How to Take a Mountain Bike Down Bonette

The Col de la Bonette, located in the French Alps at an elevation of 2,802 meters (9,193 feet), is the highest paved road in Europe and one of the most legendary cycling climbs in the world. While its famously conquered by road cyclists ascending from Saint-tienne-de-Tine or Jausiers, few dare to descend it on a mountain bike. Taking a mountain bike down Bonette is not merely a technical rideits an epic adventure that demands preparation, skill, respect for terrain, and deep awareness of environmental and safety conditions. This guide provides a comprehensive, step-by-step roadmap for riders who wish to descend Bonette on a mountain bike, covering everything from route selection and bike setup to risk mitigation and real-world experience. Whether youre an experienced enduro rider or a seasoned trail enthusiast seeking a new challenge, this tutorial will equip you with the knowledge to navigate one of the most dramatic descents in alpine cycling.

Step-by-Step Guide

1. Understand the Route and Terrain

The descent of Col de la Bonette begins at its summit, near the Cime de la Bonette, and winds down approximately 24 kilometers (15 miles) to the village of Saint-tienne-de-Tine. The road is paved but features extreme gradientssome sections exceed 12%along with sharp switchbacks, loose gravel, crumbling edges, and minimal guardrails. The descent is not a single continuous slope; its a series of dramatic drops separated by short, steep climbs and technical corners. The first 8 kilometers are the most exposed, with sheer drops of over 300 meters on the right side and no barriers. The road surface varies from smooth asphalt to sections with cracked pavement, oil slicks, and fine gravel accumulation, especially near curves.

Before descending, study the route using detailed topographic maps or GPS platforms like Komoot, Ride with GPS, or Gaia GPS. Download offline maps and note key landmarks: the Bonette summit, the Col de la Bonette sign, the Courbes de la Bonette (the famous 21 hairpins), and the junction at Saint-tienne-de-Tine. Identify sections where the road narrows, where runoff is heavy, and where visibility is limited due to curves or fog.

2. Choose the Right Mountain Bike

While a full-suspension enduro bike is ideal, a hardtail with wide tires and strong brakes can also work if youre experienced. The ideal bike for Bonette should have:

• 150180mm of front and rear travel to absorb high-speed impacts and rough pavement sections
• 2.42.6 wide tires with aggressive tread for grip on loose gravel and wet asphalt
• Hydraulic disc brakes with at least 203mm rotors front and rear
• Low gear range for controlled climbing back up if needed
• Reliable wheelset with 3035mm internal width and tubeless-ready rims

Avoid lightweight race-oriented bikes. The descent is too punishing for minimal frames or narrow tires. Bikes with slack head angles (6465 degrees) and long reach improve stability at speed. Consider running a dropper post to lower your center of gravity during technical sections.

3. Prepare Your Bike for the Descent

Before hitting the road, perform a thorough pre-ride inspection:

• Brakes: Check pad wear. Replace if less than 1mm remains. Bleed the system to remove air. Ensure rotors are clean and free of oil.
• Tires: Set pressure between 1822 PSI depending on your weight and tire width. Use tubeless sealant and check for leaks. Consider adding a puncture-resistant liner if riding in remote areas.
• Drivetrain: Clean and lubricate the chain. Check for chain stretch. Ensure the cassette and chainrings are not worn beyond 0.75%.
• Wheels: Spin each wheel to check for true alignment. Tighten quick releases or thru-axles to manufacturer specs.
• Handlebars and stem: Confirm all bolts are torqued properly. Adjust bar width if needed for better control.
• Helmet and body armor: Wear a full-face helmet and consider elbow/knee pads. The consequences of a fall here are severe.

4. Plan Your Descent Timing

Timing is critical. The Bonette is open seasonally, typically from late June to mid-October, depending on snowmelt. Even in summer, early morning descents may encounter patches of ice or frost, especially on north-facing curves. Avoid descending after rainwet asphalt becomes dangerously slick, and runoff can wash gravel onto the road. The best window is mid-morning on a dry, clear day after the sun has warmed the pavement.

Check local weather forecasts and webcams from the Alpes-Maritimes prefecture. Wind is a major factorstrong crosswinds at the summit can destabilize riders. Avoid days with forecasted winds above 30 km/h. Also, be aware that the road may be closed to traffic on certain days for cycling events. Confirm accessibility with local tourism offices or the Mairie de Saint-tienne-de-Tine.

5. Acclimate to Altitude

At over 2,800 meters, oxygen levels are 30% lower than at sea level. Even fit riders can experience dizziness, nausea, or reduced reaction time. If arriving from low elevation, spend at least one night at 2,000 meters or higher before attempting the descent. Hydrate aggressivelydrink 500ml of water per hour leading up to the ride. Avoid alcohol and caffeine the night before. Carry electrolyte tablets and eat a high-carb meal 23 hours before descending.

6. Begin the Descent: Technique and Positioning

Start slowly. The first 500 meters from the summit are the most intimidating. The road drops sharply with no guardrails and a sheer drop to your right. Keep your weight centered over the bike, not too far back. Use a low gear to maintain momentum without spinning out.

Use the attack position: bend your elbows and knees, chest low, eyes looking aheadnot at your front wheel. Keep your pedals level (3 and 9 oclock) for balance. Avoid braking while turningbrake before the corner, then release and roll through. On tight switchbacks, shift your body weight inside the turn, keeping your outside pedal down and your inside knee slightly bent.

On long, straight descents, use controlled, intermittent braking. Apply both brakes evenly, but favor the rear slightly to avoid flipping over the handlebars. Avoid locking the front wheelthis is the leading cause of crashes on paved descents. Use engine braking (pedaling resistance) where possible to reduce brake fade.

7. Navigate the Hairpins

The 21 hairpin turns known as Les Courbes de la Bonette are the technical heart of the descent. Each curve is blind, steep, and often littered with gravel from erosion. Approach each turn at a speed you can comfortably stop within half the visible distance. Look for the apex of the turnride a wide arc to reduce lean angle and maintain traction.

On the left-hand turns (which are more frequent), be cautious of runoff from the mountain side. On right-hand turns, watch for loose gravel piled up by traffic. If you see debris, slow down and scan the surface before committing to the turn. Some riders choose to stand on the pedals during the tightest corners to improve balance and reaction time.

8. Handle Surface Changes

As you descend, the road surface transitions from smooth tarmac to cracked pavement, then to sections with exposed aggregate. Be especially alert near the 10-kilometer mark, where construction patches and older asphalt create uneven textures. Watch for reflective road markersthey often indicate oil spills or recent repairs. If you encounter a patch of wet oil, keep your bike upright, avoid braking, and coast through. Do not lean or turn abruptly.

When you hit loose gravel, lighten your grip on the handlebars. Let the bike move beneath you. Do not overcorrect. If you feel the rear tire sliding, gently ease off the brakes and allow the bike to straighten. Your tires are designed to griptrust them, but dont push beyond their limits.

9. Manage Brake Fade

Brake fade is the

1 cause of accidents on long descents. Hydraulic disc brakes can overheat after 1015 minutes of sustained braking. To prevent this:

• Use engine braking by downshifting and pedaling against resistance
• Alternate between front and rear brake application
• Take short breather sections where you coast and let the brakes cool
• Install larger rotors (203mm or 223mm) if possible
• Consider brake cooling fins or ceramic-coated pads for extreme heat resistance

If your brakes begin to feel spongy or lose power, stop immediately. Find a safe pull-off, turn off the bike, and allow 510 minutes for cooling. Do not continue if brake performance is compromised.

10. Final Kilometers and Arrival

The last 5 kilometers into Saint-tienne-de-Tine flatten slightly but become more urban. Watch for cars, cyclists, and pedestrians. The road narrows near the village entrance. Slow down, use your bell or voice to alert others, and be ready to stop at intersections. The final stretch is often the most dangerous due to complacencymany riders let their guard down after surviving the hairpins.

Once you reach the village, find a safe spot to stop, hydrate, and inspect your bike. Check for damage to rims, spokes, or suspension components. Even if the ride feels smooth, hidden damage can occur from high-speed vibrations. Document your descent with photos or GPS data for future reference.

Best Practices

1. Ride Alone? Not Recommended

While experienced riders may descend Bonette solo, it is strongly advised to ride with at least one other person. In case of mechanical failure, injury, or sudden weather change, having a partner can be life-saving. Carry a satellite communicator like a Garmin inReach or Zoleo for emergency signaling. Cell service is unreliable above 2,000 meters.

2. Pack the Essentials

Even though its a paved descent, youre in a remote alpine zone. Carry:

• 2 liters of water and electrolytes
• High-energy snacks (gels, nuts, bars)
• Lightweight rain jacket or wind shell
• Multi-tool with chain breaker and tire levers
• Mini pump or CO2 inflator
• First-aid kit with gauze, tape, and antiseptic
• Headlamp with extra batteries
• Identification and emergency contact card

Do not rely on shops or cafes along the route. There are none between the summit and Saint-tienne-de-Tine.

3. Respect the Environment

The Col de la Bonette is part of the Mercantour National Park, a protected alpine ecosystem. Do not litter. Avoid riding off-roadeven to bypass gravel patches. Stick to the paved road. Do not disturb wildlife. The area is home to ibex, marmots, and rare alpine flora. Your presence should leave no trace.

4. Know When to Turn Back

There is no shame in aborting the descent. If you feel fatigued, the weather turns, or your bike behaves unpredictably, stop. Find a safe turnout, assess the situation, and consider ascending back to the summit or waiting for conditions to improve. The mountain will still be there tomorrow. Your safety is not negotiable.

5. Train for the Descent

Before attempting Bonette, practice on similar terrain: long, steep, paved descents with switchbacks. Find local mountain passes with similar gradientssuch as the Col du Lautaret, Col dIzoard, or even the Stelvio Pass. Practice braking control, cornering technique, and endurance. Build up to 2+ hour descents with 1,500+ meters of elevation loss. Strength training for core and upper body will improve your stability.

6. Use a GoPro or Action Camera

Mount a camera to record your descent. It serves as both a memory and a learning tool. Review footage afterward to analyze your body position, braking points, and line choices. Many riders discover they were braking too late or looking down instead of ahead. Video analysis is one of the most effective training methods for technical descents.

7. Inform Someone of Your Plans

Before you start, tell a friend or local contact your intended route and estimated time of arrival. Provide your GPS track. If you dont check in within 2 hours of your estimated descent completion, they should alert local authorities. This simple step has saved lives on remote mountain passes.

Tools and Resources

1. GPS and Mapping Tools

• Komoot: Offers detailed elevation profiles and surface type indicators. Download the Col de la Bonette Descent route shared by top alpine riders.
• Ride with GPS: Allows you to overlay weather and traffic data. Use the Alpine Descent template for custom alerts.
• Gaia GPS: Excellent for offline topographic maps. Use the USGS 1:25,000 layer to identify elevation changes and terrain features.
• Google Earth Pro: Use the 3D terrain view to simulate the descent and identify blind corners.

2. Bike Maintenance Tools

• Park Tool BTS-2.2 Brake Bleed Kit for maintaining hydraulic brake performance
• Finish Line Ceramic Wet Lube reduces friction and resists dirt buildup
• RockShox Reverb Remote Dropper Post essential for lowering your center of gravity
• Lezyne Pressure Drive Pump accurate to 0.1 PSI for fine-tuning tire pressure
• Wolftooth Components Chain Catcher prevents chain drop on rough pavement

3. Protective Gear

• Bell Mips Full-Face Helmet certified for both MTB and road use
• Fox Racing Proframe Knee Pads lightweight, ventilated, and impact-resistant
• POC VPD Air Back Protector certified to EN 1621-2 for spine protection
• Giro Syntax Gloves grip-enhancing palms and reinforced knuckles

4. Weather and Road Condition Resources

• Mto-France Alpine Forecast official French meteorological service with 72-hour predictions
• Alpes-Maritimes Road Conditions Portal real-time updates on closures and maintenance
• Webcams from Col de la Bonette live feeds from the summit and key curves (search Bonette webcam)
• OpenStreetMap Mountain Bike Layer community-edited data on surface conditions

5. Training and Skill Development

• Mastering Mountain Bike Descents by Dan Kneen (YouTube) technique breakdowns for steep, technical terrain
• Alpine Riding Clinic by MTB Academy France in-person courses near Brianon
• The Art of Braking by Global Mountain Bike Network physics-based braking principles
• Enduro Racing Tactics by Trailside Skills applies race techniques to long descents

Real Examples

Example 1: Julien, 32, Professional Enduro Rider

Julien, a French enduro racer, descended Bonette in August 2022 after completing the Tour de France route on his bike. He used a Santa Cruz Hightower with 160mm travel, 2.5 Maxxis Minion DHF tires at 20 PSI, and 223mm rotors. He rode with a partner and carried a satellite beacon. He reported that the most challenging section was the 12th hairpin, where a recent landslide had left a 3-meter-wide patch of loose scree. He slowed to 12 km/h, stood on the pedals, and let the bike drift slightly to find grip. He completed the descent in 58 minutes with no brake fade. The key, he said, was not speedit was patience. Every corner demanded a decision. You cant rush the mountain.

Example 2: Maria, 45, Weekend Adventurer

Maria, a former road cyclist from Lyon, attempted Bonette on a 140mm trail hardtail with 2.3 tires. She underestimated the descents length and did not hydrate properly. At the 15-kilometer mark, she experienced lightheadedness and nearly lost control on a wet patch. She stopped, drank electrolytes, and waited 20 minutes before continuing. She finished in 1 hour 22 minutes, exhausted but proud. I thought I was prepared, she said. But altitude doesnt care about your fitness. You have to respect it. She now recommends a 2-day acclimatization plan for all riders.

Example 3: The Group of Four from Germany

A group of four riders descended Bonette in September 2023, each using different bikes: two full-suspension enduro rigs, one fatbike with 4.0 tires, and one gravel bike with mountain bike tires. The fatbike rider struggled with weight and inertia, taking 15 minutes longer than the others. The gravel bike rider, despite having no suspension, maintained control by using aggressive body positioning and feathering the brakes. The group documented their ride with a drone and created a 12-minute video that went viral in the European MTB community. Their takeaway: The right bike matters, but the right mindset matters more.

Example 4: The Incident at Hairpin 17

In July 2021, a rider descending Bonette on a carbon fiber race hardtail lost control at Hairpin 17 after applying the front brake too hard on a gravel-covered curve. He was thrown over the bars and landed on the roadside embankment. He suffered a broken collarbone and internal bleeding. Rescuers reached him after 45 minutes due to poor GPS signal. He later stated, I didnt wear a helmet. I thought I was too good to need one. His story is now used in French mountain biking safety seminars as a cautionary tale.

FAQs

Can I ride a road bike down Bonette?

Technically yes, but it is extremely dangerous. Road bikes lack suspension, wide tires, and powerful brakes needed to handle loose gravel, steep gradients, and high-speed vibrations. Most riders who attempt it on road bikes report severe discomfort, loss of control, and brake failure. A mountain bike is strongly recommended.

Is it legal to ride a mountain bike down Col de la Bonette?

Yes, as long as the road is open to traffic. There are no specific restrictions against mountain bikes. However, you must obey all traffic laws, including yielding to vehicles and not riding on closed sections. Always check local regulations before your ride.

How long does it take to descend Bonette on a mountain bike?

Experienced riders typically take 5070 minutes. Beginners or those riding conservatively may take 90120 minutes. The record for a mountain bike descent is 38 minutes, set by a professional downhill racer with a full DH rigbut this is not recommended for most riders.

Do I need a permit to descend Bonette?

No permit is required. The road is public and open to all vehicles and cyclists during the season. However, if you plan to camp or access the summit via hiking trails, you may need park entry authorization.

Whats the best time of year to descend Bonette?

July through September offers the most stable conditions. June and October are risky due to snowmelt or early frost. Avoid midday in Augustheat can soften asphalt and increase tire blowout risk.

Can I ride Bonette in the rain?

Never. Wet asphalt is extremely slippery, especially on steep, winding descents. Oil and rubber residue from vehicles create invisible slick zones. Rain also increases the risk of rockfalls and mudslides. Wait for dry conditions.

What should I do if my brakes fail?

Stay calm. Shift into the lowest gear and use engine braking. Look for a safe runoff areadirt shoulders, gravel piles, or grassy embankments. Avoid braking on pavement. If possible, steer toward a curve to reduce speed naturally. Signal for help if you have a communicator.

Is it safe to ride Bonette solo?

It is possible, but not advised. The risk of mechanical failure, injury, or sudden weather change is high. Always ride with a partner or inform someone of your plans. Carry a satellite device.

Are there any bike repair shops near the descent?

No. The nearest bike shop is in Saint-tienne-de-Tine, 24 kilometers down. Carry all necessary tools and spare parts. Do not rely on local services.

How do I get back up after descending?

You have three options: ride back up (a 2,800-meter climb), take a shuttle or taxi from Saint-tienne-de-Tine, or hitch a ride with a local service. Many riders arrange a pickup in advance. Do not attempt the ascent without proper gear and fitnessits one of the hardest climbs in Europe.

Conclusion

Descending Col de la Bonette on a mountain bike is not just a rideits a rite of passage. It tests your technical skill, mental resilience, physical preparation, and respect for nature. This guide has provided you with a detailed, step-by-step framework to approach the descent safely and confidently. From bike setup and route planning to braking technique and emergency protocols, every element has been designed to minimize risk and maximize reward.

Remember: the mountain does not reward speed. It rewards awareness. It does not honor bravadoit honors patience. The hairpins dont care how many medals youve won. They only care if youre present in the moment.

If you take away one lesson from this tutorial, let it be this: prepare like your life depends on itbecause it does. Ride with humility, respect the road, and honor the altitude. When you finally roll into Saint-tienne-de-Tine, the feeling wont be of triumphit will be of awe. You didnt conquer Bonette. You earned the right to pass through it.

Now go. Ride smart. Ride safe. And let the mountains remember younot for how fast you went, but for how wisely you rode.