Riding an inverted bike - Page 1
Forum section: electronics / general

author: zapta
author_rank: Super Contributor
timestamp: April 28, 2015, 03:52:58 pm
content: It's not as simple as you may think.

author: electr_peter
author_rank: Unknown
timestamp: April 28, 2015, 05:45:12 pm
content: I have seen such bikes in carnivals - almost impossible to ride few meters straight.To me this is not surprising. In many ways this is similar to writing with pen, typing a keyboard, throwing a ball, playing piano or other musical instrument, flying RC helicopter, etc. In all these cases you are not actually doing it, you are just repeating some muscle memory with slight adjustments.Throw in some unexpected condition -> muscle memory fails -> now you have to think about all actions -> you are too slow -> massive fail.

author: mtdoc
author_rank: Super Contributor
timestamp: April 28, 2015, 06:16:07 pm
content: Cool video.I agree it is not surprising at all though. He uses terms like "thinking", "knowledge" and "cognition" but those things have nothing to do with it.Riding a bike, or any such highly coordinated motor activity (walking being the prime example) depends on synaptic/neuronal development ("learning") at the spinal cord, brainstem and cerebellar level - completely independent of any higher brain functioning. Part of it is simply an issue of latency - the time to transmit info from proprioceptors in muscles and joints --> spinal cord -->brainstem-->etc and back down to muscles. With multiple iterations needed for even simple coordinated movements. This kind of lower level motor learning ("muscle memory" in popular terms) is relatively hard wired once it occurs.As you could see he did not really modify the old pathways so much as form new ones for a related but actually 180 degrees out of phase task.His son- being at the age where the nervous system is primed for motor learning (and still able to make new neurons easily)- was able learn this new task quite quickly.Younger nervous systems are much more plastic - especially at the lower levels. Higher level plasticity at the cerebral cortex level - remains intact for much longer.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 28, 2015, 09:48:54 pm
content: I'm cross-dominant (a few steps below ambidextrous) and can play a trumpet with either hand or a right handed guitar in a left handed "stance", but can not for the life of me play a left handed guitar. And it's sooo frustrating trying. I've a feeling this is sort of the same thing.Quote from: mtdoc on April 28, 2015, 06:16:07 pmSynapses, not neurons.

author: mtdoc
author_rank: Super Contributor
timestamp: April 28, 2015, 10:03:55 pm
content: Quote from: Mechanical Menace on April 28, 2015, 09:48:54 pmActually young children's brains and spinal cords are making new neurons as well. There is some limited ability in adults to make new neurons but it is confined to a few small areas of the brain.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 28, 2015, 10:10:26 pm
content: Quote from: mtdoc on April 28, 2015, 10:03:55 pmYeah, but it's the synapses that help with learning after you gain a critical mass of neurons. In fact "pruning" synapses and putting a massive amount of neurons into "standbye" mode during the crazy teenage stage actually counter intuitively ups our cognitive abilities and straight up processing power quite a bit.If you keep in the habit of learning you can still easily learn new skills too. If you don't keep in the habit it takes longer but after you've done it once...

author: mtdoc
author_rank: Super Contributor
timestamp: April 28, 2015, 10:20:47 pm
content: Quote from: Mechanical Menace on April 28, 2015, 10:10:26 pmI agree. The point I was trying to make earlier is that young children's central nervous systems have greater plasticity than adults and have specific "critical periods" for development of certain skills (eg motor skills). In addition to synaptogenesis, part of this process involves neurogenesis in the spinal cord and brainstem that adults are incapable of.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 28, 2015, 10:29:49 pm
content: Quote from: mtdoc on April 28, 2015, 10:20:47 pmI'd disagree that's what the limiting factor here is though. I'd say this is more case of remapping the control of those motor skills, like my case with playing a left handed guitar, rather than learning a new motor skill.And I'm not sure if that really makes any sense lol.

author: mtdoc
author_rank: Super Contributor
timestamp: April 28, 2015, 10:59:40 pm
content: Quote from: Mechanical Menace on April 28, 2015, 10:29:49 pmWell, you aren't disagreeing with me! I don't think anyone knows what the rate limiting step is, only a general understanding of the processes involved.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 28, 2015, 11:16:09 pm
content: The only way to do it is ignore the handlebars entirely and ride hands-free. I saw some guy hop on, grab the back of the seat with both hands and he just moved in a straight line. Fringe Festival in Montreal.

author: miguelvp
author_rank: Super Contributor
timestamp: April 28, 2015, 11:25:38 pm
content: I agree with Alex, when I just saw the video I was thinking to myself, why don't they just ride it without using the handle bars? I can't be the only one that knows how to do that.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 28, 2015, 11:28:20 pm
content: Quote from: miguelvp on April 28, 2015, 11:25:38 pmTry riding those first few feet without using the handlebars...

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 29, 2015, 12:35:25 am
content: Quote from: Mechanical Menace on April 28, 2015, 11:28:20 pmI'll ask the guy how he does it if he's in the Fringe this year.

author: Lightages
author_rank: Unknown
timestamp: April 29, 2015, 12:59:23 am
content: This kind of thing illustrates how people can get locked into a belief and not be able to think differently, perhaps. Maybe it is a bit of a stretch to connect a physical coordination algorithm with conceptual and abstract processes, but maybe there is some kind of relationship.

author: Smokey
author_rank: Super Contributor
timestamp: April 29, 2015, 01:24:40 am
content: I REALLY want one of these bikes to play with. Makes me want to learn how to weld. I like to think I'm pretty good at these "mental control system" problems.

author: mtdoc
author_rank: Super Contributor
timestamp: April 29, 2015, 02:59:18 am
content: Quote from: Smokey on April 29, 2015, 01:24:40 amBut it's not a mental control issue. "Mental control" implies a much higher level of abstraction (executive function in neuro-cognitive speak) It would be like some one saying they could control machine code level computer I/O because they are pretty good at scripting in Windows.I know it seems like it should be just a matter of "mind over matter" to be able to ride it - but just as the video demonstrates - that's not it at all.

author: Smokey
author_rank: Super Contributor
timestamp: April 29, 2015, 04:05:27 am
content: I knew I should have qualified thatSorry ahead of time for all the quotes.I wasn't trying to say that just because I'm good at purely mental stuff that that makes me think I would be good at this bike thing. By "mental control systems" I was referring to the virtual control system in your head that closes the loop on these kind of physical motion profiles with various sensory feedback. One example where you can see that mental control loop go unstable is when people over-steer in a car. Lots of overshoot! I was saying I like to think I'm good at those kind of things because I like to learn how to do unusual physical things like this that require some "application specific tuning" to that "mental PID". Riding a unicycle, slack-line walking, juggling, and stuff like that. (Clown college was my backup plan if this EE thing didn't work out). These are all things that are so unnatural that it takes a ton of practice before you can even do them at all. If you train your brain/body for activities which require intensive physical control/feedback tuning, you probably start to develop pathways that make it easier for your brain to pick up other similar activities. Just my unsubstantiated theory.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 29, 2015, 04:07:35 am
content: Quote from: Smokey on April 29, 2015, 01:24:40 amI'd like a bike that goes backwards when you pedal forwards.

author: mtdoc
author_rank: Super Contributor
timestamp: April 29, 2015, 04:16:18 am
content: Quote from: Smokey on April 29, 2015, 04:05:27 amThanks for clarifying. Sorry to be so pedantic but for me the word "mental" implies higher level "executive function" that occurs at the level of the cerebral cortex. I see now that is not how you're using it. Substitute nervous system for mental and I agree with what you say.Cool that you're good at those things. Me, I'm average - but I enjoy trying to learn. I never could get the hang of slack-line walking which has become very big in the rock climbing circles where I once dwelled.

author: zapta
author_rank: Super Contributor
timestamp: April 29, 2015, 02:40:33 pm
content: Reverse steering is actually common in small sailboats and hang gliders. To turn right you push the handle in the other direction and once you get the hang of it it feels just as 'natural'.

author: AndyC_772
author_rank: Super Contributor
timestamp: April 29, 2015, 03:03:55 pm
content: Do any of you guys ride motorcycles?I learned about 5 years ago, and one of the first things we were taught was how to steer a motorbike in a bend.It's not obvious.[Those of you who do ride, will know exactly where I'm going with this already!]When you turn any bike at slow speed - say, doing a U-turn - you turn the handlebars in the direction you want the front wheel to go. Of course you do. Duh.But, once you get a motorcycle moving at speed, something unexpected happens. If you want the bike to turn, you push theinsidehandlebar away from you. So, to turn the bike to the right, you're actually making the front wheel turn to the left, and vice versa.Quite how and where this reversal takes place is beyond my understanding of the geometry and forces involved, but the end result is very real. Push left to turn left, and push right to turn right. Unless you're riding slowly, in which case you turn the bars the other way.Presumably there's some speed at which turning the bars doesn't actually change the bike's direction at all.

author: Lightages
author_rank: Unknown
timestamp: April 29, 2015, 03:26:01 pm
content: Actually, you steer the same way no matter what the speed is, you just don't sense it the same way. Steering a two wheeled vehicle is juggling act of moving the centre of contact on the road too one side or the other from under the centre of gravity. When you are moving, the inertia tries to keep the centre of gravity (CoG) going in the same direction. When you move the bars you angle the wheel so that the tire contact patches move to one side from under the CoG and the bike starts to fall over. You then immediately steer the wheel back under the CoG to keep from falling over. If you do this to keep the bike vertical you continue in a straight line. If you wait till the bike is leaned over a bit and then steer the wheel under the CoG enough to stop the lean but not enough to correct to back to vertical, then you turn or change directions as you keep a sideways acceleration to counteract the lean. To go straight again you steer the wheels back under the CoG.Going straight continuously is a continuous minor correction of the wheel contact patch to stay under the CoG.When you are going fast, the gyroscopic effect of the wheels makes it so you have to apply considerable force the the bars to make the wheel turn and it is obvious what you are doing to the bars. When you are going slow there is no gyroscopic effect and the small movement that you make to start falling over is very fleeting and not obvious but the continuous direction of the bars after to maintain the turn is obvious as it is maintained long enough to sense/see it.Edit: Clarification

author: electr_peter
author_rank: Unknown
timestamp: April 29, 2015, 03:45:25 pm
content: One main idea that was pointed out above is that bike/motorcycle riding is not an act of steering - it is an act of balance. Changing direction of handlebars completely distorts delicate balance and geometry.On the other hand, I would bet that vast majority of drivers could drive a car with reversed steering from second try because steering is completely independent* from other inputs in cars (unlike bikes).* - under typical non-limit and non-extreme circumstances.

author: Bud
author_rank: Super Contributor
timestamp: April 29, 2015, 04:16:30 pm
content: Similarly, time ago i saw a video with a guy trying to ride a bike wearing a closed helmet that had a camera and a screen translating the video to the eyes but the video was translated upside down. All the guy could see is the upside down world and he was tasked to ride the bicycle in that world. It took him a while but eventually he got it. Cant remember who made the video, perhaps it was one of the Myth-busters videos.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 29, 2015, 05:11:31 pm
content: Quote from: zapta on April 29, 2015, 02:40:33 pmIt's also common in the RC world, if the plane/boat/heli/car/quad is flying/crashing towards me, the left/right flips as well. I always imagine myself sitting in the thing and I don't look at the radio. Somehow it mapped over.

author: zapta
author_rank: Super Contributor
timestamp: April 29, 2015, 05:21:18 pm
content: Quote from: Alex Eisenhut on April 29, 2015, 05:11:31 pmYes, good example, and you need to switch constantly between orientations, including upside down.

author: Zero999
author_rank: Super Contributor
timestamp: April 29, 2015, 06:08:08 pm
content: I suspect the reverse steering isn't the difficult part.On a bicycle, some of the steering is done by leaning from side to side, not just moving the handlebars and when one does move the handlebars their centre of balance changes. When the steering on a bicycle is reversed, everything else changes so it's much more complicated than looking at the world upside down or controlling an RC car.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 29, 2015, 06:20:46 pm
content: Quote from: zapta on April 29, 2015, 05:21:18 pmHeh heh, when I use my boat, upside down usually means I gotta put on my rock shoes and climb into the canal...

author: mtdoc
author_rank: Super Contributor
timestamp: April 29, 2015, 06:32:18 pm
content: Quote from: Hero999 on April 29, 2015, 06:08:08 pmExactly. It's much more than feedback from the visual system. It's primarily going to be feedback/control loops using information for proprioceptors in muscles and joints and the vestibular system utilizing feedback from receptors (hair cells) in the inner ear - analogous to a gyroscope. This all happens at a much lower level than the visual system.

author: miguelvp
author_rank: Super Contributor
timestamp: April 29, 2015, 06:58:21 pm
content: Then teens might be the perfect age to learn riding an inverted bike, since they are relearning how to keep their balance every day until they are done growing, and the reason why teens are so clumsy and run into things.

author: Galenbo
author_rank: Super Contributor
timestamp: April 29, 2015, 08:25:39 pm
content: Quote from: Alex Eisenhut on April 28, 2015, 11:16:09 pmOr cross your arms. Hold the left bar with your right hand.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 29, 2015, 10:33:20 pm
content: Quote from: Galenbo on April 29, 2015, 08:25:39 pmThat's the first thing I tried. Nope.

author: Zero999
author_rank: Super Contributor
timestamp: April 29, 2015, 10:42:15 pm
content: Quote from: Alex Eisenhut on April 29, 2015, 10:33:20 pmThat's no surprise. Your balance will be messed up, since you'll be leaning on the opposite side.

author: miguelvp
author_rank: Super Contributor
timestamp: April 29, 2015, 11:30:09 pm
content: I think just changing from pushing the handle bar to pulling with the same hand would do the trick. I guess you could have a contraption that attaches to the bike that would pull when you push counteracting the inverted steering.As others have mentioned at speed you are controlling inclination of the bike to turn, but it's light enough that you body can do the steering, on a heavy motorcycle you have to counter steer to adjust the lean before been able to turn so at that point the handles just act as a tilt mechanism.

author: Smokey
author_rank: Super Contributor
timestamp: April 30, 2015, 03:40:30 am
content: Quote from: miguelvp on April 29, 2015, 06:58:21 pmI thought it was because they were all high on dope! Damn kids and their inverted bicycles always on my lawn!

author: Galenbo
author_rank: Super Contributor
timestamp: April 30, 2015, 08:12:15 am
content: Quote from: Alex Eisenhut on April 29, 2015, 10:33:20 pmDouble inversion doesn't work? Strange.another way: Sit backwards on the steering bar.I tried it with a normal bike, it's very difficult.

author: Rerouter
author_rank: Super Contributor
timestamp: April 30, 2015, 09:48:23 am
content: I have to say on that specific bike, i would have no chance of making the 10 meters without many hundreds of attempts, but in something more similar to my current mountain bike, i could maybe chance it in my first 10 attempts,the swept back handle bars and set forward front wheel makes the balance more heavily influenced by the front wheel, meaning you have to steer, it would not be easy to rely on no-handed balancing, and i strongly suspect that design was picked for that fact, essentially an op amp circuit with too much gain,as the steering axis gets closer to vertical the lean influences a larger turn, so a conventional mountain bike design would allow the rider after the initial push off to rely on standard balance with some difficulty,not saying its an easy task, just the bike was probably chosen deliberately to remove the option of relying on body lean balance,

author: atferrari
author_rank: Frequent Contributor
timestamp: April 30, 2015, 01:31:31 pm
content: Interesting proposalGood example of nonsense and/or futility in action.