Dylan Cleaver: Rub of a rail can take golden moment away

In the aftermath of that dropped rail, the clip of the hooves that turned gold to silver, it suddenly dawned: equestrian delivers a uniquely complex sporting drama.

As Sweden's Sara Algotsson Ostholt approached the last fence, gold was in her grasp. Her mount, Wega, had been near flawless over the three disciplines of dressage, cross country and jumping. There was no reason to doubt they would falter now.

Up she went, there was a noise as hooves clipped rail, the crowd "oohed" in unison, but the rail stayed put. Or did it? After what seemed like an eternity - but was probably half a second - the wobble became a topple. Considering that you could have heard a pin drop, the noise of a rail crashing to earth resonated around the stadium like the opening bars of Start Me Up.

Three days in the saddle and it came down to that.

Equestrian is not alone in providing photo finishes, nerve-shredding finales and triumph and despair. But it is alone in providing it on such a broad canvas.

For starters, the relationship between man and beast is, obviously, pivotal.

"With a young horse it is about learning to deal with pressure and this Olympics came a year too early for [Campino], said legendary horseman Mark Todd of his mount.

He could have been talking about less experienced teammates, too, like Jock Paget and Jonelle Richards, who were good, but will be even better in Rio.

There's the gender issue in the fact there is no gender issue. Men and women compete on an even plane and, by and large, without any prejudices. They don't need farcical mixed doubles formats to appear on the same stage.

Then there's the whole issue of class.

There's a lot of money and a lot of Range Rovers in this sport. There are beautifully clipped vowels and expensive "casual" wear. But there was also Paget, a former Sydney bricklayer who went to rodeo school, sharing the spotlight with a granddaughter of the Queen.

Okay, egalitarian might not be a word that springs to mind when discussing equestrian, but it's not the exclusive domain of the sons and daughters of landed gentry either.

This heady brew would be nothing without the sport providing a compelling narrative.

If one dressage looks like any other to you, you're not alone. It might be described as "the highest expression of horse training", by equestrian officials, but to the layman it looks like horses prancing around in a box. But you don't need to know your fetlocks from your flanks to know what the score is in the cross country and jumping phases. The sight of horses thundering through the park leaping fences and other more contrived obstacles is nothing short of exhilarating.

New Zealanders seem to love this phase more than any other and you can see why - it appeals to our sense of adventure.

The jumping phase is more choreographed, but no less exciting. Watch the crowd. When the horses leap, they subconsciously raise their shoulders too, as if they can will the horse over with body language.

When the riders and horses are this good, millimetres make a huge difference.

"As you saw today," said Todd, "it can change with just a rub of a rail."

And it did.