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Oh cycle physics again, un-sarcastic yay! I'd love to try that challenge, I like to think I'd get the hang of it after an hour or so. I suppose very little rake/trail also helps make it harder. I was cycling with some friends earlier this summer at Tempelhof airport in Berlin, a closed runway leaves plenty of room for physics fun. I explained countersteering to the others and none of them believed me, maybe not quite getting what I was saying. But once they tried it deliberately, they suddenly realized that's how they had been cycling all their life. On a bicycle it's also easier to try the opposite, turning the handlebars the "right" way. It doesn't take much speed before it's impossible. Slavvy posted:
Yeah, if you welded the forks straight, you'd go straight. Leaning does, in a way, the same thing as steering does. It changes the balance of the bike so it tips in to the turn. Then once the steering input stops, the wheel falls in towards the direction of the turn, all forces are in balance and the wheel tracks the same circle the bike is describing.
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Jul 29, 2014 20:10
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Slavvy posted:Also this pretty much proves leaning the bike does jack poo poo in itself.  I think you have this backwards? You can steer the bike perfectly fine with nothing more than a weight-shift-induced lean. There's no need to touch the handlebars -- you should know this from when you were a kid. Yeah, the bars turn automatically, but the initial lean doesn't need to be initiated from the bars.On the other hand if you're saying that the bike wouldn't turn if the front wheel wasn't free to turn, no matter how far you leaned it over -- well that's true but like, duh. e: yeah Sagebrush fucked around with this message at 20:20 on Jul 29, 2014 |
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Jul 29, 2014 20:18
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Sagebrush posted:
You're totally wrong about this by the way. There have been motorcycles built where you can't turn the bars and you can barely get the bike to move with weight shifting.
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Jul 29, 2014 20:27
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ShaneB posted:You're totally wrong about this by the way. There have been motorcycles built where you can't turn the bars and you can barely get the bike to move with weight shifting. I don't think you're following what we're talking about, here.
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Jul 29, 2014 20:39
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On the other hand, sometimes when riding my motorbike, I will turn left with only my right hand on the bars, by pulling the bar back towards me instead of pushing with my left hand, because countersteering is totally a thing.
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Jul 29, 2014 20:39
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I don't see a weight shift induced lean at anything above walking speed working to steer the bike. At actual road speeds, shifting weight just moves you laterally a little while still shooting straight. I cant tell if hcc is serious or not because what he wrote has a serious case of the dumbs.
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Jul 29, 2014 20:49
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1. all single-track two-wheeled vehicles lean to turn 2. it doesn't matter how you initiate the lean as long as the required torque is there to keep the bike leaned 3. when you countersteer you create the torque at the front wheel by levering it over from the bars 4. if you were a giant fatass you could create the same torque by hanging off teh side of the bike, without touching the bars 5. "moving laterally a little" is by definition a steering motion, just not a very big one 6. on a bicycle, which is what we were talking about, the required torque is much less because the vehicle weighs less so a normal-weight person can steer by leaning the bike without touching the bars 7. hcc is correct, you can push on the inside bar or pull on the outside bar to initiate a countersteer, i do this all the time when i'm being lazy and following a car dawdling along at 20mph jesus.
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Jul 29, 2014 21:01
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HotCanadianChick posted:On the other hand, sometimes when riding my motorbike, I will turn left with only my right hand on the bars, by pulling the bar back towards me instead of pushing with my left hand, because countersteering is totally a thing. I do this quite a lot. Pulling the outside bar in as I lean in to the turn and sort of lifting the bike up with the inside bar as I start leaning out again. EX250 Type R posted:I don't see a weight shift induced lean at anything above walking speed working to steer the bike. At actual road speeds, shifting weight just moves you laterally a little while still shooting straight. Go try it, you can steer easily and predictably. I recommend a high gear on a straight slight downhill because of the engine braking, just from one side of the lane to the other to get a feel for it. You will also discover if your bike tracks true or not and how much small undulations in the road affect the direction of your bike - which you don't normally notice because you keep steering it straight. Don't crash.
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Jul 29, 2014 21:02
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The reason why HCC sounded dumb is because its a stupid thing to say. Left side pushed in is the exact same as the right side pulled out. Literally, the same. exact. thing. As far as steering, you won't be negotiating any actual turns without your hands on the bars, at road speed. So by saying you can go from the yellow line to the white line by shifting body weight and then calling that steering is pretty loving stupid.
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Jul 29, 2014 21:07
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EX250 Type R posted:The reason why HCC sounded dumb is because its a stupid thing to say. Left side pushed in is the exact same as the right side pulled out. Literally, the same. exact. thing. I'm not saying you are physically limited to going from the yellow line to the white line, I am saying you should limit yourself to that when trying it for the first time to be safe. It's slower and less accurate than using your hands so trying it around a corner would be pretty loving stupid. https://www.youtube.com/watch?v=HuRlxpC9l-g
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Jul 29, 2014 21:24
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Bike is following the camber of the road.
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Jul 29, 2014 21:27
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Leaning the bike without using the bars does nearly nothing. I remember watching a video somewhere where they welded on a second set of bars directly to the frame, above the normal controls, which were completely rigid and only had a throttle, clutch and brake. The guy was fully throwing his weight side to side and it barely made the bike change direction at all; he actually ended up drifting off into the grass because he couldn't correct a slight wander to the left. Turning the bars makes the bike lean, but that isn't what makes it steer. It's the fact that it's continuously 'falling' because the front wheel is trying to steer outwards, away from the direction of turning, causing the bike body to flop over the other way, along the axis of rotation of the front wheel. If you try just pushing the bike while walking alongside, then twist the bars away from you (so turn them left if you're on the right and vice versa), the bike will do it's best to fall on top of you. The fact that you don't fall while moving is because your forward momentum stops you completing the fall, so you're constantly 'falling'. The best analogy in my mind is the way objects in orbit stay in orbit. They're constantly 'falling' but moving fast enough in relation to the earth that they can never complete the fall.
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Jul 29, 2014 21:30
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https://www.youtube.com/watch?v=HOGQ-HePrT8 You can make a lazy turn by bouncing on the pegs and loving with your body weight, but ultimately countersteering is the only way to functionally turn a bike at any reasonable speed. Z3n fucked around with this message at 21:35 on Jul 29, 2014 |
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Jul 29, 2014 21:32
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Slavvy posted:The guy was fully throwing his weight side to side Nuh uh. In Z3n's vid, he keeps his weight mostly over the middle and points his foot backwards. Even that causes noticable change of direction. Then he shakes the rigid bars. Ho hum. The guy in my vid actually leans to change the balance. What works on a bicycle works on a motorcycle, just at different rates and amplitudes. I urge everyone to try it out for themselves. n8r posted:Bike is following the camber of the road. The first turn. He steers out of it against the camber. And bikes don't follow the camber that much, think of how many crashes wide on that corner. Z3n posted:functionally turn a bike at any reasonable speed. Functionally turn, as in steering it at all and with purpose? You can do that by shifting your body weight, try it tomorrow. (e: timezone, try it now.) You need to shift it more than feels comfortable, be safe. But safely, effectively, quickly and precisely turn? Yeah, use the bars. Ola fucked around with this message at 21:44 on Jul 29, 2014 |
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Jul 29, 2014 21:41
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This is like saying dragging your feet on the road slows you down. Technically correct, functionally worthless. Also only works at low speed. Try to turn a bike at 40mph with body input only, and at best you get a lazy arc. That guy can do it down the snake cause they're going incredibly slowly (not over 25mph).
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Jul 29, 2014 21:45
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Get a cruiser with crash bars and highway pegs and you can use your feet to flex the geometry enough for some reasonable steering input. That's about all I'd do on the interstate when I was riding the butterframe Vulcan.
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Jul 29, 2014 21:56
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See, this is why I love this topic. Off we go.Slavvy posted:Leaning the bike without using the bars does nearly nothing. Yes it does. Leaning the bike makes it turn (and steering the bars makes it lean). Leaning your body just a little bit might not make it turn. Slavvy posted:Turning the bars makes the bike lean, but that isn't what makes it steer. It's the fact that it's continuously 'falling' because the front wheel is trying to steer outwards, away from the direction of turning, causing the bike body to flop over the other way, along the axis of rotation of the front wheel. The front wheel is not pointing away from the turn when you are in a turn, it is pointing into the turn. When you want to lean left, you turn right. Then feel what the bars do, they settle back to the left. Some nice views of that here, particularly at 2:44. https://www.youtube.com/watch?v=C848R9xWrjc Slavvy posted:If you try just pushing the bike while walking alongside, then twist the bars away from you (so turn them left if you're on the right and vice versa), the bike will do it's best to fall on top of you. This is what it does at speed as well. Turn the bars one way, it wants to fall the other way. Slavvy posted:The fact that you don't fall while moving is because your forward momentum stops you completing the fall, so you're constantly 'falling'. The best analogy in my mind is the way objects in orbit stay in orbit. They're constantly 'falling' but moving fast enough in relation to the earth that they can never complete the fall. No, it's possible to steer into the ground at speed, it just happens differently at speed. The bike is steering fine until it runs out of lean angle, scrapes something solid and you fall. At rest, there is nothing to counteract gravity that wants to make it fall so it just flops over. At speed, the turn itself provides the balance. And it's not passive like a spaceship in orbit, it's you with your constant, often imperceptible steering inputs that is keeping the bike in the desired direction, whether going straight or holding a constant corner.
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Jul 29, 2014 22:01
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Let's watch motorcycle videos... https://www.youtube.com/watch?v=Tol-U36jXGM
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Jul 29, 2014 22:01
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My route home includes three fairly steep hills which I invariably descend with my hands off the bars and the bike in sixth at 60-80km/h. I can make the bike change direction slightly by moving my weight, enough to regulate my position in the lane, but I wouldn't call that 'turning' or 'steering'. I'd say leaning the bike is around a 5% contributor to going around corners. This is supported by the fact that you often see idiots going around corners just fine despite their body being vertical (relative to the ground) instead of leaning with the bike. They're actively fighting the lean and the bike still turns fine, because it's the steering input that actually makes the thing turn.
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Jul 29, 2014 22:02
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Ola is clearly a physicist or something. Some sort of foreign ministry scientist, and sounds like he knows his poo poo. I'm going with Ola 
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Jul 29, 2014 22:06
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Z3n posted:This is like saying dragging your feet on the road slows you down. Technically correct, functionally worthless. Yes. Dragging your feet will functionally slow you down, but not safely, wisely or practically. Functional = works at all, it isn't physically impossible. Practical = is a good thing to do, isn't stupid. Z3n posted:Also only works at low speed. Try to turn a bike at 40mph with body input only, and at best you get a lazy arc. That guy can do it down the snake cause they're going incredibly slowly (not over 25mph). Nope, it's just harder at higher speeds. The physics at 25 mph doesn't stop working at 40, it's just more stupid and harder to do. The tiny corrections you do so quickly and easily with tons of leverage on the bars require massive moves of balance which is why the guy is going slow, yet in a wallowing, imprecise way. So it's not physically impossible, even if it's practically unsound. You can steer a bike by shifting your body weight. I urge everyone to give it a try. You'll wallow, so be careful. SaNChEzZ posted:Ola is clearly a physicist or something. Some sort of foreign ministry scientist, and sounds like he knows his poo poo. I'm going with Ola Thanks!  I'm not a physicist, I've just tried it and paid attention to what it did!
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Jul 29, 2014 22:10
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Slavvy posted:My route home includes three fairly steep hills which I invariably descend with my hands off the bars and the bike in sixth at 60-80km/h. I can make the bike change direction slightly by moving my weight, enough to regulate my position in the lane, but I wouldn't call that 'turning' or 'steering'. That's exactly what it is, it's just not a lot of it. Change your weight around a lot, the bike steers more. Slavvy posted:I'd say leaning the bike is around a 5% contributor to going around corners. This is supported by the fact that you often see idiots going around corners just fine despite their body being vertical (relative to the ground) instead of leaning with the bike. They're actively fighting the lean and the bike still turns fine, because it's the steering input that actually makes the thing turn. Now your mixing things. You might see many morons, but you never see one going around a corner at speed with the bike perfectly vertical, unless it's a trike or has a sidecar. Leaning the axis of the bike, i.e. the angle between the bike's height and the ground is a 100% contributor to turning it. (exception: you go so slow that the bike's turn does not make it fall outward) But changing the axis of your body in relation to the axis of the bike is something else, it changes its balance. Changing the bike's balance makes it lean, a leaning bike will turn. You can change the balance of the bike quickly and effectively by turning the bars, or clumsily and poorly by leaning your body one way or the other. The handlebar steering input is much more effective than the body lean, which is why you can lean your body in the opposite direction of a turn yet still easily turn into it with the handlebars.
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Jul 29, 2014 22:25
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People can argue about it all you want but I've set the throttle lock and ridden with both hands off the bars. You won't be setting lap records but you can definitely ride street pace by doing it. It's still turning by counter-steering, just using weight input into the pegs to move the bars as opposed to my hands.
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Jul 29, 2014 22:32
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Just going to throw the words "castor angle" into this conversation and then run.
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Jul 29, 2014 22:35
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nsaP posted:People can argue about it all you want but I've set the throttle lock and ridden with both hands off the bars. You won't be setting lap records but you can definitely ride street pace by doing it. It's still turning by counter-steering, just using weight input into the pegs to move the bars as opposed to my hands. Just before I run - what the gently caress do you think counter steering actually means? You cannot countersteer with your hands off the bars, by definition. (I suspect this might be at the heart of the argument here - people seem to think "countersteering" is any deviation of the front wheel from the axis of travel and it's not - that's just steering. It specifically means using steering input to get the bike to lean, to then allow you to steer the bike through the corner.)
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Jul 29, 2014 22:38
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goddamnedtwisto posted:Just before I run - what the gently caress do you think counter steering actually means? You cannot countersteer with your hands off the bars, by definition. He's still countersteering just in reverse by leaning he bike over using his body weight he's causing the bars to move, instead of the other way around.
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Jul 29, 2014 22:45
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Jesus Christ this is the most absurd argument. It is possible to turn a bike without using the bars, just not with any measure of precision, speed, or accuracy. I value all of those things, so using body weight to turn a bike is functionally worthless to me.
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Jul 29, 2014 22:45
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goddamnedtwisto posted:
Yes, countersteering should really be called steering. That's how you steer a bike at speed, it's not a clever trick you need to know just in case, you do it every time. To turn left, the bike needs to lean left. To lean the bike left, you need to turn the handlebars to the right. If the turn is so slow it doesn't need to lean, i.e. walking pace, you can turn left by turning the handlebars left. So tugging at the handlebars is one type of steering input and leaning your weight over to one side is another. But the handlebars/forks/wheel do the same thing. While starting the lean, the wheel starts pointing out, when stabilized in the turn it points in, regardless of which rider input initiated the lean.
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Jul 29, 2014 22:46
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Z3n posted:Jesus Christ this is the most absurd argument. It is possible to turn a bike without using the bars, just not with any measure of precision, speed, or accuracy. I value all of those things, so using body weight to turn a bike is functionally worthless to me. At least it's not so absurd that you can't agree! Albeit perhaps not on the exact definition of the word function.
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Jul 29, 2014 22:48
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Youtube's angriest motorcycle vlogger is back. https://www.youtube.com/watch?v=nKi3KOntM1I
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Jul 29, 2014 22:58
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I don't think anyone has claimed that steering by shifting your weight side to side is ever a good idea or a more effective or precise way of controlling the bike. The argument is just "is it possible to do so?" and the answer is absolutely yes. Motorcycles are dynamically stable in a straight line, and countersteering is a way of upsetting that balance to induce the lean that causes the turn on the frog on the log on the bottom of the sea. If you can upset the balance in another way and induce the same lean, you can cause the same turn. It's trivial to steer a bicycle by shifting your hips side to side -- I can ride my bike indefinitely and turn steeply enough to make U-turn in two lanes without touching the bars. I bet if you analyzed it in some detail, the only difference between that situation and the one you're in on a motorycle is that the vehicle outweighs you by three or four times, instead of you outweighing it by the same amount. That's what makes me imagine that if you weighed like five hundred pounds, and could shove all that mass over to one side or the other of the vehicle, you could no-hands a motorcycle the same way an average person can a bicycle.
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Jul 29, 2014 23:02
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hot sauce posted:Youtube's angriest motorcycle vlogger is back. I think this guy does a pretty good job of capturing my own inner monologue while commuting. I don't think I'd get quite as annoyed with a student driver though - unlike him, I'd just honk with full intenetions of being a prick.
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Jul 29, 2014 23:19
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https://www.youtube.com/watch?v=Fo_KIZ7xUbc
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Jul 29, 2014 23:28
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goddamnedtwisto posted:Just going to throw the words "castor angle" into this conversation and then run. Of course a Brit riding an Italian bike would bring up this load of pollux
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Jul 29, 2014 23:37
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This arguement is so loving stupid. You can turn the bike with just shifting your body weight, I do it all the time, it's not as effective as using the bars but it works. If you don't believe it happens, you will if you go out and actually do it. Holy poo poo. On non-stupid topics;   I got some PR4s yesterday, new chain too. They're great.
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Jul 30, 2014 01:39
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I'd love a pair of PR4s but my PR3s don't want to wear out.
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Jul 30, 2014 01:42
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lol. I got a little over 25,000kms out of my PR2s, looking forward to seeing what absurd number I can get out of these!
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Jul 30, 2014 02:05
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Every time I see something about countersteering the scientist inside me cringes, and I'm not even a physicist. It's very obvious that at higher speeds, there's no 'bike falling in the other direction' happening. We don't see motoGP riders do this, and for good reason. Why does countersteering work? Because your front wheel is a giant loving gyroscope. If you push a force against a gyroscope that's spinning, your force affects the gyroscope at a right angle from where that force is applied. It's the same reason that heli blades are actually set up in a very odd manner: https://www.youtube.com/watch?v=eTjGTxSevHE. Once you can actually reliably apply force at a given point on the gyroscope disk, you can very easily make it turn at a given angle while still having it act in a stable manner. Moving on to bikes, your front wheel is a gyroscope. You apply force on the inside handlebar of a turn, which would otherwise push your front wheel outwards. Because it's a gyro, you're actually applying that force 90 degrees further. What does that do? It actually pushes the gyro over, making it lean. Essentially, by pushing the handlebar, you're putting a turning force on the gyro disk that gets displaced at a right angle and actually leans the bike. This also explains why the steering rake affects how stable a bike is: the greater the angle, the more that counter-steering force is deflected on the gyro, and the less directly it's leaning the bike. How do we KNOW that this 'falling over the other direction first' is bullshit? Because if you're already in a turn, you can increase the lean or decrease it using the same gyroscopic force. You can't go around and fall over a little again in the middle of a corner. You CAN affect the gyroscopic force on your bike. Barnsy fucked around with this message at 02:21 on Jul 30, 2014 |
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Jul 30, 2014 02:16
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That's all well and good except actual physicists have built bicycle models that have counter-rotating wheels to cancel out all gyroscopic effects, and the things still work. http://en.wikipedia.org/wiki/Two-mass-skate_bicycle The best thing to say is that it is a whole pile of different forces and not a single person here actually understands what is going on. http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics
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Jul 30, 2014 02:56
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To add to that there was that one guy that made reverse rotating rotors on the front of his motorcycle and it still steered pretty normally.
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Jul 30, 2014 03:30
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