Given that the longest leg of any traditional triathlon distance is the bike, a challenging course can truly make or break your race. From relentless climbs to powerful headwinds, there are plenty of ways to zap your legs before you even get to the run. Veteran pros handpicked these seven courses as some of the hardest.

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Ironman Lake Placid

Outside of the world championship, Ironman Lake Placid is the longest-running full distance triathlon in North America. The quaint mountain town—which hosted the Winter Olympics in both 1932 and 1980—has been home to the event since 1999.

The two-loop, 112-mile course has a few distinct sections, including an 11-mile sustained climb and a three-part ascent nicknamed Baby Bear, Mama Bear, and Papa Bear, with a total of more than 6,000 feet of elevation gain. “It really tests all your bike skills—flat time-trialing, descending, and climbing,” said Sarah Piampiano—who took third in the event in 2018. “And if you do the first loop too hard you really pay for it on the second loop.”

Ironman/Ironman 70.3 St. George

When St. George debuted as an Ironman course in 2010, it instantly became known as one of the most demanding full-distance races of all time. It only ran for three years before it was cancelled due to low numbers and became a 70.3 race that served as home to the Ironman 70.3 North American Championship. The full course is back in 2022 and is sure to appeal to strong triathletes who aren’t scared to tackle the hilly red rock terrain.

“It is a fast course, but the combination of rolling hills, the Snow Canyon climb, the potential morning cold temperatures, and then the slight bit of altitude and dry air makes the course very challenging,” Piampiano said. “That race in general is one of the hardest out there.”

XTERRA Beaver Creek

If you’ve never raced off-road before, know that this Colorado XTERRA course will challenge even the most experienced mountain bikers. The 24.2-kilometer mountain bike course has a total elevation gain of 3,600 feet with plenty of punchy and extended trail climbs along Bachelor Gulch, Arrowhead, and Beaver Creek. “You start at 7200 feet, climb to 9500 feet, and then finish somewhere around 8000 feet after more quick descents and hard climbs,” Eric Lagerstrom said who recently took seventh at the race. “It’s absolutely brutal.”

Ironman Mont-Tremblant

The alpine village of Mont-Tremblant provides a magical setting for this full-distance race in Canada. The 112-mile course is described as “rolling” and doesn’t seem too intimidating, but as Meredith Kessler pointed out—it’s sneaky hard. “Mont-Tremblant is the epitome of ‘Beauty and the Beast’ with its gorgeous backdrop and tough terrain,” said Kessler—who won the 70.3 event three times in 2014, 2015, and 2018, as well as took third at the full-distance version in 2018. “It is filled with relentless rollers during the front end of the course with the last 12 miles being a series of short, sharp, and steep hills to get the legs properly tenderized before the run!”

Ironman Florida

“It’s pancake flat…” you might think. And yes, that’s true. This one-loop Panama City Beach course is known to be fast and void of any significant climbs. (The highest point on the course is literally 161 feet above sea level.) “But that’s what makes it hard,” said Skye Moench, who took second at the race in 2020 with the fastest bike split in the women’s pro field. “You are in aero the whole time, and there is no free-wheeling down a hill. Your body gets really sore and tired by the end of that! On top of that, there can be quite a bit of headwind at times, and that always makes things tough.”

Ironman 70.3 St. Croix

Although now discontinued as an Ironman event, this popular race in the U.S. Virgin Islands boasted a tough bike course that included “The Beast,” a grueling 15-percent-grade climb. “I always thought St Croix was a tough course, with lots of hills along with hot and humid conditions,” said Tim O’Donnell. (The race also holds a special place in O’Donnell’s heart—it’s where he and wife Mirinda Carfrae met in 2009.) Although you can no longer race the Ironman 70.3 course, you can still visit the island to tackle The Beast: The St. Croix Beauty and the Beast Triathlon offers a half- and sprint-distance course at the end of November.

Ironman World Championship

On paper, the Big Island bike course may look like a rolling, fairly manageable route with less than 6,000 feet of elevation gain over 112 miles. But the specific-to-Kona conditions are what make this bike so leg daunting. “The winds, humidity, and level of competition are what make this a really tough course,” said Linsey Corbin, who has placed in the top ten in Kona three times. Plus, when you’re racing the top athletes from around the globe, it’s easy to go a bit out of your comfort zone. “It has more to do with the competition and the heat, but the last 30 miles can be really hard if you get caught up in a pace above your abilities,” said Andy Potts who has finished in the top ten seven times throughout his career.