The 10 Most Challenging Downhill Mountain Bike Trails

Most trails accessible to everyone are subjectively difficult, but there are trails that defy convention and push the limits of even the best mountain bikers. Mountain Bike Trails are rated with a unified system that breaks the difficulty down into five succinct categories depending on six parameters: surface features, gradient (level of steepness), trail width, natural obstacles, technical features, and fitness level required.

Trail classifications start at “white circle,” which is the easiest rating, and end at “double-black diamond,” which is the most difficult rating bestowed on a trail, but it does go beyond that, and “pro line” trails are a step above what the average person would be able to ride.

While pro-line trails are typically rated as double-black diamonds, they receive an extra designation notifying riders of the skill level required and the assumed risk of dropping in on one of these courses. A pro-line trail will feature mandatory jumps and gaps, Large features, Steep downhill challenges, No ride-arounds, and severe natural or constructed elements, and they should only be ridden by highly experienced riders.

This is a list of what we deem the most challenging trails in the world, and they vary from black-diamond to pro-line. Read on to find the most challenging downhill mountain bike trails in the world. Will you check these off your bucket list?

1. Porcupine Rim, Moab, UT, USA

Difficulty: Black-Diamond
Length: 14.7 Miles

The iconic Porcupine Rim ride is an essential experience for any mountain biking enthusiast and a classic in Moab. This exhilarating route brings you to the breathtaking edge of Castle Valley before launching you into a thrilling, bone-jarring descent toward Jackass Canyon. From there, you’ll navigate beautiful singletrack trails that wind down to the banks of the Colorado River.

Need to know
This ride offers an authentic backcountry experience, but be cautious—attempting shortcuts through open terrain can lead to unexpected challenges and dire consequences. Bring plenty of water and food, and be ready for a longer adventure than you might anticipate.

• Slickrock Slabs
• Exposure
• Technical climbing sections

2. Hangover, Sedona, AZ, USA

Difficulty: Double-Black Diamond
Length: 3.2 Miles

This trail offers one of the most unique biking experiences in Sedona. It ascends to a saddle between two towering red rock formations, then follows a narrow ridge that lifts riders 200 feet above the canyon floor.

Need to know
It's important to note that, despite its short length, this trail is quite challenging. Riders should have a high level of confidence in their skills and fitness, as well as a comfort with heights!

The trail is primarily on slickrock, which presents a significant challenge, featuring step-ups, roll-offs, and off-camber sections. The first climb to the saddle is relatively safe and fully rideable for advanced riders, though it will make you pause in several spots. Once at the expansive flat saddle, take a moment to relax, refuel, compose yourself, and plan your next move. If you prefer to enjoy the stunning views without the exposure that follows, this is a great spot to turn around and retrace your steps.

• Exposure, exposure, exposure!

3. Blackjack, Pine, CO, USA

Difficulty: Double-Black Diamond
Length: 1.7 Miles

This downhill is highly technical, presenting a challenge that will humble even the most skilled riders. The trail lacks a smooth flow, with numerous features on Blackjack designed to test your abilities. While most obstacles have alternate lines, they are not easier lines. However, all features are manageable.

Need to know
This trail is not suitable for intermediate or beginner riders. It is full of steep, technical sections and lacks flow when you aren't pointing straight downhill.

• Technical chutes
• Granite slabs
• Hard to follow trail

4. The White Line Trail, Arizona, USA

Difficulty: Pro-line
Length: 1,322 ft

This trail starts as a steep push to the line, but once you’re at the top, hop on and ride the white line to the edge. Point your bike down the slope and focus on not making any mistakes. After completing the turn, return along the lower ledge.

Need to know
Be aware: This is a high-profile line, and spectators will be watching. Keep in mind that a fall could be catastrophic. The ride out offers a bit more room for recovery if you slip, but a tumble on the return leg could be life-threatening.

If you have strong bike handling skills and are comfortable on off-camber rock with quality tires, the line itself isn’t technically challenging. However, the potential for serious injury is obvious.

• Deadly fall
• Exposure
• Lots of onlookers

5. King Kong in Virgin, Utah, USA

Difficulty: Pro-line
Length: N/A

Virgin has emerged as a popular destination for those seeking desert riding adventures. With rideable conditions throughout most of the winter, it provides an excellent opportunity to emulate the pros at Redbull Rampage. On King Kong, riders will encounter numerous mandatory gaps and steep chutes on this trail, and failure to master them could result in a catastrophic tumble down the hillside.

Need to know
King Kong is notoriously challenging and isn’t officially sanctioned, as it is a section that has dire outcomes if the average rider attempts it. However, determined riders can still track it down with some research and access it via another trail with a similar theme.

• Steep chutes
• Exposure
• Mandatory features

6. Portal, Moab, UT, USA

Difficulty: Double-Black Diamond
Length: 2.5 Miles

This trail descends 1,000 feet over just a mile, with significant exposure alongside a 1,300-foot cliff. There have been serious accidents here, so it's essential to approach this ride with caution. While it's incredibly unique and scenic, only expert riders should attempt it, and intermediates with a positive attitude should be prepared to walk much of the trail.

Need to know
The Portal Trail initially offers a gentle downhill grade and smooth terrain. However, that comfort doesn't last long. You'll soon encounter a "Dismount Here" sign from the BLM—and they mean it. Unless you’re very familiar with this section, highly skilled, and willing to accept the risks, it's best to dismount. The moves aren’t technically impossible, but the consequences of a mistake can be severe, with several boulders poised to push you right off the trail and over the cliff.

• Technical chutes
• Rock slabs
• Exposure

7. Dirt Merchant, Whistler, British Columbia, Canada

Difficulty: Double-Black Diamond
Length: 0.6 Miles

If you're after a thrilling ride filled with airtime, Dirt Merchant is the trail for you. Starting from the qualifying drop-off of EZ Does It, this expert-only, machine-built trail offers a high-speed course featuring table tops, step-ups, and plenty of drops.

Need to know
There's a lot to enjoy, but be prepared to commit, as many steep takeoffs can feel quite blind! At the bottom, you'll encounter three options for crossing the creek: the left is a ride-around, the center is a moderate gap, and the right is a larger gap that requires plenty of speed.

• Jumps
• Drops
• High-Speed

8. Yungas Road, Bolivia

Difficulty: “The Death Road”
Length: 38.7 Miles

While this is not technically a “trail,” if you were to search the most dangerous bike rides in the world, this would likely make the list, and with its seldomly maintained surface and perilous exposure, we had to put it on the list.

Need to know
This route links La Paz to the Yungas region, featuring a winding, snake-like road carved into the Andes mountains, where riders will face a long descent at high altitude, with some sections measuring only 3 meters wide.

• Tours available
• Exposure
• Steep cliff faces
• Traffic

9. Dead Dog, Golden, British Columbia, Canada

Difficulty: Double-Black Diamond
Length: 1,020 ft

This trail is not for the faint of heart or inexperienced riders. It begins with a shale entrance that requires careful navigation, as gaining unwanted speed is easy. This loose section provides an opportunity for some great controlled brake-carving.

Need to know
While the rest of the trail isn’t shale, it does get steeper once you enter the trees. It's advisable to give each rider ample space before descending, as restarting from a complete stop on the slope can be very challenging. Be cautious—loose rocks can easily get dislodged and roll down towards riders below.

The trail is not regularly maintained, so expect deep ruts from erosion, exposed roots, and rocky sections due to its aggressive pitch. There are a few catch berms to help slow you down, but be prepared to rely on your brakes throughout the ride.

• Deep ruts
• Roots
• Aggressively steep

Related: Top 10 Mountain Bike Trails in the USA

10. Hardline, Dinas Mawddwy, Machynlleth, Wales

Difficulty: Pro-line
Length: 1.4 Miles

The Hardline track in Wales boasts a vertical descent of 1886 feet over 1.4 miles. For the 2024 course, a new section called "On-Off" was introduced, featuring a 40-foot gap, a 30-foot landing pad, and another 40-foot gap. This section is regarded as technical, demanding precision and skill from riders, and is not open to the public for good reason.

• Pro line in every sense of the word, as it is only open to pro riders

Honorable Mention: 19th Hole, Squamish, BC, Canada

Difficulty: Double-black Diamond
Length: 3,493 Feet

This trail, like many other double-black trails in Squamish, is relentlessly steep and requires incredible commitment and skill to navigate without incident..

Need to know
The 19th Hole is a segment of Squamish’s original downhill mountain bike shuttle lap, created nearly 30 years ago by Dave Kelly. It is designed to be steep and challenging and is still one of the most popular trails in the area despite its incredibly technical features and steep slabs and chutes.

• Steep Chutes
• Rock Rolls
• Drops and Jumps

Happy Trails!

While this is a relatively short list in the grand scheme of things, these are some shining examples of how challenging trails can be and how far experienced riders can push the sport. For more information on trails near you, we suggest utilizing local knowledge from bike shops or other resources.

Have fun, stay safe, and make smart choices!