Suunto watches are built for the outdoors, and the band you put on one matters more than it would on a watch that lives in an office. The good news is that Suunto uses standard quick-release spring bars, so once you know your lug width the choice opens right up.
Finding your lug width
Suunto bands are sold by width rather than by watch name, because several models share the same size.
20mm: Suunto 3 and Suunto 3 Fitness.
22mm: Suunto 5 Peak, 9 Peak, 9 Peak Pro, Race, Race S, Race 2, Run, Vertical, Vertical 2, Ocean, Core 2, and the Elementum Ventus, Terra and Aqua.
24mm: Suunto 7, Suunto 9, 9 Baro, D5, and the Spartan Sport range including Wrist HR and Wrist HR Baro.
Note that the number in the name is not the size. The Suunto 9 takes 24mm while the 9 Peak takes 22mm, which catches people out regularly.
How to measure
Take the current band off and measure the gap between the lugs with a ruler. Measure the gap rather than the band, since bands are usually cut a fraction narrower than the space they sit in.
Because these are ordinary spring bars, a band made for a Garmin, COROS or Samsung watch of the same width fits a Suunto perfectly well. That widens your options considerably.
Choosing a material
Silicone is the practical default. It sheds sweat and water, rinses clean in seconds, and handles rain and mud. If your training involves water, this is the one.
Woven nylon and alpine-style loops are lighter and considerably more breathable, which matters on long days. They also adjust continuously rather than by hole, so you can fine-tune the fit as your wrist swells over hours. The trade-off is that nylon holds water in the weave and dries slowly.
Leather suits the more traditional-looking models for everyday wear, but should stay out of water.
Stainless steel and titanium give the dressiest finish. Heavier, and not the choice for long efforts.
Cold weather is worth thinking about
Silicone stiffens noticeably in low temperatures, which makes buckling it with cold fingers harder than it sounds. Nylon stays flexible and is easier to adjust with gloves on.
Changing a Suunto band
Turn the watch over and find the small lever on the spring bar inside the band. Slide it toward the centre of the band and lift that end away from the case.
To fit the new one, seat one side of the spring bar in its lug hole first, then slide the lever and let the pin drop into the opposite hole. Tug each half afterwards to confirm.
Fit and heart-rate accuracy
Suunto watches read heart rate optically from the wrist, which depends on steady skin contact. The watch should sit snug about a finger's width above the wrist bone.
Too loose and the sensor reads motion rather than pulse, which shows as a heart rate that lags behind your effort or locks onto your cadence. Too tight restricts blood flow and skews it the other way.
Care
Rinse with fresh water after pool, ocean or muddy use. Salt and chlorine shorten the life of silicone and nylon alike. Let nylon dry fully before wearing it again.
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