Copenhagen WC keirin 09

[Simon Llewellyn]

Check out this Keirin...

http://www.youtube.com/watch?v=MedBqoFPv-o

[mikesbytes]

Ouch

[timyone]

man thats crazy! has every thing?@
check out the boxing!!

[Toff]

Ouch. I'm at work so I won't be able to hear if there's any sound (commentary) until I get home, but oooouchh!

I love how 3 technicians in black come over and head straight for the bikes, not the riders. They get straight to work on the hardwear while the riders just lie there!

[weiyun]

I love how 3 technicians in black come over and head straight for the bikes, not the riders. They get straight to work on the hardwear while the riders just lie there!

They are not medics. Their assistance to the riders may become a legal liability should anything goes wrong.

[wallman]

I thought for a big fella Hoy went down pretty easily...

[Simon Llewellyn]

I thought for a big fella Hoy went down pretty easily...

Yeah it is strange isn't it? There's a general vibe that five spokes aren't as stable as some of their predecessors which is a kind of myth but has some evidence behind it or video proof. I can only assume Hoy was on 19mm tyres with probably 200PSI or something in that region because he does seem to have much tyre surface area. I can tell you that 5 spokes do feel considerably different to a normal spoked wheel but they're very stable.

[Toff]

Hoy gets a knock from the guy above him before he goes down. On the flat it wouldn't have mattered, but on the sloping track it translated into additional sideways force on the tyre, and over he goes. One thing it does demonstrate is how remarkably stiff those frames are, that a knock can transmit itself down through Hoy and his frame so effectively. I guess that means that Hoy himself was also very rigid: no fat to dissipate the impact!

[Toff]

Actually, looking at it again, I'd say Hoy is a victim of his own Shennanigans. The rider above him is going past him, and will leave him boxed in, so Hoy leans up and into the rider above him, instead of waiting to go round. His weight is transferred to the far right of his bike. This puts extra demands on his front wheel. The other rider leans back, putting even more pressure on his front wheel, which is already leaning on a negatively cambered track. If your front wheel hits a drop of sweat on the track under those loads, the result is inevitable!

[weiyun]

...which is already leaning on a negatively cambered track.

I didn't think there's one inch of negatively cambered track in a velodrome.

[Toff]

I didn't think there's one inch of negatively cambered track in a velodrome.

Probably my fault with somewhat casual use of the word camber. A better word would be "cant", or just "slope". As the cyclist rides around the track, the cant of the track would be neutral if the shearing loads at the wheel were 0 N. If the rider is going fast enough, then the centrifugal forces will exceed the gravitational forces, resulting in a desire for the tyre to slip out up the track. If the rider is going slowly (or if the rider's turning radius is reduced, such as on the straight sections of the track) then the gravitational load on the tyre is greater than the centrifugal load, and the wheel tends to want to slip out down the track. This situation, where, all other things being equal the tyre wants to slip out downward is what I referred to as negative camber. I probably could just as easily have said:

"...putting even more pressure on his front wheel, which is already leaning on a downward sloping track."

[weiyun]

Don't worry Toff, I was nit picking.

[Trouty]

That's an expensive little accident. I didn't know there was so much contact allowed in this race.