Grand Colombier: France's Steepest Hidden Climb, a 22% Hellish Ramp Concealed Within 4.4 km of Relentless Ascent

The Tour de France Chose It Because Every Legendary Alpine Climb Had Already Been Conquered

Before 2012, if you mentioned the Grand Colombier to seasoned cycling fans, most would have looked puzzled. It’s not in the Alps, nor does it belong to the Pyrenees. Instead, it sits quietly on the southern edge of the Massif du Jura in eastern France, in a relatively obscure corner—the Bugey region of the Ain department. But in 2012, the Tour de France race director made a decision: to include this mountain in a stage, as a hors catégorie climb on the Culoz side.

Behind this decision lies a larger story. Before that, no climb in the Jura mountains had ever been classified as hors catégorie by the Tour—that ranking had always been the exclusive domain of the Alps and the Pyrenees. The Grand Colombier broke that convention, leaping to become “the only hors catégorie climb outside the Alps and the Pyrenees” at the time, until the Puy de Dôme rejoined the race route years later. This meant: the legendary climbs the Tour could choose from had already been ridden round after round, so it turned its attention to this long-overlooked mountain, which nonetheless possesses some of the steepest gradients in France.

If you ask any cyclist who has ridden the Grand Colombier, nine out of ten will tell you the same thing: this is not a “scenic, gently graded” tourist climb, but a brutal ascent that will make you question your life choices—especially the section known as the “Artemare direct route,” a 4.4-kilometer stretch with a continuous gradient above 12%, which hides a 400-meter segment averaging 18% and peaking at a hellish 22%. These numbers rank among the very steepest of all road climbs in France.

Route Basic Information

Different sources report slight variations in the exact summit elevation (1,498 m or 1,534 m) and route lengths, typically due to different starting points used by various organizations and GPS measurement errors. The figures above are approximate values compiled from multiple sources; please refer to on-site signage and GPS records for actual data.

Section-by-Section Breakdown: Four Roads, Four Personalities

The most distinctive feature of the Grand Colombier is that it doesn’t have just one “standard route,” but four ascent roads with vastly different characters. The Tour de France has even included three of these routes in a single edition, making riders experience the mountain’s different faces repeatedly within the same race.

Culoz Route (longest, relatively moderate but sustained gradient): This is the official route most frequently used by the Tour de France, approximately 18.3 km long with an average gradient of 6.9% and a maximum of about 14%. The early section departs from the small town of Culoz, climbing gently along roads through the forest with relatively even gradient changes—no sudden double-digit pitches like the Artemare route—but precisely because it’s longer, the sustained toll is equally significant. In the middle and later sections, continuous hairpin bends appear, and the view gradually shifts from forest to open alpine meadows, offering sweeping views down to the Rhône valley and the shimmering waters of Lac du Bourget below.

Anglefort Route (the steepest “normal” route): Approximately 15.2 km long with an average gradient of 7.9%, the highest average among the four routes, and a maximum of about 14%. This route’s defining characteristic is that there’s almost no respite—no gentle sections—maintaining a moderate-to-high intensity climbing rhythm from start to finish. It suits riders who prefer “grinding hard all the way” rather than alternating between steep and easy.

Artemare Direct Route (the infamous hell section): Approximately 15.9 km long with an average gradient of 7.8%, but what truly made this route notorious is a 4.4 km continuous steep section averaging over 12%, which itself hides a 400-meter extreme segment averaging 18% with a maximum of 22%. What does 22% mean? Converted to an angle, it’s a slope of just over 12 degrees. For the vast majority of amateur cyclists, merely keeping the front wheel from lifting and the rear wheel from slipping is already a considerable technical challenge, let alone sustaining power output to keep climbing. This section is also the main reason European cyclists call the Grand Colombier “one of the most painful climbs in France.”

Lochieu Route (shortest but equally tough): Approximately 13.1 km long with an average gradient of 6.8%, the shortest of the four routes, yet the maximum gradient still reaches around 15%. In the 2016 Tour de France, this route was combined with the Culoz route to create a “double ascent” stage design—riders first climbed to the summit from Lochieu, then descended via the Culoz side and climbed again. It was a true test of both endurance and mental fortitude.

Sensory Experience on the Mountain: Stark Contrast Between Forest, Lake Views, and the Hell Slope

Compared to the legendary, long-famous climbs of the Alps and the Pyrenees, the Bugey region surrounding the Grand Colombier retains a more rustic character. In the first few kilometers from Culoz, the road winds through dense deciduous forest; in summer, the canopy almost completely blocks the sunlight, forming a natural green tunnel. Combined with the mountain’s unique cool air currents, you can feel a hint of coolness even in the height of summer—a stark contrast to many bare, exposed high-mountain climbs.

As elevation increases, the forest gradually thins, and the view shifts from monotonous woodland to open landscapes. From the middle section of the Culoz route onward, you can clearly see the winding course of the Rhône valley below, as well as the glistening surface of Lac du Bourget in the distance—one of France’s largest natural lakes. On clear days, looking back from the mountainside, the interplay of lake and mountain scenery is often described by riders as “an unexpected surprise,” because most people had no idea this relatively obscure mountain would offer such expansive views.

But this tranquility stands in stark contrast to the Artemare direct route. When you turn onto that 4.4 km continuous steep section, the surrounding scenery seems to be muted in an instant—your attention is forced to focus entirely on the near-vertical tarmac ahead. The sound of your breathing, the chain rubbing, and the dull thumping of your heartbeat replace any mood for leisurely sightseeing. Many riders who have tackled this section describe the 400 meters at 18% average as “time standing still”—just a few hundred meters, yet it feels like an eternity. When you finally crest the steepest core section and return to gentler gradients, that overwhelming sense of relief is the Grand Colombier’s most direct reward to every challenger.

Gear Recommendations: Gearing and Brake Preparation for the Hell Slope

Facing a route like the Grand Colombier with its extreme gradients, equipment preparation differs significantly from a simple long-distance climb. The core concerns are two things: “is your gearing light enough” and “is your braking system reliable enough.”

Gearing Setup: If you plan to tackle the Artemare direct route, it’s strongly recommended to review your gearing setup before departure. Facing an instantaneous extreme gradient of 22%, even reasonably fit advanced riders may need a much lighter lowest gear than their usual training setup to maintain cadence, avoiding being forced to dismount and push—which is not only awkward on steep sections but also costs extra energy to restart climbing. In recent years, many cyclists opt for larger rear cassettes (e.g., 34 teeth or more) paired with compact cranksets to handle such extreme steep sections.

Wheels and Tire Pressure: The forest sections of the Bugey region occasionally have fallen leaves, gravel, and damp shaded areas. It’s advisable to choose road tires with good grip and adjust tire pressure appropriately to balance rolling efficiency and cornering stability, paying particular attention to grip on slippery, tree-shaded sections.

Braking System: As mentioned earlier, brake heat load on descents is a particular concern at the Grand Colombier. It’s recommended to check brake pad (or rim brake pad) wear before departure and consider carrying spare pads to avoid significant braking performance degradation after prolonged high-intensity use.

Power and Pacing Estimates: How the Physics Model Calculates

Using the most common Culoz route (18.3 km long, 6.9% average gradient, approximately 1,263 meters of climbing) as the basis, applying a standard physics model:

P = (Fg + Fr + Fa) × v ÷ drivetrain efficiency

Fg = m × g × sin(arctan(gradient))       gravitational component
Fr = m × g × cos(arctan(gradient)) × Crr   rolling resistance
Fa = 0.5 × ρ × CdA × v²               aerodynamic drag

Using the following assumed parameters:

• Total mass m = 70 kg rider + 9 kg bike and gear = 79 kg
• Gravitational acceleration g = 9.81 m/s²
• Rolling resistance coefficient Crr ≈ 0.005 (road tires on asphalt)
• Drag area CdA ≈ 0.32 m² (seated climbing position)
• Air density ρ: slightly reduced with elevation (route ranges approx. 240–1,500 m)
• Drivetrain efficiency ≈ 0.975

Using Python to iteratively solve this model for different power-to-weight ratios corresponding to average speed and time, results are as follows:

The above are overall average estimates for the Culoz route, not accounting for real-world variables such as wind, road surface, or rider size differences. However, it must be emphasized: this “6.9% average gradient” figure masks the true destructive power of the Grand Colombier’s various routes—if converted to that 400-meter section on the Artemare direct route averaging 18%, the instantaneous speed at the same power-to-weight ratio would be far lower than the overall average. The physical pain riders actually experience on that section is far more intense than “just over 7% average” sounds. The physics model confirms this: at an 18% gradient, the power required just to overcome the gravitational component skyrockets, and even at professional-level power output, instantaneous speed can be reduced to near walking pace.

Regarding Professional Records: Since its Tour de France debut in 2012, the Grand Colombier has been a race focal point multiple times in 2016, 2017, 2020, and 2023. The 2020 edition even arranged for riders to cross three of the four routes in a single stage. Because the route combinations, race tactics, and peloton dynamics vary enormously between editions, professional riders’ actual climbing times are not suitable for direct comparison, so precise data is not cited here.

A Taiwanese Cyclist’s Perspective: Translating to Your Abilities

If you’ve ridden the steep ascent of Wuling (Provincial Highway 14甲) from Cingjing Farm to Hehuanshan, or you’re familiar with the continuous switchbacks of the Beiyi Highway’s “Nine Bends and Eighteen Turns,” the Artemare route at the Grand Colombier might hit you even harder—Taiwanese roads rarely feature continuous 400-meter-plus sections averaging 18%. This intensity is closer to certain single, brutally steep climbs (like the “hell slopes” on some rural access roads), except the Grand Colombier places it in the middle of a nearly 16 km long climb, testing your ability to “face a hell slope when you’re already exhausted.”

If you’re planning to challenge this mountain, here are some practical reminders (general guidelines only; for actual planning, please refer to the latest official announcements and local information):

• Route Selection: For a first attempt, it’s recommended to start with the more evenly graded Culoz or Lochieu routes, saving the Artemare direct route for when you’re fully prepared and confident in your steep-climbing technique.
• Season: The Bugey region’s climate is milder than the high Alps, with a relatively longer season for riding, but winter snowfall can still affect road conditions. Check recent weather and road information before departure.
• Gearing Preparation: Facing the extreme 22% section, your gear ratio will directly determine whether you can maintain an effective pedaling cadence. It’s strongly recommended to prepare a lighter maximum gear than for typical long climbs, to avoid being forced to dismount and push due to insufficient gearing.
• Transportation: Most cyclists use Lyon or Geneva as their base for travel to and from the area. For actual car rental and transfer arrangements, please consult official local channels; specific prices and schedules are not listed here.

Section Pacing Strategy: Save Energy Before the Hell Slope

Facing a route design like the Grand Colombier—“hiding an instantaneous hell slope”—pacing strategy must be more refined than for a simple long climb. Taking the Artemare direct route as an example, do not use excessively high power output on the relatively gentle early sections, because the real test lies ahead—that 4.4 km continuous steep section, especially the core 400-meter extreme segment, requires you to preserve a significant reserve of anaerobic and muscular capacity.

A more prudent approach is to keep the early sections at around 70% to 75% of your functional threshold power (FTP), deliberately holding back so your heart rate and breathing still have margin. Before entering the continuous steep section, take a brief mental and physical reset if needed (a sip of water, deep breaths, confirm the gear is already shifted to the lightest), then allow yourself to briefly push up to near or above FTP on the steep section—this terrain is not meant for “steady cruising,” and short anaerobic efforts are reasonable and necessary. After passing the steepest core section, the remaining gentler gradients allow you to return to a steady rhythm and gradually recover.

If you choose a route with more even gradient distribution like Culoz or Lochieu, the pacing logic reverts to the standard progressive strategy for long climbs: conservative early, steady middle, and within your limits late, avoiding burning out in the final kilometers before the summit from overexcitement.

Safety Reminders: The Braking Hell of Steep Descents

The most easily overlooked risk at the Grand Colombier isn’t actually the ascent—it’s the descent. Especially when descending from the 22% extreme steep section on the Artemare route, your braking system will endure heat loads far exceeding those of typical climbing routes.

Brake Overheating on Descents: On continuous extremely steep descents, if you brake constantly rather than intermittently releasing, disc rotors or rim brake pads can easily overheat, causing reduced braking power or even failure (thermal fade). It’s recommended to use “pulse braking”: brake firmly for a short period to slow down, then release to allow heat to dissipate, repeating as needed, rather than holding the brake levers continuously.

Blind Corners: Multiple routes feature dense hairpin bends, some with poor visibility, plus occasional agricultural vehicles or local residents’ cars in the mountains. Stay alert on descents and avoid excessive speed into blind corners.

Weather Changes: Although the Jura mountains aren’t as high as the Alps, they still have mountain-type weather, with afternoon thunderstorms common. Wet roads combined with steep descents significantly increase risk. It’s advisable to avoid starting during the typical afternoon thunderstorm window.

Cardiovascular Strain from High-Intensity Steep Sections: Producing maximum power output on gradients above 20% in a short time places considerable instantaneous strain on the cardiovascular system. If you have a history of cardiovascular conditions or have been feeling unwell recently, carefully evaluate whether to challenge the Artemare route. If you experience chest tightness, abnormal palpitations, or severe dizziness, stop immediately and seek medical attention. The advice in this article cannot replace professional medical evaluation.

One Mountain, Four Roads: The Philosophy of Stage Design

A major challenge facing Tour de France race directors in recent years is how to find stage material with sufficient difficulty and fresh appeal beyond the traditional mountains that have been used repeatedly for decades. The Grand Colombier happens to answer this need—it has four distinctly different ascent routes, meaning race designers can rearrange combinations year after year, giving riders “the same mountain, different ways to suffer” each time, avoiding aesthetic fatigue for both spectators and riders.

The 2016 stage design was particularly ingenious: riders first climbed to the summit via the Lochieu route, then instead of simply descending away, they detoured through the Culoz side and climbed again—effectively arranging a “double summit” ultimate test within a single stage. This design posed a severe challenge to professional teams’ energy allocation strategies and quickly built the Grand Colombier’s reputation among hardcore mountain enthusiasts within just a few years. By 2020, the race went even further, having riders cross three of the four routes in one go—a veritable “carpet bombing” tribute to the mountain. In 2023, the Grand Colombier was again featured as a key stage, continuing to cement its indispensable place in the modern Tour de France landscape.

This “one mountain, many roads” design philosophy has also made the Grand Colombier one of the representatives of what European cycling circles now call “the new generation of must-pilgrimage climbs”—it proves that legendary climbs need not only be born in the Alps or the Pyrenees. As long as the gradients are hard enough and the routes have enough variety, even a relatively obscure mountain range like the Jura can nurture classic stages worthy of the Tour de France’s history.

The Appeal of a Hidden Climb: Why It’s Worth the Detour

Perhaps the most captivating thing about the Grand Colombier is precisely the fact that it’s “not that famous.” Compared to the perpetually crowded Alpe d’Huez in the Alps, or the Tourmalet in the Pyrenees that has long become a tourist landmark, the Grand Colombier only truly stepped onto the international stage in 2012, and it remains a relatively unfamiliar name on many Taiwanese cyclists’ bucket lists. But precisely because of this, it retains a purer climbing atmosphere—no shoulder-to-shoulder pilgrimage pelotons, no souvenir shops scattered across the mountainside, just quiet forest roads, expansive views of the Rhône valley, and that 22% hell slope you’ll never forget.

For advanced cyclists who have already conquered famous climbs like Wuling or Alpe d’Huez and are looking for “the next challenge,” the Grand Colombier offers a distinctly different kind of suffering—not the endurance drain of long distances, but a test of strength against near-limit gradients in a short time. The four routes with vastly different characters also allow you to plan a deep cycling trip of “one mountain, four ways to ride,” even challenging yourself to conquer two or more routes in a single day, personally experiencing the agony Tour de France riders endured in that 2020 “three routes in one stage” ordeal.

If you’re planning a cycling trip in eastern France, the Grand Colombier pairs beautifully with other nearby Jura or outer-Alps routes to form a multi-day itinerary, covering forest, lake, and hardcore climbing—three completely different riding experiences in one journey. Compared to classic Alpine routes that require months of advance planning and are hard to book in peak season, the Grand Colombier remains relatively niche, which also means more flexible scheduling and a quieter riding experience.

Key Takeaways

• The Grand Colombier has four ascent routes with vastly different characters: Culoz (longest, most even), Anglefort (steepest “normal” route), Artemare (hiding the 22% hell slope), and Lochieu (shortest but equally tough)
• Became the first hors catégorie climb in the Jura mountains at the 2012 Tour de France, subsequently selected for stages in 2016, 2017, 2020, and 2023
• Based on physics model estimates, the Culoz route takes a general enthusiast (2.5 W/kg) approximately 1 hr 34 min, a competitive rider (4 W/kg) about 61 minutes, and professional level about 50 minutes
• The core 400-meter section on the Artemare route at 18% average (22% max) requires special energy conservation and gear ratio adjustments
• On descents, use pulse braking to avoid thermal fade; afternoon mountain thunderstorms and slippery steep roads are the main safety risks

Related Reading

• 19 km, 1,522 meters of climbing: Col du Galibier, the Tour de France’s “heartbreak and beauty combined” Alpine giant
• Alpe d’Huez, France: A cycling pilgrimage guide to the Tour’s legendary 21 switchbacks
• Conquering the French Alps: A pilgrimage through the Tour de France’s classic mountain routes
• From Lake Geneva to the Mediterranean: The complete 12-day guide to France’s Route des Grandes Alpes