Unigeezer did you go downhill on that street in LA?
Leaning
Obviously when you on on a sloped surface the part of the tire that comes in contact with the ground will be before the axle if you are riding uphill or behind the axle if you are riding downhill. This is because the tire can’t flex like an ankle can when you are on a skimulator. This does not change the fact that you if you put a skewer through your head that comes out your bottom it will be pointing to the center of the earth. A person standing on one of the poles is perpendicular to a person standing on the equator. Put the person standing o the equator on a slope and his ankles will be flexed at an angle but he will still be perpendicular to the person standing on the pole be ir North or South.
Think of this theoretical example. If you had a super sticky unicycle tire that would allow you to climb a cliff or a wall with the Uni the front of the tire would be making contact with the cliff or wall and your body would be parallel to the wall. Are you leaning away from the earths core?
You assert this, but I don’t think it’s true. For one thing, it’s possible to ride a recumbent unicycle, or a unicycle with a long handle that makes you lean way over; in either case your head and butt are not orthogonal to the center of the earth.
And in any case, I don’t think your axis of gravity on a moving unicycle is orthogonal to the center of the earth. Consider an idling unicycle; when you idle, you are pivoting around your center of gravity, so your axis goes from pointing forward of the center of the earth to pointing rearward.
I assert that it is impossible to ride a unicycle forwards or backwards when your balance axis is perfectly orthogonal. Think about hopping; if you are hopping in one place, your axis of balance is more or less orthogonal. Now if you decide you want to ride forwards, you must lean forwards, tilting your axis of balance, and then as you begin to fall forward, you pedal to keep the unicycle under you. Unicycling forward is the act of keeping your balance axis slightly ahead of orthogonal.
A person lying down on one of the poles is not perpendicular to a person lying down on the equator. Nor is a person riding a bicycle, nor a unicycle.
As with any unicycle riding, if you are moving forward, your center of gravity is somewhat ahead of your contact patch with the ground. This is one reason you can’t ride up a cliff.
It so happens that one of the top 10 publications of the Royal Society in 2010 was a highly technical examination of unicycle path prediction. (unicyclist.com even gets a mention!)
See: Robin S. Sharp, “On the stability and control of unicycles”, Proc. R. Soc. A June 8, 2010 466:1849-1869; published online before print January 20, 2010, doi:10.1098/rspa.2009.0559
Sharp models the ridden unicycle as having three parts; wheel, frame+lower body, and upper body, with the rider’s waist acting as a spherical joint (so the upper and lower bodies move independently). See especially figure 11, where it is shown that the upper body and the frame movements in a turn are inversely related. It is not possible for the upper body to remain orthogonal while this manoeuver is performed; when making a left turn, the body leans to the left while the unicycle goes to the right, and the opposite happens when making a right turn. (The paper demonstrates a lane-change manoeuver.)
Thanks for that link. Now I have something to hand out when someone asks, “How do you ride that?”
Addressed to Tholub
Jumping and turning are momentary activites that must be corrected if you want to continue riding. I don’t see anyone maintaining a jump for over an hour!
Notice that I wrote “standing” at the pole and equator. A person laying at the equatore with his feet and head pointed at the poles would be parallel to a person standing on one of the poles.
With recumbent and handlebared unicycles you are correct with my skewer analogy being wrong but they are probably less than a fraction of one percent of the unicycles. Even with those exceptions if you skewered the person (probably through the abdomen.) while he was riding on a flat plane so that the skewer was pointing towards the center of the earth the skewer would still point to the center of the earth when riding uphill or downhill.
When idling you must brake forward or backwards or else you will find yourself on your face or on your ass on the ground!
So is riding forward. If you need to have this demonstrated, ride forwards and take your feet off the pedals.
You keep asserting it, but you’ve provided no proof, and there’s basically no possible way the physics could work the way you suggest. Your center of gravity must be forward of your balance point to move forward, which means that your axis of balance is sloped relative to the orthogonal axis.
Off The Point
When accelerating riders are going to lean when decelerating riders are going to lean Tholub allready mentioned turning and jumping. Im sure that that with pirurettes, crank flips, granding and all sorts of other activites riders lean in one direction or another. All these examples are way off the point here. When riding up a hill the angle of your body in relation to the earths center shoud not change.
Unicorn
Today I learnt the word orthoganol.
Now that my vocabulary has been enhanced, what I really like to learn is how to ride up hills on my unicycle.
I’ve got a pretty good idea the answer is - practice.
So new is the word that I have not learnt how to spell it correctly.
Can we have some more hill climbing videos please - for those of us wanting to do and not theorise they’re worth a thousand new words.
I’ve presented photographic evidence. I’ve presented scientific evidence. You’ll have to do more than assert your position again.
What does it mean? It sounds like a drug 
The only way to ride a unicycle forward is to lean forward enough so that you start to tip forward. You then pedal with enough force to bring the wheel under you. To slow down you lean backwards so that with no other action you will eventually fall back. You then apply force to the pedals to decelerate, and that brings the wheel under you. To continue riding forward at a steady pace you need your center of gravity slightly in front of the wheel, and you pedal to catch up. All of these effects are much more obvious to the user on a larger wheel (or on a giraffe.)
Walking is a similar action: you lean forward so that you start to fall forward. You then take a step to convert you unbalanced position into forward locomotion. I have used this analogy to help people understand what they are trying to do when riding a unicycle.
Scott
First of all, excuses are just that, excuses. Given that, though, I hadn’t ridden in months EXCEPT I’d just done a pretty hard climb (Doheny) the day before, which left me nice and sore in the quads. By the time I was half-way up Fargo, my thighs had had enough. I couldn’t relax enough to keep pedaling.
Leaning on Hill Climbs
Tholub you are agruing a different point. I didn’t say that when riding
a person doesn’t lean. What I wrote was that when a person rides uphill or downhill for that matter he will not lean any more than when riding on a flat surface. It is the ground that is angling up towards or away from the rider not the rider who is leaning into the ground. And I am restating it here if it was misconstrued.
If I am riding a unicycle on a skimulator the angle of my body in relation to the earth’s center is not going to change as the skimulator surface tilts. As the surface tilts it will come into contact with different parts of my tires either forward of the axle or behind the axle but my body position will stay the same. (Unless I am accelerating or decelerating.)
The attached picture should demonstrate that we are not actually leaning more when we ride uphill than when we are riding on level ground. It is an illusion becouse when we are riding uphill the ground is much closer to our face.
Hi Unicorn,
Nice Drawing!
I would suggest that in order to move forward the unicyclist must have his or her center of gravity just in front of the contact point between the wheel and the ground. For the figure on the left the probably means leaning slightly forward. For the figure on the right the point of contact between the wheel and the ground is in front of the rider. The rider would thus need to lean forward enough to bring the center of gravity just in front of the wheel contact point. As drawn, the unicyclist would fall down backwards.
Data:
Here is Terry’s Fargo street ride. Look at the angle he is leaning to get up the hill. To me it appears that his head and torso are in front of the wheel, rather than straight up as depicted in your drawing. (For example, 38 seconds in he passes a telephone pole, and his head passes the pole before his tire gets to it.)
Scott
Leaning
Scott thanks for your input.
I am not saying that people don’t lean when they ride. I appologize if I gave this impression. I am saying that the slope of the ground does not make a person lean more or less. I realize that when a person is accelerating or decelerating he is going to lean somewhat.
Concerning Terry’s video stand a book flush on the table and notice that Tery is pretty close to parallel with the book edge. Now yes his head and shoulders do lean forward past the edge of the book but his hips counter this by being behind the book edge. Some riders do like to bring thier hips farther back and this must be countered by bringing the shoulders forward. (Riding in a more crouched less strait position allows for better dealing with obstacles. It does not however change the center of gravity.) Now if you compare the street in Terry’s video with the book I think that you will find the agle created to be about 57 degrees. That is if the slope of the street is 33 degrees as Terry states.
I originally postied in this thread because it is just plain wrong to make begginers think that they have to lean way forward in order to climb hills. If you do lean farther forward when hill climbing your tire is going to loose traction, spin out and you will fall forward.
Unicorn
Common mistake. It’s 33% grade, not 33 degrees. And I don’t conscientiously think about leaning forward, backward, whatever. Your body will naturally find the CG and the best/most efficient upper body position, depending on the type of riding you’re doing. At least that has been my experience.
Percent vs Degrees
Interesting - Does a 33% grade mean a 30 degree slope?
It takes practice for begginers to get the correct technik. It helps if they understand and can visualize what they have to do.
Unicorn