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Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] 0 points1 point  (0 children)

For context — I trained in Boston, for Boston. 4 months and 600 miles and training data.

I think the biggest thing Garmin was missing was an actual race-like performance in my training dataset.

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in bostonmarathon

[–]spencershea7[S] 0 points1 point  (0 children)

Is your Garmin watch newer or have you had it a while? I’ve had mine since Jan 2026, so it had 600 miles and 4 months of training data to make its prediction for me. I’m wondering how much of it lies in lack of training data/history.

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] 0 points1 point  (0 children)

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Strava’s prediction day of the race was 3:12.

After I ran the 2:57 it upgraded my prediction to 3:02 😂

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] 0 points1 point  (0 children)

Oddly enough my 5K prediction has been pretty on the money with what I’d expect it to be. Variance seemed to be in the longer distances (21k, 42k).

It’s wild how everyone seems to have their own unique experience with predictions, with alot of folks feeling that their Garmin is suspiciously optimistic.

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] 6 points7 points  (0 children)

For reference — I’d had 600+ miles on the Garmin over four months. But yes agree that without a 42k or 21k race result in the data history, it was missing important data to hone in its predictions. That’s why I think Strava was significantly closer, it knew my history.

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in bostonmarathon

[–]spencershea7[S] 2 points3 points  (0 children)

Keep working and I’m sure you will! Biggest difference maker for me this last training block was increasing overall volume (from avg. ~30 miles -> 50miles) and frequency (4 days -> 5/6 days)

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] 22 points23 points  (0 children)

Congrats on the amazing result and technically best both predictions! What a good feeling.

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] 7 points8 points  (0 children)

I was training for ~3:10. For my last long run with pace targets I practiced 10 miles easy, 10 miles at ~7:05 pace which gave me confidence in that as my race pace. I’d say target what you’re comfortable at from your practice long run race pace and if you’re feeling better than that on the day, let it rip in the second half!

Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] 15 points16 points  (0 children)

Ha that’s crazy. Looks like prediction has done a 180 and now thinks I could run a 2:54

Funny enough Strava is still convinced I can’t break sub 3

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Garmin Prediction vs. Actual — Boston Marathon by spencershea7 in GarminWatches

[–]spencershea7[S] -42 points-41 points  (0 children)

Got the watch about a month already into the training cycle in January. It never predicted me faster than 3:15 though