Your first 30 days with the Garmin Forerunner 55

Twenty minutes on the first evening. Everything the Forerunner 55 will tell you for the next month is built on a heart-rate trace, a satellite mode and a screen setting, and all three are decided here.

1. 1

   Put it where the sensor works

   A finger’s width above the wrist bone, one notch tighter than feels natural for the first week, sensor window clean. The Forerunner 55 has a 42 mm case and wants a wrist of about 143 mm or more to sit flat; on a smaller wrist it rocks, and a rocking sensor is the source of half the strange numbers in month one. See wrist and case size .

2. 2

   Set your maximum heart rate, or clear it

   Every zone, every training-effect score and most of the load figures hang off this one number. If you know it from a recent hard effort, enter it. If you do not, delete the age-based default rather than leaving it: a wrong maximum quietly miscounts every run.

3. 3

   Leave the GPS mode alone

   The Forerunner 55 has one satellite mode, which is one fewer thing to configure. Its 20 h GPS figure is the one to plan long days around.

4. 4

   Turn the backlight down, not off

   The Forerunner 55 has a transflective screen: it is lit by the sky and costs almost nothing to leave on, which is most of why it exists. Set the backlight to gesture and the lowest brightness you can read; the quoted 20 h already assumes the screen is on.

5. 5

   Build one data screen you will actually read

   Pace, heart rate, distance, time. Four fields, one screen, big digits. Everything else can be a second screen you swipe to when you want it. The stock screens show too much and you will read none of it at speed.

Garmin’s training suite on the Forerunner 55 starts producing figures after the first run and the first night. These are the ones that arrive first, with what each one needs before it means anything.

• Body Battery — from the first night. A 0–100 reserve estimated from heart-rate variability, stress and sleep. It reads high in the morning and drains through the day; the shape is more useful than the number, and it needs about a week before the morning figure is worth comparing day to day.
• A VO2max estimate — after the first outdoor run of ten minutes or more with GPS and heart rate. It is a fitness proxy derived from pace against heart rate, so it is only as good as the heart-rate trace: a loose watch or a cold wrist produces a low number, not a slow runner.
• Recovery time — after the first workout. Hours until the next hard session, counted down from the last one. In week one it is a generic estimate; it sharpens once the watch has your fitness level.
• Daily suggested workouts and a race predictor — both live from day one, both generic until the VO2max settles.

The second layer of figures is where the Forerunner 55 earns its price, and where a new owner is most often misled — because each of them shows a value before it has the data to justify one. What follows is what each needs, on this maker’s system: the baseline takes about three weeks.

• Sleep score — meaningful after a few nights, but only if the watch is on your wrist at night. Everything overnight depends on that.
• HRV Status — Garmin says up to 19 nights before it reports a baseline; call it about three weeks. Until then the field says “calibrating”, and any readiness figure that leans on it is leaning on nothing.
• Nothing else. This tier is deliberately simple: VO2max, Body Battery, recovery time, suggested workouts and a race predictor. The load-and-readiness layer is what the full-suite watches add, and a first month without it is not a worse month.

By the end of the month the VO2max will have stopped jumping around and the Body Battery will have a recognisable daily shape. That is the point at which the watch starts to be describing you rather than an average person.

• Watch the trend, not the day. One low Body Battery or one poor sleep score is noise; a week of them is information.
• Wear it to bed or ignore the recovery half. HRV, sleep and the morning readiness all come from overnight data; without it they are guesswork dressed as numbers.
• A VO2max that drops in the first weeks is almost always the heart-rate trace improving as you learn to wear the watch, not fitness falling.
• Override it when you know better. The model cannot see that you moved house, sat on a plane or ran into a headwind — see training load and readiness, and how much to believe .

Two figures on the Forerunner 55 are worth writing down at the end of the month, because they are the ones you will compare against later: the fitness estimate and, if the watch shows one, the morning recovery figure. Everything else is a snapshot.

These are the Forerunner 55’s own figures, and the arithmetic the site’s battery guide applies to them. The quoted number is the best case; the settings you chose above decide which line you actually live on.

For a race, take a further fifth off for a cold day and then add your margin — or let the battery planner do the sum for the Forerunner 55 with your settings and your finish time. Everyday battery of 14 days means the charger is a weekly appointment at most.

The finder ranks the Forerunner 55 on the same figures this page uses. Its one-line verdict: The honest floor: everything a new runner needs and nothing else.

Where it is strong

• Light enough to forget on a small wrist.
• Suggested workouts and a proper recovery time.
• The screen you can read in full sun.

What it gives up

• No barometric altimeter, so climb is GPS-derived.
• No navigation of any kind.

If any of that is news after buying it, the finder will show you what the trade-off bought you — and what sat next to it in the ranking.