A bird's-eye view of sport, translated by two humans. With added waffling.

Tuesday 7 August 2012

A quick guide to keirin racing

We've reached the final day of competition at the velodrome, and there are still medals up for grabs in the men's keirin, women's sprint and women's omnium events.  Victoria Pendleton is chasing her second gold medal of these Games and has reached the semi-final stage of her quest to retain her Olympic sprint title - you can still find our handy guide to the sprint here.  Meanwhile, world and Olympic champion Sir Chris Hoy is the favourite for the keirin and has safely qualified for the second round.  We've dug up and dusted off our hypothetical moron to help explain the finer points of the keirin for you.

Hello again!  I've really enjoyed watching all these British stars at the velodrome, and I saw Victoria Pendleton win the women's keirin a few days ago.  Not for the first time, I didn't have a clue what was happening.  Help!

OK, calm down!  What do you want to know?

Well, what does keirin mean, for starters?  I think I drank a beer called keirin once.  Is it named after that?  Do they all get drunk first?

Keirin just means "racing wheels" in Japanese.  The beer is called Kirin, and it's named after some kind of mythical deer-dragon-unicorn chimaera.  Racing wheels.   Mythical deer-dragon-unicorn chimaera.  Racing wheels.  Mythical deer-dragon-unicorn chimaera.  Two different things.  Got it?

I think so.  But if it's a Japanese pastime, where are the teenage girls and the octopus?

Er.  Yes.  I'm not sure.  If it helps, you can imagine them watching excitedly from the stands.

Oh, it does help, trust me.  *awkward pause*  So... what's the basic set-up in a keirin race?

The race lasts eight laps or 2,000 metres, and the winner is the rider who crosses the finish line first.  On the start line, six riders line up across the track in positions determined by drawing lots.  As the starting gun fires a motorized pacing bike called a Derny rides past the start line at a speed of 30km/h, and the riders set off and form a straight line behind it.  The Derny gradually increases the pace until it reaches its top speed of 50km/h, and pulls off the track with about 600 metres to go.

It might help to think of a keirin race as being divided into two separate phases.  In the first phase, the riders line up behind the Derny and try to secure the best position to apply their chosen tactics for the final sprint.  In the second phase, the Derny pulls off and the riders start to sprint for the finish line.

How does the first phase of the race work then?  Can the riders overtake the Derny?

The riders can't overtake the Derny, but they can overtake each other.  The positions of the riders in the line behind the Derny will primarily be determined by any extra acceleration that they decide to apply in riding away from the start line.  Once the riders have lined up behind the Derny, it's quite difficult (but by no means impossible) to overtake another rider without doing so dangerously and breaking the rules.  Trying and failing to overtake could also mean that the rider ends up further back down the line than they started as gaps are quickly closed by the other riders.  Riders will often leave little gaps in the line to give themselves more room for manoeuvre (so they can respond to attacks from behind or put more effort into their own attacks later in the race), but any such gap cannot exceed 10 metres.  Most riders prefer to ride in the first few places behind the Derny, but Chris Hoy for one has consistently shown that keirin races can be won from anywhere.  The tension slowly builds as the pace of the Derny increases, and reaches a crescendo as it pulls off the track.

How does the race change when the Derny pulls off?

Once the Derny pulls off, the proper racing begins and the riders sprint for the finish line.  There are two main dangers that the riders will be keen to avoid.  The first is getting stuck on the inside of the track surrounded by other riders and not being able to start their final sprint at the crucial moment.  The second is getting stuck at the back of the pack and being forced to take a longer route around the other riders.  At these speeds, either problem could cost a rider any chance of winning a medal, so careful positioning is vital.

Does that mean that the best strategy is to ride immediately behind the Derny and start sprinting flat out as soon as the Derny leaves?

Not necessarily, no.  Some riders with better sprint endurance than their rivals might try this - Chris Hoy might well do so tonight.  However, as we explained for the sprint event (and as Anna Meares showed in the women's keirin final), this is a high-risk approach as the rider creates a slipstream which their rivals could use to launch an attack if they can catch up.   Just like the sprint, there's no one-size-fits-all strategy that will always work best.  No rider would use the same strategy for every race, not least because their rivals would know exactly what to expect.

Could we see thrills and spills?  I like thrills and spills!

In a word, YES.  With six sprinters jockeying for position at up to 75km/h on a sloped track, it's not surprising that crashes, relegations and disqualifications are very common in keirin racing.  The riders will often be forced to use their shoulders and elbows to defend their position, and the slightest touch of wheels could unceremoniously scatter the whole field across the track.  It's a much more physical event than you might expect, and anything can happen.

Chris Hoy is by no means guaranteed to stay upright, let alone to win his record-breaking sixth Olympic gold.  If we had fingers, we'd be crossing them hard.  But if all goes to plan, Britain might well end the day with a staggering total of eight golds from ten track cycling events.

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