With a fast start the priority, riders require the full use of their limbs to propel their bikes, weighing less than 10kg, out of the starting gate at speed.
Sarah Walker, however, broke her right arm four weeks ago. She was still wearing a heavy brace yesterday and, after a month of limited activity, managed to complete a full array of jumps only on Wednesday.
The start is where she feels the most pain. The fracture she suffered to her radius still protests when Walker pulls herself from the top of the ramp, attempting to accrue maximum downward momentum, aching to get to that first corner in front.
The pain will not prevent Walker from riding in the elite women's field at this weekend's world championships at Auckland's Vector Arena. After all, the face of BMX in this country was not going to let a minor malady like a broken arm prevent her from racing in front of her home fans.
But she can't make any promises about her performance - her arm made sure of that, leaving the 25-year-old just as curious as the crowd.
"I don't actually know [of my prospects]. I wouldn't have a clue," she said. "I know there's a bit of expectation for me to just jump on my bike and win. Anything is possible, but I doubt it's going to happen. All I can do is give the best performance I can."
The lowered expectations are understandable, given Walker's abridged preparation, and they're only reinforced by her inhibition at the start line.
"The tricky part for me is going to be out of the start - that's where I seem to have the most pain," she said. "But I don't think I'll have doubt in my mind - all I can do is get the best start I can with what I'm given. If that means I'm out the back, then that's what it is.
"I just want to give the best start I can and I really don't know where that's going to put me at the moment."
Even if it fails to put her on the podium, Walker's mere participation is in itself a boon for the event. Her personable nature, combined with world championship gold in 2009 and Olympic silver in 2012, makes Walker an ideal ambassador for BMX in New Zealand
She already has a direct influence on a new generation in the relatively young sport; Jessie Smith, who won the girls' 12-years age group on Wednesday, credited her mentor for her success, saying Walker was her "biggest fan".
Walker's figurehead role played a part in her determination that, after she landed heavily at the United States nationals in Illinois last month, she would make minute improvements every day of her recovery, designed to culminate this weekend.
"I'm feeling a lot more confident than I did even a couple of days ago," she said. "One day is such a large amount of time in the big scheme of things for me.
"Two days is a huge amount of time, so I'm glad I've still got two days until we're actually racing."
Walker said recently she would have probably skipped the event were it not for the lure of a partisan crowd, but competing in her home country provided more than just motivation in her search for full fitness.
"I've been literally counting down every single day to be on my bike. If it had been anywhere else in the world we would have left by now, yet yesterday I was still learning new jumps.
"It would have been really touch and go if it had been overseas, but the fact I had all those extra days leading into this one, I really just knew that I could be ready for it."
Walker has been to Vector Arena just once before this weekend - for a Rihanna and Chris Brown concert in 2008 - and she explained her delight at seeing the downtown venue covered in dirt.
"It's so cool to see that it's our sport in there and that people are coming to watch. To have age-group days sell out, I don't think that's happened at world champs before. I'm really looking forward to the weekend and seeing it packed out for the elites."
Though she was anticipating the atmosphere created by an indoor event - "it's going to be crazy" - Walker admitted she rarely noticed the crowd once the race was underway.
But for fans concerned by how Walker's healing arm may impair her ability, there was one, all-important, place where the crowd could make a difference.
"When you're on the start gate you can really hear the noise."
