Youtube thread

[Psycholist]

The spokes that ping are the ones that point to the ground as with high loads they lose enough tension that the friction force between the nipple and the rim is reduced enough to allow the spoke to untwist. The rest of the spokes see a slight tension increase (Approximately equal to the tension lost in the bottom spoke divided by the number of spokes remaining).

[neil_]

Cormac, I await your thoughts on this
http://caronbicycle.com/

[Psycholist]

Looks like another bicycle designed by people who don't ride bicycles. Looks like they added another two freewheels to the system to allow both pedals to independently drive the chain. Only downside is it never occurred to them that when you stand on the pedals having both pedals go to bottom dead centre so you can't leave the saddle properly for bumps is not a desirable behaviour...

Possibly dumber than the guy who added a drive between the handlebars and the pedals so that you could drive the bike by pivoting the bars up and down. It never occurred to him that the bars are already transferring exactly this force to the pedals on a standard bike when you stand up and pedal...

[Joejoebeans]

It looks like it was designed to make cycling as difficult as possible. I imagine it would be great for your core because of the extra effort involved in pulling your legs back up instead of using the momentum to just keep swinging them around

[neil_]

I said Cormac, not Joe

[Chimaera]

Interesting discussion of helmet safety: https://www.sciencebasedmedicine.org/do ... -injuries/

[John]

Chris Harris with some more car porn, NSFW
https://www.youtube.com/watch?v=-hTLk1rU_ZI

[nathybren]

Chris Harris with some more car porn, NSFW
https://www.youtube.com/watch?v=-hTLk1rU_ZI

My word that man can drive.
He sounded like he was gonna lose a load in his pants on the track.
He upsets the status quo here and actually makes me want a Porsche.

[Psycholist]

Especially the Spy Hard one
http://www.merlincycles.com/blog/hollyw ... ng-scenes/

[Psycholist]

Brian Lopes goes fast: http://www.vitalmtb.com/videos/features ... =spotlight

[neil_]

http://phys.org/news/2015-05-maths-cong ... affic.html

Mildly interesting in an unrepentantly nerdy manner. Improving the efficiency of a part of a network can decrease the efficiency of the whole network in some circumstances.

[Joejoebeans]

https://www.facebook.com/permalink.php? ... 37&fref=nf

Well shit...

[Psycholist]

It's not clear whether they mean the tech trails they've put in or all the stuff further up the mountains not put in by Coillte. I don't know 16 trails that aren't Coillte built around the Ballyhouras anyway, but then again it's too much driving there and back to justify going exploring and risk not getting a decent spin at the end of it. Also chances are the Seefin route will remain since it's been there as a fire road/walking trail far longer than the MTB trails.

[Joejoebeans]

Some of the GE route put you on built sections and fireroad sections. I imagine they're counting anything with a gap like that as an individual trail. Not sure if that adds up to 16 either mind you but that's all I can think of.

Think there are only ~5 tech trails there but I could be totally wrong on that. That's just based on what I can remember cycling past while doing the extended brown loop

[Psycholist]

Ali C in Barcelona: https://www.youtube.com/watch?v=wGRjmDHFUZQ

[Joejoebeans]

https://www.youtube.com/watch?v=qUOasoDcIiU

Hadn't heard of this guy before. He's got some style. Skip to about 1.00 to avoid the "art"

[FartingFury-]

https://www.youtube.com/watch?v=qUOasoDcIiU
Hadn't heard of this guy before. He's got some style. Skip to about 1.00 to avoid the "art"

@ 5:00 is just impossible!

[Psycholist]

Ryan Leech was riding slack chains between bollards over 10 years ago in his Manifesto video, so a tensioned cable is less of a challenge, though the chance of nasty injuries is higher with the tensioned cable because it's higher up...
Chain riding is at 16:20 here: https://www.youtube.com/watch?v=ZwEbZ6bzlVk

Here's some street and jumps on the world's first production 24" wheeled fatbike: https://www.youtube.com/watch?v=EygF8Cu4hj4

[Joejoebeans]

I think it's the fact that it's so narrow that's impressive. Not that that hasn't been done before either but it's still cool

[neil_]

Ryan Leech was riding slack chains between bollards over 10 years ago in his Manifesto video, so a tensioned cable is less of a challenge, though the chance of nasty injuries is higher with the tensioned cable because it's higher up...
Chain riding is at 16:20 here: https://www.youtube.com/watch?v=ZwEbZ6bzlVk

Here's some street and jumps on the world's first production 24" wheeled fatbike: https://www.youtube.com/watch?v=EygF8Cu4hj4

The cable has less inertia and a wobbles at a higher frequency than the chain, and it's narrower. It looks more difficult to me - not that I'm an expert or anything.

[Psycholist]

The chain doesn't have a consistent contact point with the tyres and can roll out from under the tyres thanks to there being no contact point on the centroid of the chain for the tyre. Tensioned wire is probably easier to balance on because of it's higher resonant frequency. The rider's weight has a lot less time to fall to one side as the cable moves offline thanks to it centering itself more quickly. I also vaguely recall an MBUK article mentioning that Martyn Ashton had ridden a slack chain between bollards in the late '90s come to think of it. I should mention that just because there's nothing in it that I haven't seen done before or better elsewhere, the video that Joe linked remains very classy indeed ...

[Psycholist]

Speaking of classy: http://gfycat.com/LiveLeadingCrocodile

[FartingFury-]

Interesting beginner-level article on bicycle geometry: http://www.economist.com/news/science-a ... wer-uphill (does take a while to get going though).

[Psycholist]

There's a better article describing the same experimental results further back this thread I think - with videos ...
Here's one: https://www.youtube.com/watch?v=YdtE3aIUhbU
The summary is that if the bike turns in the direction it's falling then it can be self stable. Moving contact patch between the wheel and the ground may well be the only force left to steer the bike shown in the video, though it does look like there's a good bit if weight in front of the front axle on the front forks to cause steering due to gravity as the bike leans.

The South Koreans have won the DARPA robotics challenge too: http://www.industrytap.com/south-korean ... 5-40446113

The video at the end of the article shows why we don't need to be frightened of being overrun by robots just yet . The average drunk person is currently doing better than state of the art AI for balancing bipeds...

The really interesting thing is that some of the falls look remarkably human, so at least part of the feedback control they're using does appear to be similar to what humans programs themselves to do through trial and error.

[Psycholist]

Pogo... https://www.indiegogo.com/projects/v4-t ... ick#/story

Here's some concrete that repairs itself: http://interestingengineering.com/tu-de ... oconcrete/