This free cycling interval timer helps you train with clear timing and sound, without an app. It runs fully in your browser, so you need no account and no sign-up, and nothing you type leaves your device. Open it on a phone, tablet or laptop where you train, and it is ready in seconds.
Cycling training uses power zones, which are bands of watts based on your FTP, the highest power you can hold for about an hour. Zone 2 builds endurance, zone 3 builds tempo, zone 4 builds threshold, and zones 5 to 7 build short, hard efforts. This tool turns your FTP and zone into a watt range for each interval, so you know exactly where to ride.
Enter your FTP in watts, pick a power zone from 1 to 7, and set the interval length in minutes, then press the start button to see the result. The tool shows the watt range for that zone, such as 152 to 180 watts for zone 2 at a 200-watt FTP. Ride inside that range for the whole interval, and repeat it for each interval in your session.
Take a rider with a 200-watt FTP doing zone 3 intervals. The tool gives 182 to 210 watts, so the rider holds about 195 watts for each 10-minute interval. Without the tool, the same rider might drift to 230 watts, which is zone 4 work, and arrive at the last interval too tired. Zones only work when you stay inside them.
The big display matters because training is physical. When you are out of breath, tired or mid-set, small text and quiet beeps fail. This tool uses a large clock, a clear phase label and a loud beep, so you can follow it from across a room or a pool deck without stopping to read.
Tip: Test your FTP first, or the zones mean nothing. A guessed FTP gives guessed zones, and the training effect will not match the plan.
Tip: Hold the middle of the zone at first. Riding at the top edge of every interval turns an endurance ride into a threshold ride.
Tip: Use a power meter or a smart trainer. Heart rate lags behind effort, so it cannot guide short intervals the way watts can.
Common question: What if I do not know my FTP? Do a 20-minute all-out test, take 95 percent of the average power, and use that as your FTP. Retest every couple of months.
Common question: Can I use it without a power meter? You can use the zones as a guide, but the numbers only work with real power data from a meter or smart trainer.
Common question: Why seven zones? Seven zones split effort finely enough to separate endurance, tempo, threshold and sprint work, which is why coaches use them.
The biggest mistake is riding every interval hard. Most training should sit in zones 2 and 3, with hard zones used sparingly. Hard every day is not hard training; it is just tired training.
This timer suits road cyclists, triathletes, indoor riders and coaches. It also suits anyone following a structured plan who wants zone targets without a spreadsheet.
On the day, charge the device the night before, open the tool early, and test the sound once before the session starts. A flat battery or a silent device in the first minute is an avoidable problem, and a one-minute test prevents it. Keep a charger nearby for long tournaments, and keep the screen bright enough to read in sunlight or under hall lights.
This tool is free to use as often as you like. Bookmark it, use it for every session, and share it with your training partners. A good timer does not make you fitter by itself, but it removes excuses, keeps sessions honest, and lets you compare this week with last week fairly.