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>Do you remember the insights that were crucial in learning to ride a bike or drive? The author mentioned bicycles and inadvertently missed an opportunity to s
by jasode 9y ago
>Do you remember the insights that were crucial in learning to ride a bike or drive?
The author mentioned bicycles and inadvertently missed an opportunity to show another "unknown reality" that beautifully illustrates his point.
Consider typical adults (not physicists) with 20+ years of bicycle riding. If you ask them, "how does a bicycle turn?", they'd respond that "you just lean into the direction of the turn and it turns."
But that's not the complete picture of what actually happens.[1] If you were to capture the bicyclists with a high-speed camera, you'd notice that there's always a micro movement of countersteering to make the bike momentarily lose its balance and "fall into" the turn. Then there's an immediate correction of the steering to match the turn. This all happens in the span of milliseconds.
Even though the human body "discovered" the countersteering by way of kinesthetic feedback, the bicyclists' brains don't explicitly communicate this intermediate step to others. (Tacit knowledge.[2])
It's not always the case that we "simplify" reality for innocent purposes of pedagogy. (E.g. we tell "lies" to children about "numbers", "functions", etc and as they get older, we successively remove the layers of lies as they get into high school and college math.) Instead, we often don't even know the reality (e.g. bicycle countersteering) to consciously omit it.
That extra reality may not even be important. If one human is teaching another human, you can leave the "countersteering" detail out and it won't matter. The 200 years of people learning how to ride bicycles is evidence of that. However, if you're a robotics scientist and want to build a self-driven motorcycle, the reality of countersteering becomes a crucial detail.
[1] https://www.youtube.com/watch?v=llRkf1fnNDM https://www.youtube.com/watch?v=llRkf1fnNDM
[2] https://en.wikipedia.org/wiki/Tacit_knowledge https://en.wikipedia.org/wiki/Tacit_knowledge
- jerf 9y agoSee also: https://www.youtube.com/watch?v=MFzDaBzBlL0 https://www.youtube.com/watch?v=MFzDaBzBlL0 YouTube channel Smarter Every Day tries to ride a bike that has been hacked to reverse which way the wheel goes when the handlebars are turned, which also reveals how much bike riding skill is implicit. (I also experience the "clicking" he refers to around 6:10 when I switch between QWERTY and Dvorak layouts. It takes about 15-30 seconds to switch, even after all the years I've been doing this, and I can "feel" it slide into place. This despite the fact that I use Swype (or whatever it is spelled as) on my phone all the time, which means I stay very familiar with the QWERTY layout every day... but somehow that qualifies as a different "thing", because I always get that instantly.)
- seszett 9y agoAbout your keyboard, my experience after having used both a (Canadian multilingual) QWERTY MacBook and other computers with regular AZERTY keyboards for years, is that everytime I use some keyboard that vaguely feels Apple-y (with flat keys, white or grey) I somehow try to use it as a QWERTY. Then after a few seconds of mistyping things, I can eventually use it correctly, but it really seems like it's the look of the keyboard that makes me choose which layout I use. It's probably different for everyone, in my case my brain has found the look of the keyboard to be the best predictor, for others it could be something else. But it's really interesting, sometimes it takes me a while before I notice that, indeed, this keyboard looks a bit like a Mac keyboard.
- taneq 9y agoI had this the first time I rode a motorcycle. The first day, everything was really jerky and uncoordinated because I had to do everything consciously. Woke up the next morning and my brain had remapped clutch from left foot to left hand, throttle/brake from right foot to right hand, gears from left hand to left foot, and the bike "just worked" the way I expect cars to.
- dekhn 9y agoA long part of my scientific career has been unpacking simple statements about things like bike riding, and finding the underlying process is subtle, and reveals many interesting things. When I was a kid, I had a teacher who said that cutting paper wasn't a chemical change- no bonds were broken. That seemed odd to me, but after I had a PhD, I understood a few things better. That when you cut paper, mostly hydrogen bonds- bonds, but a particularly weak form of bonds- are broken, but threre is enough kinetic energy to break some covalent bonds too. This turns out to have huge implications (besides the fact that the teacher was wrong).
- telchar 9y agoI'll bite.. what are the huge implications?
- sudhirj 9y agoCould striking a match be viewed as cutting paper?
- dekhn 9y agono, that's combustion, clearly a chemical reaction. Sure, you can use a laser to cut paper, but the teacher was talking about scissors.
- mikepalmer 9y agoAnd... what are the huge implications??
- appearsonline 9y agoCome on dekhn, we want to know
- dekhn 9y agoOK, sure. One of the most interesting long-running issues in proteins is how they adopt their 3D structure and remain stable for such long periods. Most people would say that covalent bonds hold the protein together and they dominate the overall structure- for example, you wouldn't ever see a strained covalent bond, so you can easily eliminate all structures with strained bonds. This was long an assumption. However, work I did at Google using Exacycle demonstrated that, in fact, large collections of hydrogen bonds can in fact work in concert to stabilize proteins with strained covalent bonds (http://onlinelibrary.wiley.com/doi/10.1002/pro.2389/full http://onlinelibrary.wiley.com/doi/10.1002/pro.2389/full), which overturned the assumption, and made a modest contribution to the prediction of protein folds, and protein design.
- littlestymaar 9y ago> If one human is teaching another human, you can leave the "countersteering" detail out and it won't matter. The 200 years of people learning how to ride bicycles is evidence of that. This is actually a well-known fact about motorcycle, and it's taught in driving schools. It's just that their is no bicycle driving school and people just figure it by themselves. I'm pretty sure it takes more time though.
- dingo_bat 9y agoI don't think regular driving schools teach you to countersteer when you turn.
- littlestymaar 9y agoOh interesting, in what country do you live ?
- dingo_bat 9y agoIndia. We're not known for the thoroughness of our driving schools :)
- tonyhb 9y agoMy dad owns a motorcycle training school and teaches this.
- deleted 9y ago[deleted]
- acranox 9y agoThe motorcycle class I took in the US did in fact teach this.
- 24gttghh 9y agoPerhaps they mean riding schools as any MSF endorsed riders course will teach you to counter-steer to initiate a turn [0] at higher speeds. It is especially important on a motorcycle due to the forces/speeds involved. [0]http://www.msf-usa.org/downloads/BRCHandbook.pdf http://www.msf-usa.org/downloads/BRCHandbook.pdf (sec.4, pg.8)
- tome 9y agoHave you actually tried turning a bicycle without countersteering? I have, the last time the topic was discussed on HN. I found I was able to turn without any perceptible countersteer. It's technically possible that I do have to countersteer for a small number of miliseconds over a small number of milimeters, but my experience leads me to doubt it.
- daveguy 9y agoIf you have a normal bicycle without modifying the steering column then you were using countersteer whether you realized it or not. Even if you weren't toughing the handlebars, the lean initiates a countersteer. And you need countersteer again in the opposite direction to re-center yourself. If there's video or experimental setup info I'd like to see it.
- monochromatic 9y agoA moped (and I assume a motorcycle) is a lot harder to turn without countersteering. I’m not sure if that’s because it’s more massive or what. Anyway, learning to ride a moped was when I first consciously discovered countersteering. It made things a lot easier after that point.
- hornbaker 9y agoIt could be based on speed rather than mass. Above 5-10 mph or so, you turn a motorcycle with pretty much total countersteering, forcefully pushing forward on the inside hand grip to get the motorcycle to lean over. The faster you're going, the further you need to lean the motorcycle.
- monochromatic 9y agoThat makes sense too.
- taneq 9y agoThe geometry is set up to be stable at a higher speed. Even then some sports bikes require a steering dampener to prevent "speed wobbles" (which, yes, are an actual thing and are much worse at 260kph than at 30kph on your BMX when you're a kid.)
- beat 9y agoFor guitar nerds, there's a whole online business by a guy named Troy Grady about fast picking techniques (he has a ton of extremely polished videos on YouTube - start with whatever "Cracking the Code" videos are up). He decoded the seemingly-magical techniques that allow players like Yngwie Malmsteen and Eric Johnson to play at what feel like impossible speeds, and illustrates them. (tl;dr the core trick is "pick slanting", striking the strings at an angle so the pick goes in and out of the plane of strings, rather than across it, and then switching strings only when the pick is "out". That, and "chunking", breaking into units of fixed length on a single string and using the fixed length to do a clock reset on the beats). For a guitarist, it's almost impossible to explain the myriad tiny details that go into something as seemingly simple as picking a note. Troy's analysis of instructional videos by great players, where they obviously don't understand what they're doing, is kind of amazing. And a real eye-opener, for those of us who have played a long time.
- cosmotron 9y agoThere's another neat example of this: asking someone with years of car-driving experience to hold their hands out as if gripping a steering wheel and mime the motions necessary to change lanes. [1] The steps are: 1. Turn the steering wheel towards the lane you wish to enter, 2. Re-center the steering wheel, 3. Counter-steer the same amount as in step 1. Step 3 is what people tend to forget about. [1] https://99percentinvisible.org/episode/episode-37-the-steering-wheel/ https://99percentinvisible.org/episode/episode-37-the-steeri...
- pwinnski 9y agoFor step 3, I almost always loosen my grip on the wheel and let it mostly straighten myself. So miming wouldn't include nearly as much counter-steering, even if I did remember to mime the whole process.
- iClaudiusX 9y agoYou skipped the turn signal, which seems accurate to most of the drivers I see on the road.
- jccooper 9y agoIf anyone ever refuses to believe this, have them steer using just their palms. Especially, try to turn left or right using just one palm.