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

Re: Fresh work on the mathematics of bicycles in motion

#81

Post by sohkamyung » Thu, Jul 21, 2016, 1:39 AM UTC

HCIdivision17 wrote: post #67

Someone wrote: post #43

Earlier quoted context omitted.

Bikes balance themselves; they don't need a rider to do it for them. Watch https://www.youtube.com/watch?v=oZAc5t2lkvo

I just want to note that this also happens on motorcycles. On a cold winter day my bike dumped me off as I lost traction at a stop light. It started to fall over, bumped its saddle bags, and before the tilt sensor could stall the engine it righted itself in second gear and idled its way through the intersection... with me literally running after it. It hit a curb and eventually stalled upright. Second most embarassin…

Dare I ask what was the most embarrassing thing the bike did to you?...};-)

Re: Fresh work on the mathematics of bicycles in motion

#82

Post by afroviking » Thu, Jul 21, 2016, 1:43 AM 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?

There's a very interesting video from Keith's Code's superbike school where they built a motorcycle with an extra handle bar that's fixed to the bike to prove that leaning doesn't actually turn the bike much at all.

https://www.youtube.com/watch?v=HOGQ-HePrT8

I know this works for sure on a motorcycle, and I've tried this experiment on a bicycle too, you can turn a bike right just by pushing the handlebar forward with your right hand. Totally counter intuitive but it works and I'm pretty sure we do it subconsciously when we lean by pushing on the handlebar and we end up counter-steering.

Re: Fresh work on the mathematics of bicycles in motion

#83

Post by randlet » Thu, Jul 21, 2016, 2:06 AM UTC

tome wrote: post #74

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?

I can't help wondering if everyone who has replied to you has mixed up cause and effect. My explanation would be: "To turn left you need to lean to the left. Leaning to the left momentarily forces the handlebars to turn the right." This describes an equivalent outcome to the quotation from the article but implication about what is cause and what is effect is quite different.

It's very easy to verify for yourself that the cause & effect goes "push right handlebar (or equivalently, pull left handlebar) to initiate a right hand turn/lean".

The countersteering argument has been repeated literally 100's of times on the internet on motorcycle forums. It's not worth debating as it is absolutely a real phenomena. It's counterintuitive yes, but there is no doubt that it is real.

Re: Fresh work on the mathematics of bicycles in motion

#84

Post by upofadown » Thu, Jul 21, 2016, 2:19 AM UTC

dahart wrote: post #79

upofadown wrote: post #72

Earlier quoted context omitted.

>and it's important to know in order to stay safe? I disagree with that. Before someone learns to turn a cycle, motorized or not, they have to learn to not fall over. So we tell them that they have to turn towards the direction they are falling. Once they master not falling then in practice there is nothing more to teach. They can easily generalize to adjusting the bike to any lean angle because the required motion o…

It's not my opinion that learning counter-steering is a safety issue, there's a reason that practically all motorcycle safety courses teach it, and that reason is outlined in the Hurt Report on motorcycle safety. https://en.m.wikipedia.org/wiki/Hurt_Report "28. Motorcycle riders in these accidents showed significant collision avoidance problems. Most riders would overbrake and skid the rear wheel, and underbrake the…

If people are not swerving enough then wouldn't we want to teach them to swerve?

I am pretty sure that I have answered your question. It's just a pointless distinction to make. Such pointlessness detracts from actual important lessons. Should we come up with a name for the "oversteering" used to recover from a turn (pro-steering?)? After all, if you don't do it you will be stuck in the turn forever. That would be dangerous.

Re: Fresh work on the mathematics of bicycles in motion

#85

Post by upofadown » Thu, Jul 21, 2016, 2:25 AM UTC

dahart wrote: post #79

upofadown wrote: post #72

Earlier quoted context omitted.

>and it's important to know in order to stay safe? I disagree with that. Before someone learns to turn a cycle, motorized or not, they have to learn to not fall over. So we tell them that they have to turn towards the direction they are falling. Once they master not falling then in practice there is nothing more to teach. They can easily generalize to adjusting the bike to any lean angle because the required motion o…

It's not my opinion that learning counter-steering is a safety issue, there's a reason that practically all motorcycle safety courses teach it, and that reason is outlined in the Hurt Report on motorcycle safety. https://en.m.wikipedia.org/wiki/Hurt_Report "28. Motorcycle riders in these accidents showed significant collision avoidance problems. Most riders would overbrake and skid the rear wheel, and underbrake the…

> that pilots are most definitely taught that pushing forward (up) on the yoke causes the plane to dive (go down),

No, they are taught that pushing forward on the yoke causes the nose of the plane to pitch towards their feet. The result of that depends on the starting attitude of the aircraft. Think inverted flight as an extreme example. In exactly the same way, pushing on the right handlebar has results entirely dependent on the starting attitude of the bike.

Your comment about the roll is correct. That is an effect of a control.

Re: Fresh work on the mathematics of bicycles in motion

#86

Post by exabrial » Thu, Jul 21, 2016, 3:27 AM 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! If you own a motorcycle, you -have- to countersteer!

Re: Fresh work on the mathematics of bicycles in motion

#87

Post by zackify » Thu, Jul 21, 2016, 3:35 AM 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?

Twist of the wrist 2, a movie on how to lean on a motorcycle, explains it really well https://m.youtube.com/watch?v=JWuTcJcqAng

Re: Fresh work on the mathematics of bicycles in motion

#88

Post by dahart » Thu, Jul 21, 2016, 4:55 AM UTC

upofadown wrote: post #84

dahart wrote: post #79

Earlier quoted context omitted.

It's not my opinion that learning counter-steering is a safety issue, there's a reason that practically all motorcycle safety courses teach it, and that reason is outlined in the Hurt Report on motorcycle safety. https://en.m.wikipedia.org/wiki/Hurt_Report "28. Motorcycle riders in these accidents showed significant collision avoidance problems. Most riders would overbrake and skid the rear wheel, and underbrake the…

If people are not swerving enough then wouldn't we want to teach them to swerve? I am pretty sure that I have answered your question. It's just a pointless distinction to make. Such pointlessness detracts from actual important lessons. Should we come up with a name for the "oversteering" used to recover from a turn (pro-steering?)? After all, if you don't do it you will be stuck in the turn forever. That would be dan…

> Should we come up with a name for the "oversteering" used to recover from a turn

Ignoring the reductio ad absurdum, then if you're referring to how you have to steer the handlebars further into a turn in order to straighten out, there is a name for that: counter-steering. :)

Re: Fresh work on the mathematics of bicycles in motion

#89

Post by stedalus » Thu, Jul 21, 2016, 5:16 AM UTC

theOnliest wrote: post #64

davidw wrote: post #54

Earlier quoted context omitted.

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)

And Ilnur Zakarin (also from today's stage) showing how others aren't as good! Starting at about 2:00 in: http://www.dailymotion.com/video/x4l18sa_flamme-rouge-etape-...

To be fair to Zakarin, the finish is substantially steeper than the section Peter was on, and he had just spent the 30 minutes on the rivet to get the stage win.

Re: Fresh work on the mathematics of bicycles in motion

#90

Post by stouset » Thu, Jul 21, 2016, 7:04 AM UTC

no_flags wrote: post #62

kqr wrote: post #18

Earlier quoted context omitted.

Ever thought about why you can't "steer away" from a curb, how it appears to "suck you in" when you try? It's because that first, subconscious turn in the wrong direction takes you into the curb edge.

I've heard this was more of a psychological "target fixation" effect, unless I misunderstand the scenario you describe.

You heard wrong. It's because you can't countersteer, which is the only way to turn a bicycle or motorcycle at speed.

Try it. Get on a bike. Go straight, and pick up speed. Intentionally press the right side of the handlebar. Note which direction the bike is now aiming.