Look Ma, no hands....

open topic, for anything cycling related.

Look Ma, no hands....

Postby il padrone » Sat Dec 14, 2013 5:46 pm

Riding bikes in traffic - what seems dangerous is usually safe; what seems safe is often more dangerous.
User avatar
il padrone
 
Posts: 18297
Joined: Mon Apr 07, 2008 11:57 pm
Location: Heading for home.

by BNA » Sat Dec 14, 2013 8:23 pm

BNA
 

Re: Look Ma, no hands....

Postby ColinOldnCranky » Sat Dec 14, 2013 8:23 pm

Very interesting. I concluded most of it myself as many will have done. Though I had not though much about trail and interpreted the typical design differently, but I concede the error.

I am not too pleased with some of his later explanations - I think he may have been stretching a bit.

For example, being able to ride a contraption in side two minutes could be for any number of reasons I'd guess.

I don't think that riding his contraption within two minutes demonstrates doing anything remarkably difficult. And therefore is no indication of any inherent stability. I venture that I could design an unstable product that people with an appropriate skill set could also manage very quickly.

Sidebar:
I have. over recent years, put around 30 or 40 unicyclists of ALL abilities (or disabilities :mrgreen: ) onto a giraffe, those tall chain-drive unicycles that performers like to show off on. My record so far is that almost every rider has cycled away from support and a balancing shoulder on the first or second attempt.

A few have taken a third attempt. No one has failed to ride away in control within three attempts.

I repeat NO-ONE has failed to ride away in control within three attempts.

Nevertheless, the physics and geometry is very interesting and I will certainly be using this TED talk to challenge others claiming that it is all about rotational inertia.

I'd love to see someone now tackle the belief that the crack of a whip is a sonic boom. (Yes, I am aware of the much quoted mathematical treatise that was done a few years back but I can also demonstrate where why the learned authorr is wrong.)
Unchain yourself - Ride a unicycle .Image
User avatar
ColinOldnCranky
 
Posts: 4695
Joined: Fri Feb 27, 2009 3:58 pm

Re: Look Ma, no hands....

Postby ausrandoman » Sat Dec 14, 2013 8:38 pm

Wait here. The peanut gallery who wouldn't know a holonomic constraint if they sat on one will be along to comment soon.
ausrandoman
 
Posts: 609
Joined: Fri Apr 03, 2009 7:33 pm

Re: Look Ma, no hands....

Postby il padrone » Sat Dec 14, 2013 9:21 pm

ColinOldnCranky wrote:I don't think that riding his contraption within two minutes demonstrates doing anything remarkably difficult. And therefore is no indication of any inherent stability.

I think that was his point. The easy skill acquisition indicates that it is not dificult. Hence the bicycle is relatively stable. An unstable bike would be much more difficult and take much more time to master.



ColinOldnCranky wrote:I venture that I could design an unstable product that people with an appropriate skill set could also manage very quickly.

I've seen one of those - a guy down on Southbank, busking with a bike that had designed-in reverse steering - turn left and the front wheel turns right. No-one that I saw could ride it more than about 0.5m. But the guy who owned it had mastered the skill. Which I think was basically to ride with as little input to the steering as possible - just let the bike steer itself.


So I guess the bike was actually stable, just not when anyone tried to steer it. :oops:


And I have never sat on a holonomic constraint, as far as I know.
Riding bikes in traffic - what seems dangerous is usually safe; what seems safe is often more dangerous.
User avatar
il padrone
 
Posts: 18297
Joined: Mon Apr 07, 2008 11:57 pm
Location: Heading for home.

Re: Look Ma, no hands....

Postby ColinOldnCranky » Sun Dec 15, 2013 2:03 am

il padrone wrote:
ColinOldnCranky wrote:I don't think that riding his contraption within two minutes demonstrates doing anything remarkably difficult. And therefore is no indication of any inherent stability.

I think that was his point. The easy skill acquisition indicates that it is not dificult. Hence the bicycle is relatively stable. An unstable bike would be much more difficult and take much more time to master.

That is his argument but it does not mean stability. Perhaps it is fair to say it is not chaotic in a mathematical sense, not much more. There is nothing stable about a giraffe unicycle, far from it yet it follows from his interpretation that a giraffe is stable. It is a stretch when his otherwise reliance on solid principles stand on their own anyway. Best to have left it unsaid.

But I don't wish to detract from a very informative talk. This has been added to my links that I like to revisit from time to time.

I prefer not to sit on holonomic constraints. They irritate my hemorrhoids.
Unchain yourself - Ride a unicycle .Image
User avatar
ColinOldnCranky
 
Posts: 4695
Joined: Fri Feb 27, 2009 3:58 pm


Return to General discussion

Who is online

Users browsing this forum: LG, Percrime, rheicel



Popular Bike Shops
Torpedo 7 Torpedo7 AU
Ground Effect Ground Effect NZ
Chain Reaction Cycles CRC UK
Wiggle Wiggle UK
Ebay Ebay AU

“Bicycles BNA Twitter
“Bicycles BNA Facebook
“Google+ BNA Google+
“Bicycles BNA Newsletter

> FREE BNA Stickers
> BNA Cycling Kit