There are some phenomenal riders taking part in the Pioneer.
Among the most notable in the gaggle of professional riders is the 13-time Spanish mountain bike champion. The elite riders rarely stop at aid stations and there have been sprint finishes on a couple of stages.
It's impressive stuff, but arguably more impressive is what happens at the other end of the course.
The Pioneer is tough, really tough. It challenges both mind and body as well as riding ability and the ones at the back of the field are often suffering, mostly quietly.
Only will-power keeps them going and even then it's often not enough.
About 10 riders failed to finish the 112km stage from Lake Ohau to Lake Hawea, which included an energy-sapping gain in elevation of 3578m.
By the time we got to the bottom of the final 1200m climb out of the Lindis to Grandview today, we had already travelled 85km and climbed more than 2000m.
Some riders didn't make the cut-off and were pulled out of the race, others withdrew (often unwillingly) but most struggled on. And it was a struggle.
One woman had barely eaten since breakfast by the time she got to the second aid station 74km into the journey. Food just wouldn't stay in her system.
But she kept moving, with the help of her supportive husband who pushed her bike for extended periods. Only 4km from the top of the final climb, her body wouldn't let her go on any further and she withdrew.
Later I caught up with her husband, who completed the stage, and he said the rocky descent down to Lake Hawea could have ended badly, given her condition. She was already on a drip.
It wasn't the only example of amazing willpower and team-work.
A Filipino rider, who had clearly never seen mountains like the Southern Alps, was also in a bad way. But he soldiered on and often his riding partner pushed both bikes before depositing them on the ground and then going back to push his friend up the hill.
"I just want him to get to the end," he said. "If we do, he owes me a big steak dinner."
He earned it.
It's this kind of show of will-power, strength and team-work which makes the Pioneer special. It makes no apologies for being challenging but it's also a big part of what draws people to the event.
Stubborness is a valuable commodity on a seven-day mountain bike race, but there is an amazing sense of achievement when another stage is ticked off.
That's five done, and only two to go.
The elite riders will power through the course tomorrow, a 64km ride up to the Snow Farm overlooking the Cardrona Valley. A lot of the rest of us will try to find whatever power we have left.