Strava AI Will Now Predict Your Race Times (but I’m Skeptical)
Strava, the superstar running and cycling app , now has a subscriber-only AI feature that predicts how fast it thinks you can run a 5K, 10K, half marathon and marathon. However, the forecasts use a different method than what you may see in other sources.
In my opinion, Strava’s forecasts look less accurate than the ones I get from Garmin and Runna, but this feature is too new to say for sure how accurate they will be for everyone else.
How to View Race Forecasts on Strava
Race forecasts are only available to Strava premium members. This membership costs $11.99 per month or $79.99 per year , and also gives you mapping tools and additional analytics such as fitness goals and metrics.
If you’re a premium member, you can find your predictions in the mobile app by going to the “You” tab (bottom right when you’re looking at the home screen) and then tapping “Progress” at the top of the screen. Just below the weekly mileage you’ll see race time predictions. This feature is currently only available on mobile devices and not in the web app.
According to Strava, to have enough data for a forecast, you need to log at least 20 runs in the last 24 weeks. Forecasts will be updated after each launch and after three days without a launch. Not only will Strava’s AI tell you how fast it thinks you can run right now, it will also tell you how that compares to your predicted time 30 days ago. Forecasts suggest that your race will be on flat terrain in good weather.
Compare Strava forecasts to other apps and formulas
You may have seen race forecasts before, perhaps on your Garmin watch or on sites like vdoto2.com . They typically use a mathematical formula, and Strava’s new predictions are based on “Athlete Intelligence,” which the company describes as a machine learning (ML) model.
Here’s what Strava says about this feature:
“Strava’s performance prediction feature is powered by a machine learning model that uses more than 100 athlete data attributes, including all-time running history and best times. Unlike other race predictors that rely on theoretical data such as estimated VO2 max, Strava uses only real-world activity data to predict race performance. The system also uses performance from athletes with similar training backgrounds, so estimated times are realistic and based on the performance of others with similar capabilities.”
In other words, the app does artificial intelligence magic: it looks at everyone else’s training and competition times, takes yours into account, and guesses how you might measure up to the overall score. I asked if Strava had done any testing to see how well the data compared to actual race results, but I still haven’t heard back. (I’ll update if I get a response.)
Of course, the predicted results I get are very different from what I see elsewhere. I’ve been logging all my runs using Garmin and Strava for a few months now, and here’s how their race time predictions compare:
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5K (3.1 miles) : Strava says I can run this race in 29:22 (up 21 seconds in the last 30 days); Garmin reports 26:02 (down 50 seconds in last 4 weeks)
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10 km (6.2 miles) : Strava predicts 1:01:50 (5 second increase); Garmin reports 55:31 (about 90 seconds late)
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Half Marathon (13.1 miles) : Strava says 2:24:57 (up 2:43); Garmin reports 2:07:09 (about three minutes less)
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Marathon (26.2 miles) : Strava reports: 5:04:04 (up 1:50); Garmin says 4:45:58 (less than 7:44)
I’m not surprised they’re different, but it’s strange that Strava thinks I’m getting slower while Garmin thinks I’m getting faster.
I don’t have any recent race data to compare it to, but I ran a 5K in 26:04 last fall. On the morning of the race, Garmin predicted I would run it in 25:50, so Garmin was only 14 seconds too optimistic. According to the same Garmin algorithm, I’m close to the same fitness level now, so I’m willing to bet that if I run a 5K this weekend, I’ll be in the low 26-minute range.
I’m currently working on a 5K plan with the Runna app and it predicts a finish time of 26:15 for my current fitness. (For other distances: 55:50, 2:08:22, 4:45:33). In my opinion, this option seems to be the most correct, at least for 5K.
I don’t trust Strava predictions
Strava’s 29:22 forecast seems too slow to me. In fact, according to the data I can find on my Strava account, last weekend I ran 5K in 30:03 (slightly slower than the 5K race forecast) during a five mile race . It wasn’t a race, and I was clearly aiming for a five-mile course, not a three-mile course.
Based on my 5K time of 26:04 (again, an older time, but probably close to my true fitness level), a simple calculator on vdoto2.com estimates that I can run the 10K in 54:10, the half in 2:00:23, and the full marathon in 4:07:43. Calculators tend to be overly optimistic, especially if you assume a shorter race time and ask it to extrapolate over longer distances. So I wouldn’t expect to run a 4:07 marathon anytime soon.
Judging by forums like the r/Strava subreddit, the jury is still out on accuracy. Here’s someone who ran a 10K in 56:34, but the app predicts 57:58, a number they just beat by almost a minute and a half. On the other hand, several people on this thread say that their Strava predictions seem to be pretty accurate. Only participation in the race will tell you for sure.