Fresh work on the mathematics of bicycles in motion • Hacker News Board

Re: Fresh work on the mathematics of bicycles in motion

#51

Post by willis77 » Wed, Jul 20, 2016, 8:22 PM UTC

icc97 wrote: post #48

If nothing else I find it quite fascinating how some bikes are easier to ride without holding the handle bars than others. I can balance much better on my 1998 Specialized Stumpjumper mountain bike (comfortable for minutes without hands) than I can on my 1998 Cannondale R900 racing bike (max 5 seconds without hand). But for my colleague - he finds it much easier to balance his racing bike. As the article suggest - th…

Some bikes that are hard to ride no-handed have "notched"/"indexed" headsets that are to blame. Small indentations in the headset prevent minor corrections from actually turning the wheel, making it hard to let go of the bars.

http://www.sheldonbrown.com/headsets.html#troubleshooting

(see section on "Indexed Steering")

Re: Fresh work on the mathematics of bicycles in motion

#52

Post by upofadown » Wed, Jul 20, 2016, 8:23 PM UTC

dahart wrote: post #47

upofadown wrote: post #44

Earlier quoted context omitted.

You don't have to countersteer to turn on a bike. When you are riding straight you are using a combination of balance and handlebar position to adjust the angle of the bike so it is directly between you and the ground. If you fail to do this you fall over. So to turn without countersteer just stop doing anything and start to fall over. When you reach your desired angle of bank then turn the handlebars in the directio…

> I personally don't consider "countersteer" to be a thing. It sounds like you've never ridden a motorcycle? Most safety courses on motorcycles teach counter-steering, precisely because it is a thing and failure to understand it can compromise your ability to recover from a bad situation. On a motorcycle going fast, you counter-steer continuously. If you make a slow right turn on a freeway, you can turn for 30 second…

>there's only one way to turn without leaning

I generated an argument that refutes that statement in the post you are responding to. I am not arguing that the effect does not exist, only that it isn't interesting and is not worthy of a special term to describe it.

FWIW I ride motorcycles on a regular basis... I oppose the discussion on countersteering in the regular motorcycle training curriculum because it suggests that there is more than one type of turn for no real reason. It would be better just to say that you turn on a motorcycle by changing the angle of the motorcycle from vertical. Then there is only one thing to learn.

Re: Fresh work on the mathematics of bicycles in motion

#53

Post by speps » Wed, Jul 20, 2016, 8:25 PM UTC

sevenless wrote: post #8

It might help if they program humanoid robots to ride bikes. The problem seems to be hard to analyze because there's a person on the bike, and the way the person moves with the bike is hard to track.

Like this? http://www.cc.gatech.edu/~jtan34/project/learningBicycleStun...

Re: Fresh work on the mathematics of bicycles in motion

#54

Post by davidw » Wed, Jul 20, 2016, 8:25 PM UTC

icc97 wrote: post #48

If nothing else I find it quite fascinating how some bikes are easier to ride without holding the handle bars than others. I can balance much better on my 1998 Specialized Stumpjumper mountain bike (comfortable for minutes without hands) than I can on my 1998 Cannondale R900 racing bike (max 5 seconds without hand). But for my colleague - he finds it much easier to balance his racing bike. As the article suggest - th…

Peter Sagan showing how well some people can ride with no hands: https://streamable.com/2u94

(From today's stage of the Tour de France)

Re: Fresh work on the mathematics of bicycles in motion

#55

Post by dahart » Wed, Jul 20, 2016, 8:38 PM UTC

upofadown wrote: post #52

dahart wrote: post #47

Earlier quoted context omitted.

> I personally don't consider "countersteer" to be a thing. It sounds like you've never ridden a motorcycle? Most safety courses on motorcycles teach counter-steering, precisely because it is a thing and failure to understand it can compromise your ability to recover from a bad situation. On a motorcycle going fast, you counter-steer continuously. If you make a slow right turn on a freeway, you can turn for 30 second…

>there's only one way to turn without leaning I generated an argument that refutes that statement in the post you are responding to. I am not arguing that the effect does not exist, only that it isn't interesting and is not worthy of a special term to describe it. FWIW I ride motorcycles on a regular basis... I oppose the discussion on countersteering in the regular motorcycle training curriculum because it suggests…

You actually described counter-steering, even though you might disagree. ;) You said that I can lean right to start a right turn, then turn the handlebars into the turn as soon as you want to stop decreasing the turning radius. That is part of counter-steering. Turn the handlebars right to begin turning the bike left -- that can and does include slowing down an increasing right turn until it's at a constant turning radius.

That's why you're always counter-steering on a two-wheeled vehicle; because turning the handlebars right of where they currently are always causes you to turn more right of where you'd have gone if you didn't move the handlebars.

Since you ride motorcycles, then you already know anyone who's facing a quick turn definitely does not want to wait to fall. To turn quickly, you must counter-steer.

I am curious why you think it's not worth a special term, when it's unintuitively opposite from the way car steering works, and it's important to know in order to stay safe?

Re: Fresh work on the mathematics of bicycles in motion

#56

Post by cel1ne » Wed, Jul 20, 2016, 8:50 PM UTC

no_flags wrote: post #9

Avid cyclist, but I have no idea what this is talking about: "...the phenomenon of 'countersteering', whereby the rider can steer to the left only by first briefly torquing the handlebars to the right, allowing the bike to fall into a leftward lean." Am I just doing this subconsciously?

Yes. What's more you actually change the direction above a certain speed like 5km/h or so.

Prior to that you turn the bar into the direction you want to go, above that you do the opposite. The cerebellum rules.

When riding a motorcycle it's very noticeable. Just tipping the handlebar with the finger at 100km/h and it will lean into the other direction.

Re: Fresh work on the mathematics of bicycles in motion

#57

Post by dahart » Wed, Jul 20, 2016, 8:58 PM UTC

_Wintermute wrote: post #30

HCIdivision17 wrote: post #16

Earlier quoted context omitted.

It's wildly unintuitive, so don't feel bad. When I was first learning to ride a motorcycle with the MSF, I damn neared dumped the practice bike a few times trying to manhandle it. You'll really quickly internalize push-left-go-left. And it turns out to work great on regular bikes, too. (But it's terrifyingly more responsive - I actually can't relax pedaling a bicycle because of the fear of how easy it is to flip the…

> And it turns out to work great on regular bikes, too Well yes, seeing as that's how you steer a bicycle. As a keen cyclist it annoys me when people (especially coaches) start harping on about countersteering being an additional technique you should learn, when it's what everyone has been doing intuitively since they first learned to ride a bike.

We learn counter-steering subconsciously, right? It's intuitive in the sense that it's muscle memory, but not in the sense that it's conscious and obvious why. A lot of people who've ridden bicycles initially refuse to believe counter-steering exists, I think that demonstrates that it's not completely intuitive. If the counter-steering part is obvious to you, then you're probably ahead of the curve, and you can certainly ignore when coaches harp about it.

Counter-steering is said to be important to learn consciously because it's unintuitive, and people have crashed and died on motorcycles in panic situations by turning their handlebars toward their escape route only to have the bike go the opposite direction. Or at least I heard a rumor about that in my MSF course.

I do think it's valuable to know this fact consciously and not rely on body intuition, but I'm also sure it's much more important for motorcycling than for bicycling.

Re: Fresh work on the mathematics of bicycles in motion

#58

Post by fiftyacorn » Wed, Jul 20, 2016, 9:21 PM UTC

maaaats wrote: post #22

> ...an ambitious effort that would investigate everything from the strength of wheels... My master touched this. Used AI to find spoke patterns. http://master.matsemann.com > There were untested geometries out there that could transform bike design. Better hardware and simulations makes it easier to test thousands of these, possibly with the help of AI. I wonder if any drastically new designs will be found in the fe…

Thats an interesting pattern - but the issue is how would you true a wheel like that?

Re: Fresh work on the mathematics of bicycles in motion

#59

Post by kqr » Wed, Jul 20, 2016, 9:31 PM UTC

ranko wrote: post #17

no_flags wrote: post #9

Avid cyclist, but I have no idea what this is talking about: "...the phenomenon of 'countersteering', whereby the rider can steer to the left only by first briefly torquing the handlebars to the right, allowing the bike to fall into a leftward lean." Am I just doing this subconsciously?

Yes, you're doing it subconsciously. Countersteering is only possible on two-wheeled vehicles, which means that tricycles handle very differently to bikes, and that learning to ride with stabilisers (training wheels) can be counterproductive.

This totally explains my early, only, very bad experience with training wheels. I went right out into the street because I turned the wrong way and my friend (who had the training wheel bike) thought I knew nothing about riding bikes. I just learned without training wheels...

Re: Fresh work on the mathematics of bicycles in motion

#60

Post by c0nsumer » Wed, Jul 20, 2016, 9:40 PM UTC

dahart wrote: post #47

upofadown wrote: post #44

Earlier quoted context omitted.

You don't have to countersteer to turn on a bike. When you are riding straight you are using a combination of balance and handlebar position to adjust the angle of the bike so it is directly between you and the ground. If you fail to do this you fall over. So to turn without countersteer just stop doing anything and start to fall over. When you reach your desired angle of bank then turn the handlebars in the directio…

> I personally don't consider "countersteer" to be a thing. It sounds like you've never ridden a motorcycle? Most safety courses on motorcycles teach counter-steering, precisely because it is a thing and failure to understand it can compromise your ability to recover from a bad situation. On a motorcycle going fast, you counter-steer continuously. If you make a slow right turn on a freeway, you can turn for 30 second…

I mountain bike regularly, and I actively counter-steer all the time. It's super obvious if you know what to look for. I personally most feel it when doing fast, flat, sweeping turns. I lean the same direction as the turn, and the bike will feel like it wants to fall further in, making the turn sharper and sharper.

Pushing on the side of the handlebar on the direction I'm turning counters this desire of the bike to fall into the turn. That's counter-steering. It's a pretty unconscious action, and to most feels like what comes natural when one leans a bike to turn.