10.1 km, 11.9% average, 22% max: Why riders call Italy's Monte Zoncolan "the Caesar"

Ten kilometers—doesn’t sound long, right? Plenty of people ride more than that just warming up. But if within those ten kilometers, over six of them hover around a 20% gradient, you’ll find that the word “short” completely loses its meaning here. This is Monte Zoncolan—a mountain in the Friuli region of northeastern Italy with a reputation so loud it has earned its own nickname: riders call it “Kaiser,” meaning “Emperor.” There are only a handful of climbs in the world worthy of such a title.

A Mountain That Was Once Only for Shepherds

Before Zoncolan became a cycling shrine, it was for a long time just a working road used by residents of the Friuli mountains to travel between the Gorto valley and surrounding settlements. The road was primitive, and the gradient so steep that even the locals saw no point in paving it properly. It truly stepped onto the international stage in 2003, when the Giro d’Italia included it in the route for the first time—the organizers chose this road, in a sense, deliberately to create a “test from hell.”

Since its debut, Zoncolan has almost become a fixed card in the Giro’s scheduling of decisive mountain stages, appearing time and again as the “deciding point.” It has witnessed summit victories by riders including Gilberto Simoni, Ivan Basso, and Igor Antón, and has also appeared in the Giro Donne. In recent Giro coverage, Zoncolan continues to be listed by cycling media as one of the race’s most brutal climbs, and the nickname “Kaiser” has been seared into fans’ minds through repeated broadcast images.

Interestingly, the road was only fully paved in recent decades—before that, the final few kilometers were actually just a gravel working road. In other words, Zoncolan’s “legendary” history is actually relatively young. It doesn’t have a two-hundred-year military road story like the Stelvio, yet in just over twenty years, purely through its gradient numbers, it has forced its way into the ranks of the world’s most famous climbs.

This also explains why Zoncolan’s “legendary feel” differs from climbs like the Stelvio or those in the Dolomites—it has no ornate roadside architecture, no century-old hotels, no baggage of aristocratic summer retreats. It relies purely on being “unreasonably hard” to build a near-mythical status in a short time. When cycling media covers the Giro, they frequently compare it directly with other famous ultra-steep climbs in Europe, and the conclusion of every comparison almost always points in the same direction: when it comes to the “sustained cruelty of the gradient,” Zoncolan struggles to find a true rival.

Why Zoncolan’s “Difficulty” Is Different from Other Climbs

If you’ve already read the other installments in this series covering the Stelvio or Mortirolo, you might think: “Aren’t they all just steep climbs? What’s the essential difference?” The difference is actually crucial.

The Stelvio’s difficulty comes from the combined effect of “length + altitude”—you have to hold on for over two hours while facing the oxygen-uptake pressure of thin air. The Mortirolo’s difficulty comes from “repeated short-wall impacts”—steep sections alternate with relatively gentler ones, forcing your body to constantly switch between aerobic and anaerobic effort. Zoncolan’s difficulty is the simplest and most direct: it is simply steep, relentlessly, with no rhythm to speak of. From the moment you enter the core hell section, your body stays locked in the same extreme intensity zone, uninterrupted for five to six kilometers.

This load pattern of “single intensity, sustained over a long duration” challenges the muscles more than the cardiovascular system—you’re not fighting to breathe; you’re fighting the sustained contraction capacity of your quadriceps and glutes. Many riders who have done all three routes recall afterward that Zoncolan actually feels “less breathless,” but it’s the one where “the legs give out first.”

Route Basic Information

Zoncolan has three main ascent routes, of which the one starting from Ovaro is the most frequently used by the Giro and is the true source of the “Kaiser” title. Please note: different databases often differ in starting points and measurement methods; all figures below are approximate, and actual roadside signage takes precedence.

Item	Details
Country / Mountain Range	Italy, Friuli-Venezia Giulia region, Carnic Alps
Start → Finish (Ovaro side)	Ovaro → Monte Zoncolan summit
Length	Approx. 10.1 km
Total Elevation Gain	Approx. 1,210 m
Average Gradient	Approx. 11.9%
Maximum Gradient	Approx. 22%
Start / Finish Elevation	Approx. 560 m → Approx. 1,730 m
Source of Fame	Multiple Giro decisive stages, riders’ nickname “Kaiser,” widely recognized as one of Europe’s steepest paved climbs

Comparison of the three ascent routes:

Route	Length	Elevation Gain	Average Gradient	Characteristics
Ovaro side	Approx. 10.1 km	Approx. 1,210 m	Approx. 11.9%	The official Giro route, with continuous extreme steepness in the middle-to-late section; source of the “Kaiser” nickname
Ovaro side “true climb” (measured from Liariis)	Approx. 8.5 km	Approx. 1,150 m	Clearly higher than the full-section average, with parts approaching 20%	The core hell section recognized by riders; the gentler village roads at the start are not counted
Sutrio side	Somewhat longer, estimated around 13 km	Around the 1,200 m range	Around the 9% range, relatively “milder”	Longer distance but more evenly distributed gradient; still a hard climb
Priola side	Less data available; length and gradient fall between the other two	—	—	Less frequently used; road condition info should be confirmed on-site or via the latest route platforms

All three routes eventually converge near the summit. Most riders and media agree that the Ovaro side is the “authentic” Zoncolan—because it’s the side the Giro uses most often and has the most extreme gradient.

The Ovaro Side: A Four-Section Breakdown

Zoncolan’s special characteristic is that its “difficulty” is highly concentrated in the second half, while the first half is relatively forgiving—this contrast between front and back is exactly what makes it so insidious.

Section 1: Pretending to Be Normal (Start to the village of Liariis, approx. 1.5 to 2 km)

Departing from Ovaro, the gradient in this initial stretch is relatively mild, the road width is still comfortable, and you pass a few small settlements. Many first-time riders will think here, “The legendary Kaiser is nothing special”—and that’s exactly where the danger begins.

Pacing focus: Don’t be fooled by how easy this section feels. Keep your heart rate and power at 85% to 90% of your target, and preserve your body’s—especially your muscles’—glycogen stores intact for the hell that follows.

Section 2: The Gates of Hell Open (After Liariis to approx. 5 km)

Past Liariis, the road surface almost immediately turns hostile. From here, the gradient stays consistently above 15%, with some sections reported at or even reaching 20%. This is where the “real Zoncolan” recognized by riders worldwide begins—the gentler section before is often even ignored in timing and records, because what truly decides life and death starts here.

The road in this section climbs almost straight up, without many hairpin turns to ease the gradient curvature (unlike the switchback terrain of the Stelvio or Mortirolo). This means you get no “breathing room at the apex”—the gradient is continuous and direct.

Pacing focus: This is a pure test of muscular strength and mental tolerance. Be sure to use your easiest gear and keep your cadence at the lowest sustainable level you can control. Don’t try to “power through” with speed—on a near-20% gradient, most people’s maximum speed is only a few kilometers per hour anyway. You won’t go much faster, but you’ll burn through your energy far more quickly.

Section 3: Tunnels and Cliff Walls (approx. 5 to 8 km)

This section passes through several short man-made tunnels or rock-wall corridors—a very distinctive topographical feature of Zoncolan, where the road is carved directly into the mountainside. Inside the tunnels, lighting is dim, the road surface may be damp, and with the gradient still holding at high double digits, this is the most mentally demanding stretch of the entire climb.

Pacing focus: Slow down before entering a tunnel to let your eyes adjust to the change in light. Visibility is limited inside, so maintain a steady pedaling rhythm and avoid suddenly changing your pedaling force because you can’t see the road clearly—that can easily cause the rear wheel to slip or you to lose balance.

Section 4: The Final Gravel Memory (Approx. 8 km to the Summit)

Near the summit, the gradient eases slightly and the views open up, revealing the ridgelines of the surrounding Carnic Alps. A few decades ago, this stretch was still a gravel access road; today it is fully paved, but the raw, primal feel of the terrain remains—there are few commercial facilities, and the summit typically has only simple signage and minimal visitor amenities.

The psychological impact upon reaching the top is peculiar: because the preceding near-20% hell has already drained most of your emotions, arriving at the summit often feels like a “numb relief” rather than the jubilant celebration you’d experience on the Stelvio.

Power and Pacing Estimates: Translating the “Kaiser” into Numbers

The following calculations use a standard physical model, as outlined below:

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                    Air Resistance

Assumed Parameters:

• Rider weight 70 kg + bike and gear 9 kg = Total weight 79 kg
• Gravitational acceleration g = 9.81 m/s²
• Rolling resistance coefficient Crr ≈ 0.005
• Drag area CdA ≈ 0.32 m² (climbing position; at Zoncolan’s extremely low speeds, air resistance has a negligible impact on overall power demand, with the gravitational component dominating almost everything)
• Drivetrain efficiency ≈ 0.975
• Air density calculated based on altitude (approx. 560 m to 1,730 m range); its effect is moderate and far less significant than the gradient itself

Ovaro Side Full Segment (10.1 km, 1,210 m elevation gain, avg. gradient approx. 11.9%) Estimates

Power-to-Weight Ratio	Corresponding Power for 70 kg Rider	Estimated Climb Time	Average Speed	Average Vertical Ascent Rate (VAM)
2.0 W/kg	140 W	Approx. 1 hr 59 min	Approx. 5.1 km/h	Approx. 611 m/h
2.5 W/kg	175 W	Approx. 1 hr 35 min	Approx. 6.4 km/h	Approx. 762 m/h
3.0 W/kg	210 W	Approx. 1 hr 20 min	Approx. 7.6 km/h	Approx. 912 m/h
3.5 W/kg	245 W	Approx. 1 hr 08 min	Approx. 8.9 km/h	Approx. 1,061 m/h
4.0 W/kg	280 W	Approx. 1 hr 00 min	Approx. 10.1 km/h	Approx. 1,209 m/h
4.5 W/kg	315 W	Approx. 54 min	Approx. 11.3 km/h	Approx. 1,355 m/h
5.0 W/kg	350 W	Approx. 48 min	Approx. 12.5 km/h	Approx. 1,499 m/h

The “True Hell Section” from Liariis (Approx. 8.5 km, estimated 1,150 m elevation gain, avg. gradient significantly higher than the full segment) Estimates

Power-to-Weight Ratio	Estimated Time to Pass	Average Speed
2.0 W/kg	Approx. 1 hr 52 min	Approx. 4.5 km/h
2.5 W/kg	Approx. 1 hr 30 min	Approx. 5.7 km/h
3.0 W/kg	Approx. 1 hr 15 min	Approx. 6.8 km/h
3.5 W/kg	Approx. 1 hr 04 min	Approx. 7.9 km/h
4.0 W/kg	Approx. 56 min	Approx. 9.0 km/h
5.0 W/kg	Approx. 45 min	Approx. 11.2 km/h

Sutrio Side (Estimated approx. 13.5 km, approx. 1,200 m elevation gain, avg. gradient approx. 9%, longer but relatively more consistent) Estimates

Power-to-Weight Ratio	Estimated Climb Time	Average Speed
2.0 W/kg	Approx. 2 hr 00 min	Approx. 6.7 km/h
2.5 W/kg	Approx. 1 hr 37 min	Approx. 8.4 km/h
3.0 W/kg	Approx. 1 hr 21 min	Approx. 10.0 km/h
3.5 W/kg	Approx. 1 hr 10 min	Approx. 11.6 km/h
4.0 W/kg	Approx. 1 hr 02 min	Approx. 13.1 km/h
5.0 W/kg	Approx. 50 min	Approx. 16.2 km/h

The above are physical model estimates and do not account for wind direction, road surface conditions, body size differences, refueling stops, or sudden gradient spikes; actual results will vary. Special note: the distance and gradient for the Sutrio side are “estimates,” as data varies significantly between sources; please refer to on-site signage and the latest route platform data for accuracy.

The Real Cost of the 22% Wall: A 500-Meter Example

Zoncolan’s most terrifying aspect isn’t its average gradient, but the continuous, brutally steep sections in its middle with almost no respite. Using the same model to calculate a 22% gradient section of 500 meters in isolation:

Power-to-Weight Ratio	Time to Cover This 500 m	Average Speed
2.5 W/kg	Approx. 8 min	Approx. 3.6 km/h
3.0 W/kg	Approx. 7 min	Approx. 4.3 km/h
3.5 W/kg	Approx. 6 min	Approx. 5.0 km/h

This speed is close to the brisk walking pace of an average adult. In other words, even if your power output is at the “advanced cyclist” level, on Zoncolan’s steepest sections, all you can manage is “pedaling hard, barely faster than walking”—which is precisely why many pro riders describe it as a “pure test of willpower,” rather than a climb that can be conquered through technique or tactics.

The Truth About Weight: On Extreme Steep Grades, Weight Differences Are Almost Irrelevant

Riding the Ovaro side at the same 3.0 W/kg:

Rider Weight	Corresponding Power	Estimated Time
55 kg	165 W	Approx. 1 hr 22 min
65 kg	195 W	Approx. 1 hr 20 min
70 kg	210 W	Approx. 1 hr 20 min
80 kg	240 W	Approx. 1 hr 18 min

In situations with extremely high gradients and very low speeds, air resistance is almost non-existent, and the entire power requirement is determined almost solely by the “gravitational component,” which itself is directly proportional to body weight—this means that regardless of whether you’re heavy or light, as long as the W/kg is the same, the climb time is nearly identical (in fact, due to the fixed proportion of bike weight, heavier riders even have a slight “advantage”). Zoncolan is one of the climbs in the world that best embodies the old adage that “W/kg is the only truth.”

Gear Ratios: Without the Right Gearing, You Don’t Even Qualify to Start

If Mortirolo demands “light gearing,” Zoncolan demands “ultra-light gearing.” With sustained gradients of 15% to over 20%, and almost no flatter sections to recover, a standard road bike setup almost guarantees you’ll be walking the rest of the way.

Using a 700×25c wheelset (circumference approx. 2.105 meters), here are the cadences corresponding to various gear ratios at different speeds:

Chainring×Cassette Ratio	Cadence at 4 km/h	Cadence at 5 km/h	Cadence at 6 km/h
34×32	~30 rpm	~37 rpm	~45 rpm
34×34	~32 rpm	~40 rpm	~48 rpm
30×34	~36 rpm	~45 rpm	~54 rpm
24×36 (gravel chainset with large cassette)	~46 rpm	~57 rpm	~68 rpm
24×42 (MTB-level large cassette)	~39 rpm	~49 rpm	~58 rpm

In practice, more and more amateur challengers are choosing MTB-level gearing on Zoncolan (e.g., cassettes with 40+ teeth), pushing their easiest gear well below 1:1, even down to ratios of 0.6 to 0.7. This isn’t an exaggeration—on sustained gradients approaching 20%, even quite strong amateur riders struggle to maintain a cadence above 50 rpm with traditional road gearing.

General rule: There’s only one principle for gearing on this climb—if you think your gearing is light enough, it usually isn’t light enough.

A Taiwanese Rider’s Perspective: Zoncolan Has No True Equivalent

Honestly, it’s hard to find a road in Taiwan that truly matches Zoncolan—a paved road with over six continuous kilometers hugging a 20% gradient simply doesn’t exist here. But that doesn’t mean you can’t train for it or understand its intensity.

Approximate Reference: Some industrial roads next to hiking trails, or certain steep sections (short stretches hitting 15% to 18% aren’t uncommon in Taiwan), can be used to simulate the muscular feeling of Zoncolan’s “sustained extreme steepness.” But when training, be aware: Zoncolan is relentless for “several continuous kilometers,” while most steep climbs in Taiwan “ease off after a short burst.” The way intensity accumulates is completely different.

Mental preparation matters more than physical preparation. Wuling teaches you “long-duration endurance management,” Mortirolo teaches you “repeated short bursts at your limit,” but Zoncolan teaches you something entirely different—accepting that you will be slow, accepting that your speedometer shows single digits, and accepting that all you can do is mechanically turn the pedals, lap after lap. Any thought of “pushing harder” is a luxury here, and a trap that wastes energy.

Practical Advice: If you plan to tackle Zoncolan, it’s recommended to practice “very low cadence, alternating between seated and standing positions” on any sustained steep section in Taiwan first. And be sure to actually test whether your gearing lets you maintain pedaling without losing balance on the steepest gradients—many people only discover on-site that their gear setup is completely inadequate.

Practicalities of Riding There

Season: The Carnic Alps, where Zoncolan is located, are closed or snow-covered in winter. The opening period is similar to Stelvio and Mortirolo, mostly from late spring to early autumn. Exact opening and closing dates vary each year—always check announcements from the local road authority before departing.

Temperature Warning: Due to the stuffy valley heat and extremely steep gradients, the cycling community generally advises against attempting this climb during the hottest part of the day (e.g., above 30°C). Sustained high-intensity output on near-20% gradients combined with a muggy environment significantly increases the risk of heatstroke and heat exhaustion. Starting at dawn is the safer option.

Base Location: You can combine Zoncolan with other routes in the nearby Carnic Alps, and many riders include it in the same Northern Italy cycling trip as Stelvio and Mortirolo. However, note that the driving distance between Zoncolan and the other two mountains is considerable—allow extra travel time for moving between regions.

Supplies: There are almost no shops along the Ovaro side. Be sure to carry all the water and energy supplies you’ll need for the entire climb before setting off. Estimating a high-intensity climb of nearly 1.5 to 2 hours, most people need 500 to 800 ml of fluid and 40 to 70 grams of carbohydrates per hour (individual variation is significant). But note that it’s very hard to drink while riding on such extreme gradients—plan your refueling for the slightly easier first section or make brief stops.

Equipment Check: Before departing, be sure to actually test how your easiest gear handles on extreme gradients, including whether shifting is smooth and whether the front wheel lifts off the ground when pedaling on such steep slopes (this is not an idle warning given the heavily rearward weight shift).

Safety Reminders (Please Read Carefully)

Front Wheel Lift Risk: On gradients approaching 20% or steeper, if your center of gravity shifts too far back (e.g., leaning your upper body back while climbing out of the saddle), the front wheel may briefly lift off the ground—especially dangerous on wet surfaces or in corners. It’s recommended to stay seated as your primary position on extremely steep sections, keep your weight shifted slightly forward, and keep your hands lightly on the bars to maintain steering control.

Heat Exhaustion and Heatstroke: The valley is muggy in summer, and the extreme gradients cause core body temperature to rise rapidly. If you experience dizziness, nausea, unusual fatigue, or stop sweating, stop immediately to rest, cool down, and rehydrate. In severe cases, seek medical attention promptly. This article cannot replace professional medical evaluation. Those with cardiovascular disease, a history of heatstroke, or other chronic conditions should consult a doctor before departing to assess whether this intensity of exercise is appropriate.

Tunnel Sections: Lighting is dim inside the tunnels and rock galleries in the middle section of the route. Turn on your front and rear lights in advance and slow down to avoid accidents caused by poor visibility.

Descent Risk: Some sections of Zoncolan’s descent are equally extremely steep, placing a huge burden on your braking system. Be sure to brake firmly in an intermittent manner, and check that your braking system (especially disc brake pad thickness) is in good condition before descending.

Do not race on open roads. The gradient here is already an ultimate test of physical and mental limits; any additional urge to race only adds unnecessary risk.

Common Mistakes Checklist

1. Fooled by the early gentle slopes—the mild gradient in the first 1.5 to 2 kilometers can make you misjudge the difficulty of the entire climb, leading to poor pacing later on.
2. Not bringing light enough gearing—this is the most common and most critical preparation failure on Zoncolan; many people only discover on-site that their easiest gear simply isn’t enough.
3. Starting at midday heat—the combination of valley mugginess and extreme gradients significantly raises the risk of heatstroke.
4. Leaning too far back while climbing out of the saddle—easily causes the front wheel to lift on extreme gradients, losing control.
5. Ignoring refueling timing—it’s very hard to drink while riding on extreme gradients; planning your refueling points in advance is even more important here than on Mortirolo or Stelvio.
6. Mentally trying to “power through”—on gradients approaching 20%, pushing harder buys you little time but rapidly drains your energy.

Action Checklist: From Today to Conquering the “Emperor”

Physical Preparation (8 to 12 weeks before departure — recommended to start earlier than for other legendary European climbs)

• Schedule one to two dedicated sessions per week on extremely steep gradients (15%+), focusing on “maintaining the pedal stroke without losing balance” rather than chasing speed
• Strengthen core muscle training — posture stability on extreme gradients relies heavily on core strength
• Practice a rhythm that is primarily seated with standing as a supplement, and repeatedly test how long you can sustain a stable output at very low cadence
• Training recommendations should always progress gradually; individual differences are significant. If persistent pain or unusual fatigue occurs, reduce the load and seek professional evaluation

Equipment Checklist

• Gearing: Be sure to prepare a lightest gear well below 1:1. It is recommended to actually test the handling on a steep slope before departing
• Brakes: Confirm sufficient brake pad thickness, and re-check before long descents
• Tires: Confirm adequate grip to avoid slipping on wet surfaces
• Supplies: Carry enough water and carbohydrates for the entire ride in one go — there are almost no resupply points along the route

Itinerary Planning

• Choose an early morning or cooler time of day to depart, avoiding the midday heat
• If planning a trip with multiple legendary climbs, it is recommended to give Zoncolan its own dedicated day so the body has ample recovery time
• Have a backup plan — if conditions are poor on the day (excessive heat, thunderstorms, physical discomfort), it is better to reschedule than to push through

Day-of Execution

• Deliberately keep intensity low for the first 2 km, saving energy for the hell that lies ahead
• Once entering sections above 15%, accept that the pace will be very slow, and focus on maintaining cadence and breathing rhythm
• Turn on lights and slow down in advance for tunnel sections
• After reaching the summit, rehydrate and refuel before considering celebration photos
• Use intermittent braking on the descent, and pay attention to handling on the extremely steep downhill sections

Ten kilometers, 1,200 meters, 22 percent — these numbers sound abstract, but once you ride up it, you will understand why riders call it the “Emperor.” It needs no grand scenery, nor moving history; the gradient alone is enough to make it a legend.

Related Reading

• 12.4 km, 10.5% average: Why is Mortirolo called Italy’s most painful climb
• Koppenberg: A 600-meter narrow alley of hell, the infamous climb that forces even pro riders to dismount and walk
• The Giro d’Italia and Mountain Decisives: The Mountain Epics of the Pink Jersey
• 13 km into hell: Why is Alto de l’Angliru called the most terrifying climb of the Vuelta a España