Bike Zone Calculator


Calculating Power & HR

Knowing your Functional Threshold Power (FTP) and Threshold Heart Rate (THR) is essential for effective training on the bike. Firstly, FTP and THR help establish training zones, which are different intensity ranges that correspond to specific physiological adaptations and training benefits. By knowing these values, you can accurately determine the appropriate intensity levels for your workouts, whether you’re targeting endurance, lactate threshold improvement, or maximum power development.

Additionally, FTP and THR provide benchmarks to gauge training intensity. FTP represents the maximum power output you can sustain for one hour, while THR indicates the heart rate at which your body transitions from aerobic to anaerobic energy systems. With these values, you can structure your workouts based on power or heart rate targets, ensuring that you train at the desired intensity for optimal results.

Finally, knowing your FTP and THR allows you to track your progress over time. By periodically retesting these values, you can monitor improvements in your fitness level and adjust your training accordingly. Increasing FTP indicates increased power output, while changes in THR reflect improvements in cardiovascular fitness. Overall, understanding your FTP and THR is crucial for effective training as it helps establish training zones, guides training intensity, and enables progress tracking.

Functional Threshold Power & HR Test

To calculate your threshold power and heart rate from your FTP test, enter your average power and average heart rate over the 20/30 minute duration (excluding warm up and cool down) and click calculate. You can enter this time into Training Peaks and make a note of the calculated zones for your future reference.

FTP Calculator

Training in specific zones is important because each zone targets different physiological adaptations and provides unique training benefits. Here’s a more detailed explanation of why training in each zone is important:

Zone 1 – Active Recovery and Endurance: This zone represents very low-intensity efforts. Training in Zone 1 promotes recovery, enhances aerobic capacity, and improves endurance. By training at a low intensity, you stimulate blood flow, promote muscle recovery, and build an aerobic base. It helps to improve mitochondrial density, enhance fat metabolism, and develop efficient oxygen delivery systems. Zone 1 training is essential for building a solid foundation and is often used for recovery rides or long, steady endurance workouts.

Cycling Biomechanics - Muscles Used
  1. Zone 2 – Aerobic Endurance: Zone 2 is a moderate-intensity zone where you can sustain longer efforts comfortably. Training in this zone further develops aerobic capacity, increases endurance, and improves fat utilization. It helps to strengthen the cardiovascular system, improves the efficiency of oxygen utilization, and enhances the body’s ability to clear lactate. Zone 2 workouts stimulate the development of slow-twitch muscle fibers, enhance capillary density, and promote efficient energy production. This zone is crucial for building a strong aerobic foundation, which is essential for endurance events and longer duration rides.

  2. Zone 3 – Tempo and Lactate Threshold: Zone 3 is a higher-intensity zone where you start to approach your lactate threshold. Training in this zone improves lactate clearance, raises your anaerobic threshold, and enhances your ability to sustain higher intensities. By training at or near your lactate threshold, you stimulate adaptations that delay the onset of lactate accumulation and improve your ability to maintain a high pace for extended periods. Zone 3 workouts increase the tolerance to higher levels of lactate, improve muscular endurance, and enhance the utilization of both fat and carbohydrates as fuel sources. This zone is important for improving race pace, time trialing, and developing sustainable power outputs.

  3. Zone 4 – VO2 Max: Zone 4 represents high-intensity efforts close to your maximum oxygen uptake (VO2 Max). Training in this zone targets your body’s ability to transport and utilize oxygen at its highest capacity. Zone 4 workouts increase your cardiovascular efficiency, enhance oxygen delivery to working muscles, and improve your body’s ability to buffer and clear lactate. Training in this zone improves your ability to sustain intense efforts, enhances your anaerobic capacity, and boosts overall aerobic power. Zone 4 intervals are commonly used to improve race performance, increase your ability to respond to surges, and enhance overall power output.

  4. Zone 5 – Anaerobic Capacity and Power: Zone 5 represents extremely high-intensity efforts that push you to your maximum limits. Training in this zone targets your anaerobic energy systems and develops your ability to generate and sustain high power outputs. Zone 5 workouts improve your ability to tolerate and recover from high levels of lactate, enhance muscular strength and power, and improve your sprinting and short-duration efforts. Training in this zone is important for cyclists participating in criteriums, sprints, and other explosive efforts that require rapid accelerations and short bursts of power.

It’s important to note that the time spent in Zones 4 and 5 should be relatively shorter compared to the time spent in Zones 1, 2, and 3, as the high-intensity nature of these zones can induce greater fatigue and require adequate recovery. Incorporating training in each zone, including Zones 4 and 5, helps target different physiological systems, develop a well-rounded fitness profile, and optimize performance across various cycling disciplines and race scenarios.

Remember to update your zones in your training plan and other training software for accurate training.

How to update your zones


Garmin Connect


How To Test?

To test your zones I look at 20 minute tough efforts in each discipline to calculate your threshold power, pace and heart rate. It takes some practice and the more you do it the easier it becomes to gauge effort.

I recommend retesting regularly, typically every 4-8 weeks depending on the athlete and their goals. This is a great way to monitor improvements and update your zones so your training progresses along with your updated fitness.

I have a training week available to purchase on Training Peaks for $4.95 using the link below, this will link to your sports watch and Zwift so you can test yourself easily at home.