_a_911.jpg
    Last edited by GrahamWallace; 09-27-2012 at 12:32 PM.

  3. #128
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    Quote Originally Posted by leeboh View Post
    So, drum brakes? What kind of drive train are you using?
    Back in the early 1980s, Cleland bicycles were fitted with Leleu 'floating cam' drum brakes. Apart from those made by Dave Wrath-Sharman, as far as we are aware, the Leleu brakes were the only floating cam drum brakes on the world market. All other drum brakes were, and are, fixed cam. This makes them unsuitable for extreme weather conditions and off-road use.
    The Leleu company in Lyons, France, closed down several years ago.
    Modern Cleland style bicycles use roller brakes. These are also in the hub and function completely differently to drum brakes. Roller brakes provide better modulation than disc brakes, they are cheap as chips, require virtually no maintenance (the pair I currently use are six years old and have had no more than 12 minutes maintenance in that period, and required no replacement parts). Moreover, they require grease to function and are thus completely impervious to water, so river crossings present no issues at all. The downside is that they are relatively heavy; with all those plus points, I'm quite happy to carry a few extra pounds.

    Pictorial details of the drivetain can be seen earlier in this thread. Further information can be found on the Cleland website. The drivetrain is fairly unusual, so as a general topic it is very broad. Once you have done your research, should you have any questions about specific areas, I'd be happy to respond.

  4. #129
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    Quote Originally Posted by GeoffApps View Post
    Back in the early 1980s, Cleland bicycles were fitted with Leleu 'floating cam' drum brakes. Apart from those made by Dave Wrath-Sharman, as far as we are aware, the Leleu brakes were the only floating cam drum brakes on the world market. All other drum brakes were, and are, fixed cam. This makes them unsuitable for extreme weather conditions and off-road use....
    I've used drum brakes and roller brakes offroad. A properly greased Shimano roller brake is much better than most people realise. I'd agree about the comments on the advantages of floating cam drum brakes, but Sturmey-Archer are now producing a 90mm drum which has more than adequate power (still not as powerful as a good disk though). However we're talking brakes that function longterm in foul conditions, and my experience is that disks don't do that without consuming expensive pads and needing maintenance.

    I've done 24 hour races in foul conditions with S-A drum brakes. I used them not because they are great brakes but because they were adequate brakes. Their great advantage is that in conditions where some competitors were changing their pads several times (as I had in earlier races) I was losing no time in the pits. When it's pitch black and the temp is around -10C I can take over 15 minutes an end to do what is usually a quick job. I reckon that was worth 1 lap overall, better than I could pick up by being fitter.

    This year's race was done on the larger S-A 90mm drums, which were much nicer to use because they didn't need the death grip to work on fast downhills. When stripped down after the race, there was negligible wear on the brake shoes and the internals were clean.

    This was one section before the race. It turned into mud soup and a brake grinder within the first lap.
    [IMG]

    Like this


    After the race. (The mudguards were to reduce the chance of hypothermia from being soaked more than to keep the mud off)
    [IMG]

    [IMG]

    Internal pics
    [IMG]



    Oh, btw, before I get pilloried for my unfashionable red bar ends in the wrong position, I'd better point out that they are so if I have to turn my bike upside down for trail repairs they will keep the bar off the ground and thus I don't have to remove my lights etc from the bars.
    Last edited by Velobike; 09-27-2012 at 04:00 PM.
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  5. #130
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    Quote Originally Posted by GrahamWallace View Post

    To repeat my original assertion:

    When riding up a steep slope you need to keep the weight over the rear wheel to maintain traction. But you also need to keep your weight over the front wheel in order to hold it down.

    But how can the weight be over both the front and back wheels at the same time?
    Theoretically it can if the weight is an infinite height above the bike.

    By the same logic a taller bike should be able to climb a steeper hill than a short one"

    This also explains why bikes with shorter wheel-bases climb best.

    Here is my explanation:

    The force that causes the front wheel to lift is an equal and opposite reaction to the torque being applied by the rotation of the rear wheel.

    In this instance a bike can be considered to be a third class lever with its pivot at the center of the rear axle, the input effort is the torque reaction from the rotation of the rear wheel as applied at the outside of the axle, and the load being the riders weight levered is at the COG.
    Bear in mind that with a third class lever the input force is always larger than the force applied to its load. Therefore, the further away the COG from the rear axle the smaller the reaction force applied to the COG. And at an infinite distance the force applied at the COG would be zero. In order for the bicycle not to tip forwards or backwards the COG needs to remain within the wheelbase so the only place it can be located at infinity is above the bike.

    Of course in reality you can't locate the COG at infinity. Even if you could its inertia would cause the bike to tip backwards as the bike went forwards. However moving the COG as far away from the rear axle whilst keeping it within the wheel-base will reduce the magnitude of the torque reaction. The best place to put the COM is high above the front wheel. Remember that the front wheel is further up the hill than the rear wheel so the wheel-base will have shortened relative to the horizontal. Due to the inertia of the COG any acceleration force applied to the will increase rear wheel traction but can also cause the bike to tip backwards. So smooth pedaling is essential. This can be aided by the use of elliptical gears that also allow the cadence to be lowered whilst reducing the chances of rear wheel slip.
    I am not seeing this at all.

    Third class lever? that would mean the force is in between the load and fulcrum. If the load is the COG and the fulcrum is the axle, what is the force and where is it applied? You say:

    the input effort is the torque reaction from the rotation of the rear wheel as applied at the outside of the axle
    Well, the axle is attached to the bike by freely rotating ball bearings so there is no torque transfered from the wheel to the axle or the axle to the frame.

    The ground force creates a force reaction, not a torque, at the rear axle pushing the bike forward.

    So the force is at the fulcrum, and if the force is at the fulcrum it creates no rotation around the fulcrum.

    So what makes the front wheel lift?

    In a climb, like in that 44% grade picture, the only contact points of the rider to the bike are at the handlebar and at the pedals. If the bike and rider are at equilibrium with both tires on the ground, then you can raise that COG to infinity (along the force vector) without effecting that equilibrium.

    Now, suddenly the front wheel comes up, so one of these things must have happened.
    1. An upward force from the ground (bump).
    2. A rearward weightshift such as caused by acceleration from a pedal stroke.
    3. Pulling up on the handlebars.

    That's all I can think of. And height of the COG doesn't effect any of them unless changing the height also changes the for/aft weight distribution.

  6. #131
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    Quote Originally Posted by meltingfeather View Post

    As the height of the COG increases, so does the rider's need to move his position relative to the axles to account for it. Thus, height will at some point limit the grade that can be climbed without the bike tipping.
    Your above statement is true if the COG is being accelerated by drive forces emanating from the rear wheel. It would not be true if the COG is moving at a constant velocity.

    Of course with a low frequency pulsed drive of a bicycle some acceleration and deceleration of the COG is inevitable. So keeping the drive smooth as possible is essential. Hence the use of elliptical gear rings. It is only the reaction forces to any acceleration that can cause the front wheel to lift. The question is where to best position the COG in order that its weight can best counter these reaction forces.

    Remember that to move it forwards will reduce the traction of the rear wheel.

    And to move it backwards will of itself, will reduce the leverage that the COG has over the reaction forces.

    To move the COG upwards along the diagonal axis between the rear axle and the COG will increase the leverage that the COG has over the rear wheel torque reaction. Whilst the reaction force due to COG inertia, remains unchanged.

  7. #132
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    Quote Originally Posted by GrahamWallace View Post
    ...Of course with a low frequency pulsed drive of a bicycle some acceleration and deceleration of the COG is inevitable. So keeping the drive smooth as possible is essential. Hence the use of elliptical gear rings. It is only the reaction forces to any acceleration that can cause the front wheel to lift. The question is where to best position the COG in order that its weight can best counter these reaction forces...
    I hadn't thought of that advantage of using elliptical rings. On really rocky steep hills, I've usually found the inability to keep the front wheel down stops me more often than the loss of puff or traction. I'll have to give it a try and see if it works for me.

    Edit: just been to HIghpath site, not currently available. Anywhere you recommend for these?
    Last edited by Velobike; 09-27-2012 at 05:45 PM.
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  8. #133
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    Quote Originally Posted by GrahamWallace View Post
    Your above statement is true if the COG is being accelerated by drive forces emanating from the rear wheel. It would not be true if the COG is moving at a constant velocity.
    It is true even if moving at constant velocity. The comment is specifically in regard to a bike on grade. At some point the bike will tip due to the grade moving the COG rearward of the rear axle, even if standing still. Increasing the grade as well as raising the COG make tipping due to acceleration easier.
    Quote Originally Posted by GrahamWallace View Post
    The question is where to best position the COG in order that its weight can best counter these reaction forces.

    Remember that to move it forwards will reduce the traction of the rear wheel.

    And to move it backwards will of itself, will reduce the leverage that the COG has over the reaction forces.

    To move the COG upwards along the diagonal axis between the rear axle and the COG will increase the leverage that the COG has over the rear wheel torque reaction. Whilst the reaction force due to COG inertia, remains unchanged.
    Well put, and exactly my point. Without the forward movement, raising the COG is counter productive to weight distribution on a bike on a grade.
    Last edited by meltingfeather; 09-27-2012 at 06:20 PM.
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  9. #134
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    Quote Originally Posted by NEPMTBA View Post
    And why not Horses?

    They graze as they go, water at any stream, can carry more gear, and are faster...LOL
    An Army commander was very influential for the start-up of bicycle mounted soldiers, had lots of pull! Not only that, bicycle mounted troops were popular all over Europe and Africa for many years. The Swiss were very much involved and still are to a degree.

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  10. #135
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    Quote Originally Posted by meltingfeather View Post
    Parallel lines do no get closer together (what would be required for even weight distribution) no matter how long you make them. Also, for weight distribution, the horizontal distance from COG to axle is relevant. Height of the COG is irrelevant, unless I'm missing something.
    I have rethought what I wrote earlier, and agree that the height of the COG is irrelevant to the weight distribution.
    And I would appreciate it, Melting Feather, if you would slap my silly as$ back into place when I say stupid crap

    The COG can be represented by a point and it creates a force vector directed from that point to the center of the earth. That vector is on a line that goes up into space and no matter where you move the COG up that line, the force vector to the ground does not change, so the weight distribution doesn't change.

  11. #136
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    I have a really short top-tube, short wheelbase bike with an oval chainring. I agree with Geoff and Graham re climbing balance. Also on the trails-style handling benefit of a higher COG, a taller front end and more upright position puts me higher on teh bike when stood up and it has real benefits on slow, technical terrain comaperd to conventional bike design. Personally I prefer the way a low-BB bike can corner at speed and the planted feel it gives on a steep descent, but bikes are all about trade-offs and compromises - often the bikes that don't need to be too compromised are the best for some riders. Depends on how / what you ride.

    BTW, I've ridden that slope pictured earlier as I live + ride in the same area. It's steep, but not at-the-limit crazy-steep imo. It's long, uneven and traction is low though, so as a test of control it's a good one!

    Always interesting to read about these bikes, so thanks to Geoff and Graham for sharing your take on bike design. I think it's only the fact that common MTB culture has taken the direction it has that has made this style of bike marginal in its appeal, since the theory and 'riding ideal' that it's based on is excellent.

  12. #137
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    Maybe see you at the Birthday Ride this December?

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    New question here.

    Here is the problem in diagrammatic form.
    Cleland: The original big wheeled off-road bicycle?-torque-reaction.jpg

    The vertical broken line represents the center of the wheelbase.

    The red arrow represents the rear wheel torque but is not shown to scale. (If shown to scale is would be more than twice the size of longest reaction force shown).

    I have used black dots to represent three differently placed COGs, Attached an arrow to each black dot that shows the direction and relative magnitude of the torque reaction acting at each COG. (The top COG though not achievable on a standard bicycle is nonetheless, theoretically interesting).

    Each dotted line connecting the rear wheel to a COG represents the central axis of a virtual third class lever that transmits the anti clockwise torque reaction forces. In reality these forces would be transmitted through the bike and the body of the rider. (Remember that with a third class lever, the longer the lever, the less force is transmitted to the COG).

    Not shown is:
    * the large gravitational force acting vertically downwards on each COG.
    * the drive forces that act upwards and forwards from the rear axle to each COG.( These forces act as an equal and opposite reaction to the rear wheel torque They push the COG both onwards and upwards).
    * the reaction forces that would be generated by sudden accelerations of the COG caused by pedaling that is not smooth, (these will act at the GOG in equal and opposite direction and magnitude to any acceleration or deceleration).

    But what COG position will allow you to climb the steepest hill?

    If your not confused by now you're not trying hard enough

    Missing info: is the mass of the bike and rider and the coefficient of friction of the rear tire.
    Last edited by GrahamWallace; 09-28-2012 at 11:33 AM.

  14. #139
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    Maybe see you at the Birthday Ride this December?
    The Wendover ride? Would love to, thanks.

    edit to add, Graham doesn't do a lecture in the pub after does he..? Just kidding. Keep at it and I'll keep reading.

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    That's a nice drawing Graham.
    I still don't think we are on the same page.
    I do appreciate discussing it with you.

    What I'm thinking.

    - The red line is not a torque, it is the force vector caused by the tire pushing on the ground, and the equal and opposite vector is acting at the rear axle pushing the bike forward.

    - There is no "torque reaction" at each COG. The only forces on this system are red arrow, the forward force reaction at the rear axle, the downward force from the weight of the bike and rider, and the normal force up from the ground on the tires that is countering the weight.

    - When the bike accelerates from the red arrow force, if the bike and rider act as 1 rigid body, the position of the COG doesn't effect the motion. The only thing that matters is that the COG is in a place to provide sufficient force on the tires for traction in the rear and for stability of the front.

    -Normally, the bike and rider do not act as one rigid body. Acceleration will cause the bike to squirt out from under the rider, causing a relative weight shift backwards (the inertia of the rider is greater than that of the bike). A higher COG potentially makes this worse because the there is a longer lever arm from the COG to where the force is applied to the rider (his feet and hands if he is standing on the pedals).

    - In your picture, the answer to your question "which COG position will allow you to climb the steepest hill?" the answer is the most forward one if front wheel lift is the limiting factor, but in general it is the one that gives you the right balance of rear traction and front stability. This is detemined by the for-aft position of the COG only. I don't see how the height makes any difference at all.

    - I still see nothing analagous to a class 3 lever, since I disagree that there is a force (or "torque reaction") at the COG that you have drawn.

  16. #141
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    Quote Originally Posted by GrahamWallace View Post
    Remember that with a third class lever, the longer the lever, the less force is transmitted to the COG.
    This argument has a converse that equally and oppositely counters it.
    As you move the COG away from the axle you also decrease the force/inertia effect required to impart torque/rotation about the axle by increasing the lever arm (the same mechanism by which the torque reaction is being reduced).
    In your own example of COG at infinity, when the "force transmitted to the COG," as you like to put it, is zero, the bike tips upon first input, which is not an equalization of weight distribution as you claimed, but the opposite extreme. The basic 3rd class lever example falls short in that, on a bicycle, the pivot point is free to move, and so, with a COG at infinity, no motion or force input at the COG is required for the relative rotation of the COG about the axle, which occurs due to movement of the pivot point, and the net effect is movement of the COG behind the rear axle (and tipping).

    Heightening the COG exacerbates the weight distribution effects of acceleration and grade.
    As you move the COG forward you balance and counter the effects of both forward acceleration and grade.

    I think that the raising of COG, which you are making as an argument for effective hill climbing, is nothing but a side-effect of moving forward, which on a bicycle requires standing.
    Quote Originally Posted by GrahamWallace View Post
    If your not confused by now you're not trying hard enough
    Interesting dialogue, to be sure.
    You Brits certainly are masters of adverse conditions riding. The terrain around here gets destroyed if ridden in those conditions and if I posted a photo of riding local terrain in that condition I'd get tarred and feathered by any local mtb'ers that came across it.
    Not to mention our climate can be described as long periods of drought punctuated by brief interludes of flash flooding.
    Last edited by meltingfeather; 09-28-2012 at 02:11 PM.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  17. #142
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    Quote Originally Posted by smilinsteve View Post
    That's a nice drawing Graham.
    I still don't think we are on the same page.
    I do appreciate discussing it with you.
    We may not be "on the same page" but are both seekers of the same truth.

    Steve you make some valid and interesting points there. However, before I reply in detail I would like to clarify whether you believe that torque reaction forces are involved at all?

    Here's a video of a Segway driving up and down a steep slope. Note the Segway is moving at a constant velocity and is not accelerating. However the rider can be seen to lean forwards markedly. Why does she need to do this and why does she not fall forward. Does it make sense that a faster rider or a shorter rider of the same weight would need to lean forwards even more?
    Steep segway climb - YouTube

    There is clearly some leverage involved in stopping the rider from falling forwards.. Could this leverage be categorized as the class three? And could the leverage result from the torque reaction to the motor/gearbox?

    Why doesn't the rider need to lean when going downwards?

    Ideally we need some good footage of a unicyclist riding up a steep slope, but so far, I haven't found a good example.


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    Quote Originally Posted by meltingfeather View Post
    This argument has a converse that equally and oppositely counters it.
    The end game here is to arrive at some kind of consensus that we can agree on.
    There is no value in me having a theory if it won't stand up to scrutiny.

    We are treading new ground here, I don't know of any discussion of this topic in the "bicycle science" textbooks or Wikipedia.
    Take a look at the Segway clip that I have posted, what do you think?.

    My I ideas are based on testing various bike designs on my local 44% hill and then coming up with a rational of my own for what I have found. I have also built radio controlled models to test out ideas. I am hoping that what I learn from this conversation may feed into future bike designs.

    I will carefully consider your and Steve's thoughts and then report back in detail.

  19. #144
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    I'm reminded of a purported quote from a former Australian Prime Minister:

    "That may work in practise, but it doesn't fit my theory" or words to that effect.

    The theories here all make sense in themselves, but the QED here is that Graham is climbing these hills when most can't. Finding out whether that is because he has monster legs and an incredibly smooth technique, or because of the bike design is the fun part.
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  20. #145
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    Quote Originally Posted by GrahamWallace View Post
    We may not be "on the same page" but are both seekers of the same truth.

    Steve you make some valid and interesting points there. However, before I reply in detail I would like to clarify whether you believe that torque reaction forces are involved at all?

    Here's a video of a Segway driving up and down a steep slope. Note the Segway is moving at a constant velocity and is not accelerating. However the rider can be seen to lean forwards markedly. Why does she need to do this and why does she not fall forward. Does it make sense that a faster rider or a shorter rider of the same weight would need to lean forwards even more?
    Steep segway climb - YouTube

    There is clearly some leverage involved in stopping the rider from falling forwards.. Could this leverage be categorized as the class three? And could the leverage result from the torque reaction to the motor/gearbox?

    Why doesn't the rider need to lean when going downwards?

    Ideally we need some good footage of a unicyclist riding up a steep slope, but so far, I haven't found a good example.

    Graham you are really making me do my homework! I don't know anything about Segways, but now you give me something else to figure out.
    That's ok. I've been involved in these physics discussions in this forum for a couple of years (and have bumped into Melting Feather in a few of them), and I think I have learned more about physics at MTBR then I ever did in college (or close anyway).
    I will get back to you on this. I hope however, that I have enough fun, and a good ride, this weekend, that will keep me from spending too much time on the computer.

  21. #146
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    Quote Originally Posted by GrahamWallace View Post
    Here is the problem in diagrammatic form.
    Click image for larger version. 

Name:	Torque Reaction.jpg 
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    > SNIP <

    But what COG position will allow you to climb the steepest hill?

    If your not confused by now you're not trying hard enough



    > When the tyres loose contact! When this happens you will also be in a controlled or uncontrolled crash! <

    Missing info: is the mass of the bike and rider and the coefficient of friction of the rear tire.
    Some sort of "zero-sum-game" one plays with gravity.... the bike becomes a tool to win and the better you know your "tool", the greater your "edge"!

    poikaa
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    Quote Originally Posted by smilinsteve View Post
    Graham you are really making me do my homework! I don't know anything about Segways, but now you give me something else to figure out.
    Here's an explanation of Segway technology from Wikipedia:

    "The dynamics of the Segway PT are similar to a classic control problem, the inverted pendulum. The Segway PT (PT is an initialism for personal transporter while the old suffix HT was an initialism for human transporter) has electric motors powered by Valence Technology phosphate-based lithium-ion batteries which can be charged from household current. It balances with the help of dual computers running proprietary software, two tilt sensors, and five gyroscopic sensors developed by BAE Systems' Advanced Technology Centre[5]. The servo drive motors rotate the wheels forwards or backwards as needed for balance or propulsion. The rider controls forward and backward movement by leaning the Segway relative to the combined center of mass of the rider and Segway, by holding the control bar closer to or farther from their body. The Segway detects the change in the balance point, and adjusts the speed at which it is balancing the rider accordingly. On older models, steering is controlled by a twist grip on the left handlebar, which simply varies the speeds between the two motors, rotating the Segway PT (a decrease in the speed of the left wheel would turn the Segway PT to the left). Newer models enable the use of tilting the handle bar to steer"
    Segway PT - Wikipedia, the free encyclopedia

    The best example a "torque reaction"/third class lever machine, that I know of, is the classic dragster design. The long front end being one big reaction arm to the rear wheel torque..
    Name:  vintage-dragster-artwork.jpg
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    The COG of the dragsters engine is directly ahead of the rear axle so as to eliminate the chance of the engines inertia lifting up the nose and then flipping the dragster backwards. But in order to gain the maximum rear wheel traction the COG of the dragster needs to be as close to the rear axle as possible. The problem is that the torque reaction is powerful enough on its own, to lift the engine and flip the dragster backwards. To solve this problem by adding a large extra forward weight, would only serve to slow down the dragster. And moving the engine further forward, away from the axle, would reduce rear wheel traction.

    So instead they add a long and lightweight third class lever reaction arm onto the front. By placing a small weight at the nose end of this arm will then create enough down-force to counter the torque reaction. This works in the same way that a weight in an outstretched arm feels heavier than the same weight when your arm is bent.

    One thing to note regarding the video of the hill climbing Segway is that no bicycle under its own power, could ever ride up a slope that steep. The rear wheel torque of a bicycle would be nowhere near smooth enough. To make big inroads into the maximum incline that can be ridden on a bicycle, the problem of the pulsed nature of rear wheel torque would need to be addressed.

  23. #148
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    Quote Originally Posted by Poikaa View Post
    Some sort of "zero-sum-game" one plays with gravity.... the bike becomes a tool to win and the better you know your "tool", the greater your "edge"!

    poikaa
    For me, riding up challenging hills is inexplicably compulsive.
    Though I have never been interested in racing on mountain bikes I love to take on and hopefully defeat hills. It's part of my psyche, Like riding in bad weather. I seem to be more interested in defeating nature than other people. It's a form of insanity' It's very hard work and these hills would be easier and quicker to conquer on foot. And most of my climbs are attempted when no one is watching to see me either succeed or fail. I guess it's good exorcise and less dangerous than most other things that people do on mountain bikes.

    I do however recommend that people who try this practice ways of getting off quickly when things go wrong. As not knowing how to react when the rear wheel suddenly spins out on a 44% slope could result in you returning down the hill head first, with the bike landing on top of you. I am now equally as good at bailing out, as I am as getting into trouble in the first place.

  24. #149
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    Quote Originally Posted by Velobike View Post
    "That may work in practise, but it doesn't fit my theory" or words to that effect.

    The theories here all make sense in themselves, but the QED here is that Graham is climbing these hills when most can't. Finding out whether that is because he has monster legs and an incredibly smooth technique, or because of the bike design is the fun part.
    I know which of my bikes can climb my 44% test slope and I know those that can't. I even keep information of the relative success rates of the good climbers. The problem is that all my 5 bikes are different.In order to identify exactly what made then climb better I would have to change one parameter at a time and then test the slightly altered bikes in identical conditions. I would also need to repeat the rides many times and record and average out the runs to take account of variations in the exact path taken.

    Though I am mad enough to do all this, in reality I neither have the time or the money.

    In mountain biking like many other sports the main driver for innovation is racing. The fact that we don't have a category of 'Uphill Racing' means that very little effort has gone into improving the climbing characteristics of mountain bikes.
    Last edited by GrahamWallace; 09-30-2012 at 04:09 AM.

  25. #150
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    Quote Originally Posted by GrahamWallace View Post
    The end game here is to arrive at some kind of consensus that we can agree on.
    There is no value in me having a theory if it won't stand up to scrutiny.

    We are treading new ground here, I don't know of any discussion of this topic in the "bicycle science" textbooks or Wikipedia.
    Take a look at the Segway clip that I have posted, what do you think?.

    My I ideas are based on testing various bike designs on my local 44% hill and then coming up with a rational of my own for what I have found. I have also built radio controlled models to test out ideas. I am hoping that what I learn from this conversation may feed into future bike designs.

    I will carefully consider your and Steve's thoughts and then report back in detail.
    This is an interesting discussion, and certainly something I need to think more about; I will.
    The Segway context is something i need to digest a bit.
    The dragster example has a couple of key differences: weight as a critical design driver being primary.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

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