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Fresh work on the mathematics of bicycles in motion

nature.com

21–30 of 100 posts

Re: Fresh work on the mathematics of bicycles in motion

#21

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.

See Murata's Robots: http://www.murata.com/en-us/about/mboymgirl

Re: Fresh work on the mathematics of bicycles in motion

#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 feature, or if time will show the current design is the best.

Re: Fresh work on the mathematics of bicycles in motion

#23
post #19
post #14

Earlier quoted context omitted.

Yes! This PDF explains it very well, with illustrations, on the last page: http://bicycle.tudelft.nl/schwab/Bicycle/DO-07-3-2bicycles.p... "Practically nobody is conscious of the fact that they must steer briefly to the left ion order to make a right-hand turn. But this is not so strange, because the swerve is very small (approximately 3 degrees) and happens very quickly – 0.5 seconds. The wet tire tracks from cyclin…

It seems that they are saying you have to steer right in order to initiate a left lean. But how do they account for steering with no hands? I can steer pretty well without hands. It seems as if I must be able to initiate the left lean without pushing the handlebars right. So why couldn't I also do this when not riding without hands?

I can ride pretty well without hands as well. When I heard about counter-steering a long time back I paid closer attention to what I was doing while riding hands-free. Turns out that I was doing a weird little bodily flick motion in to get the wheel pointing to the opposite direction of the turn before I started leaning into the turn.

Pay attention to yourself next time you ride and you might be surprised.

Re: Fresh work on the mathematics of bicycles in motion

#24
post #20

OK - this is probably my ignorance talking, but why is it surprising that bike are balanced? The pedals are basically shoulder width and staggered, which is a very natural position for people to balance in as bipedal creatures? in addition, while the bike is moving, won't the inertia tend to keep things moving in the same direction? This is all coupled by the fact that the rider is actively piloting and adjusting the…

bikes are balanced without a person on them

Re: Fresh work on the mathematics of bicycles in motion

#25
post #20

OK - this is probably my ignorance talking, but why is it surprising that bike are balanced? The pedals are basically shoulder width and staggered, which is a very natural position for people to balance in as bipedal creatures? in addition, while the bike is moving, won't the inertia tend to keep things moving in the same direction? This is all coupled by the fact that the rider is actively piloting and adjusting the…

[deleted]

Re: Fresh work on the mathematics of bicycles in motion

#26
post #19
post #14

Earlier quoted context omitted.

Yes! This PDF explains it very well, with illustrations, on the last page: http://bicycle.tudelft.nl/schwab/Bicycle/DO-07-3-2bicycles.p... "Practically nobody is conscious of the fact that they must steer briefly to the left ion order to make a right-hand turn. But this is not so strange, because the swerve is very small (approximately 3 degrees) and happens very quickly – 0.5 seconds. The wet tire tracks from cyclin…

It seems that they are saying you have to steer right in order to initiate a left lean. But how do they account for steering with no hands? I can steer pretty well without hands. It seems as if I must be able to initiate the left lean without pushing the handlebars right. So why couldn't I also do this when not riding without hands?

You can, I think both were described in the theory book for notorcycle license when I glanced through it.

Fun fact: when I read about it I had to test and I had to make sure I wasn't deceiving myself so I put one palm in front of the handle on one side and the other one behind the handle on the other side. That way I could ensure I pushed it the correct way.

It worked exactly as advertised (50cc bike so somewhere below 60km/h).

Much simpler than using slow motion camera etc.

Re: Fresh work on the mathematics of bicycles in motion

#27

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.

See Murata's Robots: http://www.murata.com/en-us/about/mboymgirl

That's cool, but the robot there needs a large gyro stabilizer disc to keep balance. Not exactly the way we do it.

Re: Fresh work on the mathematics of bicycles in motion

#28
post #19
post #14

Earlier quoted context omitted.

Yes! This PDF explains it very well, with illustrations, on the last page: http://bicycle.tudelft.nl/schwab/Bicycle/DO-07-3-2bicycles.p... "Practically nobody is conscious of the fact that they must steer briefly to the left ion order to make a right-hand turn. But this is not so strange, because the swerve is very small (approximately 3 degrees) and happens very quickly – 0.5 seconds. The wet tire tracks from cyclin…

It seems that they are saying you have to steer right in order to initiate a left lean. But how do they account for steering with no hands? I can steer pretty well without hands. It seems as if I must be able to initiate the left lean without pushing the handlebars right. So why couldn't I also do this when not riding without hands?

There's a really cool video demonstrating the idea [0]. They took a set of handlebars and welded them to the frame. You'll see that you can affect a motorcycle, but only poorly. On a bicycle, you're much more top heavy and can force the vehicle to capsize far faster. On my motorcycle though? If I lightly increase the throttle it'll go absolutely straight (which is nice if you need to reseat your gloves, but scary if the road starts to veer to the side!)

[0] https://www.youtube.com/watch?v=4PbmXxwKbmA

Re: Fresh work on the mathematics of bicycles in motion

#29
post #20

OK - this is probably my ignorance talking, but why is it surprising that bike are balanced? The pedals are basically shoulder width and staggered, which is a very natural position for people to balance in as bipedal creatures? in addition, while the bike is moving, won't the inertia tend to keep things moving in the same direction? This is all coupled by the fact that the rider is actively piloting and adjusting the…

Bike are balanced and symmetric side-to-side. Top to bottom they are not, obviously. The center of mass is above the ground , so a bike that is not moving will fall over to lower its center of mass. But this doesn't happen if the bike is moving. Push a bike without a rider and it will travel for a few feet without falling over, and take longer to fall over if just left standing still.

Re: Fresh work on the mathematics of bicycles in motion

#30
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?

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.

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