One-Day Twin Towers 520km Extreme Ride: Full Analysis of Northeast Monsoon Tailwind and Crosswind Aerodynamics, Nighttime Body Heat Loss, and 90g Per Hour Carbohydrate Fueling

1. Introduction and Cutting-Edge Research Background

The One-Day Twin Towers (Fugui Cape Lighthouse to Eluanbi Lighthouse) is a highly symbolic long-distance challenge in the Taiwanese cycling community. The route spans approximately 520 kilometers with a cumulative elevation gain of about 2,200 to 2,600 meters. The common finishing target set by official and civilian teams is between 24 and 30 hours. This challenge is classified as “extreme riding” not simply because of the distance, but because it simultaneously combines three harsh variables: strong northeastern monsoon winds, prolonged nighttime riding, and sustained high-intensity energy output.

From the perspective of sports science research trends, the international focus on ultra-endurance sports in recent years has shifted from purely “VO2 max” and “lactate threshold” to “Metabolic Flexibility,” “Gut Training,” and “Homeostasis under Environmental Stress.” A 2023 meta-analysis published in Sports Medicine pointed out that in endurance events exceeding 12 hours, the efficiency of immediate carbohydrate supplementation and the ability to maintain core body temperature have a greater impact on final performance than the athlete’s own fitness baseline (FTP). This means that the key to completing the One-Day Twin Towers largely depends on the scientific rigor of “nutrition strategies” and “calorie management.”

Furthermore, Taiwan’s unique “northeastern monsoon” system dominates the climate of the entire western corridor from October to March each year. According to statistics from the Central Weather Administration, during periods of strong winter northeastern monsoons, the average wind speed along the Taiwan Strait coast often reaches 8 to 12 meters per second (approximately Force 5 to 6 winds), with gusts exceeding 15 meters per second. This steady north-northeast wind is both a “tailwind booster” and a “crosswind killer” for One-Day Twin Towers challengers riding southward. How to quantify the assistance and threat of this wind is the core scientific proposition of this article.

2. Core Mechanisms of Exercise Physiology and Biomechanics

2.1 Tailwind Propulsion Mechanics Model: The Multiplier Effect of Wind Speed on Forward Power

The total power required for a bicycle to move forward (( P_{total} )) can be described by the following simplified equation of motion:

[
P_{total} = P_{air} + P_{rolling} + P_{gravity} + P_{bearing}
]

Among these, aerodynamic drag power (( P_{air} )) is the most influential variable, with its formula:

[
P_{air} = 0.5 \times \rho \times C_d \times A \times (V_{ground} + V_{wind})^2 \times V_{ground}
]

• ( \rho ): Air density (approximately 1.225 kg/m³ at 15°C at sea level)
• ( C_d ): Drag coefficient (approximately 0.25 for a time trial bike with an aero position, approximately 0.5 for a road bike in standard position)
• ( A ): Frontal area (approximately 0.4 to 0.6 m²)
• ( V_{ground} ): Ground speed (m/s)
• ( V_{wind} ): Headwind speed (m/s); negative value if tailwind

Key Derivation: Assume a rider is traveling at 30 km/h (8.33 m/s). In windless conditions, their aerodynamic drag power is approximately 120 watts. If encountering a northeastern monsoon tailwind of 20 km/h (5.56 m/s), the relative wind speed drops to 2.77 m/s, and the aerodynamic drag power plummets to approximately 13 watts. This represents a saving of approximately 107 watts of additional output required from the rider, which is equivalent to increasing speed to 35-38 km/h at the same power output. In other words, a strong tailwind allows a rider to ride at “Zone 3 speed” while putting out “Zone 2 intensity.” This is the greatest physical dividend for completing the Twin Towers within 24 hours.

2.2 Crosswind Sectional Mechanics: Lateral Stability Crisis on the Miaoli Houlong and Tainan Coast

When the angle between wind direction and the direction of travel exceeds 30 degrees, the airflow generates significant side force on the bicycle, with the formula:

[
F_{side} = 0.5 \times \rho \times C_s \times A_{side} \times V_{wind}^2
]

• ( C_s ): Side force coefficient (related to wheel rim depth, frame geometry, and wind yaw angle)
• ( A_{side} ): Side profile area (rider plus bicycle approximately 0.8 to 1.2 m²)

The Miaoli Houlong section (approximately 100-120 km mark) and the Tainan Qigu to Jiangjun coastal section (approximately 330-360 km mark) are notorious “crosswind traps.” When wind speeds reach 10 meters per second (Force 5), side forces can reach 15 to 25 kilograms of force, enough to cause obvious handlebar wobble on bikes with shallow rims. The “yaw moment” in fluid dynamics causes a steering effect on the front wheel. If the rider fails to counteract this immediately with core muscles and upper body, loss of control and crashes are highly likely.

Practical Advice: In crosswind sections, lower your frontal position (hands on drops, reduce frontal area) while shifting your center of gravity rearward to increase vertical load on the front wheel and improve traction. While rims deeper than 30mm offer advantages in tailwind sections, they amplify yaw moment in strong crosswinds. Riders weighing under 70kg are advised to choose rims no deeper than 40mm.

2.3 Nighttime Low Temperatures and Additional Basal Metabolic Rate (BMR) Expenditure

One-Day Twin Towers typically departs between midnight and 4 AM, meaning 12 to 16 hours are spent in nighttime or early morning low-temperature conditions. Average winter nighttime temperatures along Taiwan’s western coast range from 12 to 18°C. Combined with the wind chill effect, the perceived temperature can plummet to 5 to 10°C.

In low-temperature environments, the human body activates shivering thermogenesis to maintain a core temperature of 37°C. Research indicates that during intense shivering, the metabolic rate can increase to 5 to 6 times the basal rate, but this heavily depletes muscle glycogen. Even without reaching the shivering threshold, a drop in skin temperature triggers the sympathetic nervous system to activate brown adipose tissue (BAT), adding an extra 40 to 80 calories of heat expenditure per hour. For a 24-hour Twin Towers ride, the additional energy expenditure caused by nighttime low temperatures is approximately 500 to 1,000 calories. If this is not replenished through nutrition, it will accelerate the accumulation of an “energy deficit,” leading to severe physical collapse in the latter stages (especially the final 50 kilometers before Eluanbi).

3. Key Parameter Field Testing and Comparative Analysis

The following provides a comparison table of power and speed under different wind speed scenarios, based on field test data and fluid dynamics models, as well as a comparison of nutrition efficiency.

Table 1: Effect of Northeastern Monsoon Wind Speed on Speed While “Maintaining 200W Output” (Road bike, C_d=0.5, A=0.5m²)

Note: This table is a theoretical model; actual conditions must account for terrain undulation and rolling resistance.

Table 2: Comparison of Energy Absorption Efficiency and Gastrointestinal Tolerance Across Different Nutrition Strategies

Field Test Conclusion: In rides exceeding 12 hours, 90 grams of carbohydrates per hour (approximately 360 calories) is the “gold standard” for maintaining blood sugar stability and delaying central fatigue. Below 60 g/hour, blood glucose levels will drop after glycogen depletion, triggering the “bonk” phenomenon.

4. Periodized Training Plan and Equipment Tuning Guide

4.1 8-Week Periodized Training Plan Before the Event (Example: 12-15 total hours per week)

Phase 1 (Weeks 1-2): Base Aerobic and Muscular Endurance Building

• Tuesday: 2.5-hour flat endurance ride, heart rate Zone 2 (60-75% FTP), maintaining cadence of 85-95 rpm.
• Thursday: Strength training (squats, deadlifts, core), focusing on single-leg stability.
• Saturday: 4-hour long ride simulating Twin Towers terrain (including climbs and flats), practicing nutrition at 60g carbs per hour.

Phase 2 (Weeks 3-5): Intensity Increase and Wind Resistance Adaptation

• Tuesday: 2-hour tempo ride, power Zone 3 (76-90% FTP), with 1-minute intervals at 120% FTP every 10 minutes.
• Thursday: Crosswind adaptation training (choose coastal routes), practicing aero position and handlebar stability in crosswinds.
• Saturday: 5-hour long ride, including 3 hours simulating high-speed tailwind cruising (above 35 km/h), increasing nutrition to 80g carbs per hour.
• Sunday: 1.5-hour recovery ride at low intensity.

Phase 3 (Weeks 6-7): Race Simulation and Night Adaptation

• Tuesday: 2-hour nighttime riding training to adapt to low temperatures and lighting equipment; test nighttime nutrition and urination rhythm.
• Thursday: High-intensity intervals (VO2 Max), 6 sets of 3 minutes at 110-120% FTP, to enhance cardiorespiratory reserve.
• Saturday: Simulate the “essential section” of One-Day Twin Towers: depart before dawn and ride 200 km, covering tailwind, crosswind, and climbing sections; fully test nutrition and clothing change strategies.
• Sunday: Complete rest or walking.

Phase 4 (Week 8): Tapering and Carbohydrate Loading

• Monday to Wednesday: Reduce volume by 50%, intensity down to Zone 1-2.
• Thursday to Friday: High-carbohydrate diet (8-10g carbs per kg body weight), complete rest or only light stretching.
• 24 hours before the event: Complete rest, replenish electrolytes and fluids, ensure adequate sleep.

4.2 Equipment Tuning and Aerodynamic Optimization

• Wheel Selection: For flat tailwind sections, 50-60mm deep-section aero wheels are recommended, but you should slow down in crosswind sections or swap the front wheel to 40mm or less. If budget is limited, a “shallow front, deep rear” configuration of 40mm front and 60mm rear offers a balance of stability and inertia.
• Riding Position: Move the saddle forward 0.5cm and lower the handlebar by 1cm to bring the back closer to horizontal, reducing frontal area (A value). Field testing shows this can reduce aerodynamic drag by 5-8%.
• Tire Pressure Setting: Use 25mm or 28mm tires with pressure set at 90-100 psi (for riders around 70kg) to reduce rolling resistance and improve comfort, minimizing road vibration fatigue during nighttime low temperatures.

5. Race Nutrition, Environmental Adaptation, and Race Day Strategies

5.1 Practical Execution Plan for 90g of Carbohydrates Per Hour

To achieve 90g of carbohydrate intake per hour, a “multi-source parallel” strategy is necessary to avoid taste fatigue and gastrointestinal burden from a single food source:

• First 20 minutes of each hour: Drink 200ml of sports drink (containing 6-8% carbohydrates, approximately 12-16g).
• 30-minute mark of each hour: Consume 1 energy gel packet (approximately 25g carbohydrates), swallowed with water.
• 45-minute mark of each hour: Eat 1/2 energy bar (approximately 20g carbohydrates) or 1 banana (approximately 25g carbohydrates).
• Top of each hour: If at a rest stop, additionally consume 1 slice of white toast with jam (approximately 15g carbohydrates).

Total: Aim for 90g per hour to ensure blood sugar stability, while also taking in 500-700ml of fluid and 400-600mg of sodium to maintain electrolyte balance.

5.2 Nighttime Low-Temperature Clothing Change Strategy and Body Temperature Management

• At departure (0-4 AM): Wear a base layer, long-sleeve jersey, windproof vest, plus fleece leg warmers and full-finger gloves. If the perceived temperature is below 10°C, add a lightweight down vest.
• 6-8 AM (sunrise): At convenience store rest points (such as Changhua or Tainan), perform the first clothing change: remove leg warmers and windproof vest, switch to a short-sleeve jersey, and apply sunscreen.
• 2-4 PM (hottest period): If temperatures exceed 25°C, consider removing the base layer and riding in just the jersey, supplementing with ice water to cool down.
• After 5 PM (Hengchun Peninsula): Put on the windproof jacket again, as the fall wind (luoshan wind) and sudden temperature drops require protection against hypothermia.

5.3 Race Day Strategy: Segment Pacing and Wind Response

Key Reminder: In the latter stages (after the 400km mark), due to declining physical condition and changing wind direction, do not force power output. Prioritize “steady output” to avoid muscle cramps or energy depletion caused by sudden high-intensity efforts.

6. Common Operational Mistakes and Scientific Myth Busting

Myth 1: The Faster You Ride in a Tailwind, the Better

Reality: Although a tailwind enhances the sense of speed, excessively chasing speed (above 45 km/h) consumes excessive power due to the non-linear increase in aerodynamic drag and rolling resistance, while also increasing crash risk. The correct strategy is to stay within your “target power zone” and let speed increase naturally, rather than forcing acceleration.

Myth 2: Only Supplementing Carbohydrates Without Electrolytes

Reality: Consuming 90g of carbohydrates per hour without adequate sodium (recommended 400-600mg/hour) can cause water retention in the intestines, impairing absorption efficiency and potentially leading to hyponatremia. Be sure to choose sports drinks containing sodium or supplement with salt tablets.

Myth 3: “Just Wear More” for Nighttime Low Temperatures

Reality: Overdressing leads to excessive sweating. Wet clothing rapidly draws away body heat during rest stops, actually increasing the risk of hypothermia. Use a “layering system” and change into dry base layers at rest points.

Myth 4: Ignoring “Gut Training”

Reality: Many riders have never practiced the 90g-per-hour carbohydrate feeding rhythm before race day, leading to gastrointestinal distress and vomiting during the event. Be sure to fully rehearse your nutrition plan during long training rides in the 4 weeks before the race, allowing gut microbiota and digestive enzymes to adapt to the high carbohydrate load.

7. Expert FAQ

Q1: How high does my FTP need to be to complete the One-Day Twin Towers?
A: Strictly speaking, the One-Day Twin Towers is not gated by a high FTP; it tests “sustained output capability” and “fatigue management.” Generally, riders are advised to have an FTP of at least 3.2 W/kg (e.g., 224W for a 70kg rider) and be able to ride continuously for over 20 hours at Zone 2 intensity. More importantly, the accumulated long-distance training volume in the 8 weeks before the event should exceed 1,500 kilometers in total.

Q2: How should I adjust my riding position when crosswinds are strong?
A: When encountering gusts, immediately move both hands to the drops, lean your upper body forward and tuck your elbows in to lower your center of gravity. Simultaneously, shift your hips slightly in the opposite direction of the wind, using your body weight to resist the side force. If crosswinds are too strong (gusts exceeding 15 m/s), decisively reduce speed to below 20 km/h, or dismount and walk. Safety always takes priority over finishing time.

Q3: During nighttime riding, how can I tell if I’m “bonking”?
A: Physiological signs of a bonk include: blurred vision, inability to concentrate, irritability, heavy and weak legs, and an abnormally decreased heart rate. At this point, immediately reduce intensity to Zone 1 and consume rapidly absorbed carbohydrates (such as sugary drinks or gels). Blood sugar should recover within 15-20 minutes. If symptoms persist, rest in a safe place for 30 minutes and eat solid food.

Q4: Does the order of drinking sports drinks versus eating gels during nutrition matter?
A: Yes, it does. It is recommended to drink the sports drink (liquid) first, then eat the gel (semi-solid), to promote gastric emptying. Consuming large amounts of solid food along with hypertonic drinks simultaneously will delay gastric emptying and cause bloating. The correct order is: liquid → semi-solid → solid, with 5-10 minute intervals between each feeding action to give the stomach time to process.

Q5: How should I recover after finishing to avoid long-term fatigue and immune suppression?
A: The 30 minutes immediately after finishing is the “golden recovery window.” Immediately consume carbohydrates at 1.2g/kg body weight and protein at 0.4g/kg body weight (e.g., chocolate milk). Over the next 24 hours, replenish fluids at 30ml per kilogram of body weight, and engage in low-intensity walking or stretching. Within 48 hours after the event, avoid alcohol and strenuous exercise, and supplement with adequate vitamin C and zinc to support the immune system. Sleep is paramount; aim for 9 hours of sleep per night for the 3 days following the event.

Conclusion: The One-Day Twin Towers is a precise contest against the laws of physics, physiological limits, and environmental variables. Only through scientific power management, intelligent application of fluid dynamics, and watertight nutrition and calorie control can the 520-kilometer long road be transformed into a controllable and deeply rewarding epic ride. May every challenger, under the blowing northeastern monsoon, safely and successfully reach the southernmost point of the nation.