The Susitna 100, which starts Saturday at Big Lake, bills itself as "a winter race in frozen Alaska."

The race, which takes place over two days, is 100 miles long. Racers can ski, bike or run, but the overwhelming majority bike. The website promises "you will enjoy the challenge of winter racing in Alaska on marked trails with spectacular views and varied conditions."

It seems this is either an invitation or a veiled threat.

No doubt, the Susitna 100 is an enormous feat and, perhaps, a mysterious event to those of us who haven't attempted it. I spoke to a few contestants to get a sense of what it's like to prepare and participate.

Christina Grande, fat-tire cyclist extraordinaire and friendly face at The Bicycle Shop in Anchorage, entered her third Susitna 100 this year.

Grande said she first gave the race a go in 2015 after a series of shorter winter bike races.

"They seemed impossible at first and then you start to do them and it's pretty fun," she said. "Susitna was my very first century (100-miler) ever, including road bike. I figured, it's a slower pace, so maybe I'll just try."

Grande's first race was challenging, and because of slow conditions she needed 19 hours to finish.

"The biggest thing I encountered was tunnel vision at one point, because you're looking at similar things for so long there's really nothing different, especially the river part," she said. "I pulled over to my friend Amy — we were riding together — and I said, 'Amy, I think we just need to stop and have a conversation' to reset our minds a little. After that, we felt great.

"To this day, if we're too tired we're like, 'We need to have a conversation.' "

Another third-time racer, Laura Fox, won the women's race in 2015.

"It was soft, crystally, sugary snow that was really hard to ride in," Fox said. "There were sections where you had to push your bike, which made the race take longer. People were struggling by themselves through soft areas.

"I was surprised when I was first. All of us were pretty wiped by the end."

Both riders said the race's volunteers, checkpoint hosts and other contestants help keep them motivated to participate.

Last year, with hard-pack snow and low temperatures, the race was much faster. Grande finished in 11 hours, shaving a full eight hours shaved off her previous time. Fox, who was the second-place woman, finished in 8 hours, 44 minutes.

Grande laughed when asked about her favorite part of the race.

"Ten miles to the finish," she said. "I also like riding through the trees on the dog sled trails. It's fun and swoopy, mentally more stimulating."

This year, neither woman is sure what to expect. It could be fast, it could be slow.

"I'm looking at the weather a ton," Grande said. "But you know, it is what it is."

Fox said she's grateful musher Martin Buser's Happy Trails Kennel is hosting the start and finish, especially since conditions can vary so wildly. Racers can lie down and sleep if necessary before heading home. Two years ago, Fox needed the break.

"Even as I was lying there trying to take a nap, I was having visions of the trail right in front of me after riding for so long," she said. "I couldn't sleep because I just (kept) on riding in my head."

Susitna 100 veteran Al Mitchell, also known as "Super Al," said he's as ready as he'll ever be.

On how he got his nickname, Mitchell said, "A really long time ago I started entering these silly races and I thought a moniker would be appropriate because I'm not a Super Al."

His first Susitna 100 was in 1997, when the race was called the Iditasport. Kim Kittredge, a friend who is now the Susitna 100 race director, thought it sounded fun and convinced Mitchell to give it a try.

"In '97 the first race was on foot," Mitchell recalled. "A hundred miles is a long way and that really hurts. Then in '98 I did it on skis, and you have to be in really good shape to do it on skis, and that one hurt. So we decided bicycles — anybody can bike 100 miles. That just seems reasonable to a normal person."

With a few exceptions, he's participated in the Susitna 100 on a bike ever since.

"You think, 'I'm out there, I'm not really having any fun.' But the people who do these races are pretty upbeat people, their cup is not half empty, it's half full. It's fun to hang out with these people," Mitchell said.

How does he think this year's race will go?

"I think it's going to be pretty awful."

Between abundant snow and the recent warm weather, conditions could deliver a difficult race. Yet more than 100 racers will show up at Big Lake on Saturday prepared to race 100 miles over whatever conditions they find. And you can bet you'll see most of them back in 2018.

Alli Harvey lives, works and plays in Southcentral Alaska.