Kersten sets 80kmh velodrome record

Triathlon Forum
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This is from this mornings Sydney Morning Herald:

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As Ben Kersten hurtled into the third bend of the velodrome in his attempt to reach a record speed of 80kmh yesterday, the heart rate of his trainer accelerated accordingly.

But it was not the record attempt troubling Gary Sutton - Kersten had already cracked that milliseconds earlier - rather his charge’s ability to stay upright under the weight of the G-force.

Sutton knew Kersten’s wheels would be shaking as he sat in the slipstream of a motorbike on a light fibre bike in the Dunc Gray Velodrome, with only about half a centimetre of tyre surface on the track.

He knew Kersten’s front wheel would give way first and that the injuries if he fell could end his career, and maybe worse.

It had been depriving him of sleep.

“I’ve been worried about it at night even, because Ben is one of these guys who wouldn’t back off,” Sutton said. "I said to him at the start, ‘I don’t like talking negative but safety first. If you need to bail out, bail out’.

"To get up to those speeds coming into the bend, the chances of coming out are very limited.

“My concern was that he might end up just crashing into the bend.”
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Sutton need not have worried.

Kersten screamed into the final turn, then pulled out, looping high around the motorcycle pacer and winding down his pace.

He had reached a top of 84kmh and was officially clocked at 80.3kmh.

“My biggest fear was coming out of the bend,” Kersten said.

“When you go round a bend your speed goes up one or two kilometres an hour and I was at maximum speed so I had to pull the plug.”

The velodrome has a maximum speed limit of 87kmh, after which the cyclist will become airborne.

The last person to set a speed record there was Sutton’s son, Chris, who clocked 75kmh in February.

**

Can anybody explain the airborne part of it? is this fairdinkum?

2

As I understand it, you will start to slide out if you go over the max. Your back wheel will slide up track as you get into a corner. I don’t think you will go airborne, just fall down, hard.

3

I don’t know about getting airborne, but if the cyclist can get up to 88 mph whilst generating 1.21 gigawatts of power, and he has remembered to attach a flux capacitor to his bike, he can go back to the future.

4

Your center of mass shifts from above the wheel contact patch, to the far left of the contact patch. The faster you go, the farther your center of mass shifts in the turns as you begin to lean past 90 degrees to the surface, which is banked up to 51 degrees on some tracks. Going from 2.5 Gs in the turns back to 1g really unweights the back end as well.

The Forest City Velodrome in London, Ontario has that sensation when you exit turn 4 high. Your bike “unloads” as if travels down from the top of the 50 degree banking to the 14 degree straights.

forestcityvelodrome.ca

-SD

5

It’s a silly record when he is following a motorbike - who cares?

What’s the real record speed on a velodrome?

6

Resurrect.

I went to visit the VeloDrome in London when I was there over Christmas and had a chat with Rob Good. I really wish I had brought my cycling gear with me when I was there as I REALLY wanted to try out the track. They had a youth program running when I visited.

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Resurrect.

I went to visit the VeloDrome in London when I was there over Christmas and had a chat with Rob Good. I really wish I had brought my cycling gear with me when I was there as I REALLY wanted to try out the track. They had a youth program running when I visited.

Rob’s a great guy and really good for that program. He’ll put aside his own time to devote to juniors and novice riders. Glad to hear the track is still attracting people. The idea of having a somewhat warm place to train is probably enticing in London, ONT!

-SD

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He seemed really good with the kids that were there taking part in the program. He knew all of them by name and seemed to spend time with each of them regardless of skill level and the amount of time that was needed. Considering I am from Ottawa, which is even colder than London, yes it is nice to have a place to go to train aside from an indoor trainer.

Next time I am in town I am definitely going prepared.

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Hamilton was supposed to be getting the PanAM velodrome but now it appears someone else will be building it instead. Which sucks…I was looking forward to having something quality bicycle related in this city. I thought we were on the right track having hosted the World road here but council doesn’t seem to remember that.

10

Nice resurrection.
I had no idea that London has a track. Do they have bikes on site that you can plug pedals into? Would be a lot of fun for the occasional work trips to London, thanks for bumping this back up.

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Too bad. That would have been really cool for both spectating and participating.

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Edit: Never post quickly from a busy coffee shop – you end up looking like an idiot. Thanks to MTM for correcting some really incorrect stuff. I made the edits, below, so everything’s ok now.

Some things to know about velodrome riding:

  1. The centre-of-gravity travels 2-5% slower than the wheels in the turns.

  2. Lean angles are approximately atan( v^2 / (g*r) ),
    where g=9.80655 m/s^2,
    v is the CG velocity,
    r is the turn radius

For a 20-25m turn radius at speed, that comes out to over 42 degrees.

  1. CG height can drop (into turns) and rise (out of turns) by 0.3m or more.

  2. Because of 3), the CG picks up speed in the turns, as potential energy is converted to kinetic energy. Needless to say, the wheels spin even faster!

So I would say that on the exit of the turn, the CG’s trajectory has the wheels leaving the ground. Not a really good thing, I would think.

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  1. The centre-of-gravity travels 2-5% faster than the wheels in the turns.

Thanks for the facts, Andy. But doesn’t the wheels travel faster than the center of gravity in the turns? I’m no velodrome expert, but I would think the center of gravity would be closer to the center of the velodrome hence travelling slower. Maybe I’m missing something?

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I think what Andy is getting at, and I am purely basing this on my understanding of the info he provided, is that the G forces actually move a riders center of gravity as they go through the turns of the track.

As mentioned above, the track that the speed record was done on had a MAX speed of 87km/h as the rider would actually get airborn at that speed. I am guessing that phenomenon is due to the motion of the CG. Am I right?

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Hamilton was supposed to be getting the PanAM velodrome but now it appears someone else will be building it instead. Which sucks…I was looking forward to having something quality bicycle related in this city. I thought we were on the right track having hosted the World road here but council doesn’t seem to remember that.

latest news i’ve heard is that it will be built in milton - on my way home from work!

vandrunken, it’s a pity you missed out - my husband and i did the track 1 session in mar/11, and it’s a riot! rob is an excellent instructor, though i did hurl some less than complimentary language in his direction when he made us do standing laps; the g forces in the turns don’t mess about! i did apologize afterward.

yes, FCV does have bike you can rent and just throw on your pedals. they do ask that you do the track 1 (introductory) course before showing up for a rec. ride, though. the website has all kinds of useful info.

cheers!

-mistress k

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  1. The centre-of-gravity travels 2-5% faster than the wheels in the turns.

Thanks for the facts, Andy. But doesn’t the wheels travel faster than the center of gravity in the turns? I’m no velodrome expert, but I would think the center of gravity would be closer to the center of the velodrome hence travelling slower. Maybe I’m missing something?

No, I’m just an idiot. I posted quickly from a busy coffee shop and “slower” turned into “faster”, somehow. And then it was all downhill after that. Thanks for the catching this. I made the edits in the post.

Cheers,

Andy

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Good to know, thank you. Lucky you to have a track on your commute!

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Thanks for the explanation Andy.

Ive ridden the Dunc Gray velodrome plenty of this past winter and even a hack like me picks up considerable speed in the heavily banked turns (42 degrees), but at my speeds, you are simply glued harder to the track the faster you go.
Once you learn to ride the bank, its lots of free speed and plenty of races are won or lost on the last turn.