Is Garmin Forerunner 255 Good for triathlon training?

The Garmin Forerunner 255 is a mid-range GPS multisport watch that Garmin launched in 2022 as the successor to the extremely popular Forerunner 245. It exists in a family of four: the 46mm Forerunner 255, the smaller 41mm Forerunner 255S, and Music variants of each with on-watch storage for offline playlists. Both base models use a transflective MIP display that's always visible in sunlight and is controlled entirely by five physical buttons — there is no touchscreen, which many triathletes actually prefer because buttons work reliably with wet or gloved hands. The feature set is where the 255 earns its reputation. It supports multi-band GNSS (dual-frequency GPS), which meaningfully improves position accuracy in tough environments like city canyons, dense tree cover, and open water where signal reflection off the water surface can degrade fixes. It carries Garmin's full training metrics suite — VO2 max, training status, training load and load focus, recovery time, race predictor, HRV status, Body Battery, sleep score, and Training Readiness — plus daily suggested workouts and PacePro pacing strategies. It also supports Garmin Pay, incident detection, LiveTrack, and Connect IQ watch faces and data fields. Sport-wise, the Forerunner 255 has dedicated profiles for pool swim, open-water swim, bike, bike indoor, run, run indoor, track run, and — critically — Triathlon and Multisport modes that stitch swim, T1, bike, T2, and run into one activity with a lap-button press between legs. It pairs over ANT+ and Bluetooth with chest straps, power meters, speed and cadence sensors, and smart trainers, and it syncs structured workouts from Garmin Connect or third-party platforms. What it deliberately does not have, to keep the price down, is full-color mapping, a touchscreen, Wi-Fi, or music on the base model. Garmin sells the Forerunner 255 and its Music edition on Amazon, and pricing swings widely with sales — check the live listing rather than assuming list price.

Triathlon training is the act of preparing for a race in which you swim, then bike, then run, with timed transitions in between. Distances range from super-sprint and sprint races (roughly 750m swim / 20km bike / 5km run) through Olympic and 70.3 half-Ironman distances up to the full Ironman at 3.8km swim, 180km bike, and a marathon. Training is inherently multi-sport: a typical week might include three swims, three to four rides, and four to five runs, with at least one brick session where you ride and immediately run to rehearse the transition. That creates a specific set of watch requirements. You need accurate open-water swim tracking, which is genuinely hard — GPS signals are attenuated near the water's surface and your arm is often submerged, so watches that record blocky, cut-corner swim tracks are common. You need cycling data from external sensors: a power meter, speed/cadence sensor, and a chest strap, because wrist optical heart rate is notably poor during hard efforts and on cold rides. You need structured workouts that guide intervals on the run and bike without you memorizing splits, and you need load and recovery metrics that account for all three sports rather than just running. On race day, requirements tighten further. The watch has to run a multisport activity that captures the whole race including transitions, survive anywhere from about an hour to seventeen hours on a single charge, be comfortable under a wetsuit sleeve, and ideally offer enough navigation to keep you on course in an unfamiliar venue. That final point is where budget multisport watches most often fall down — basic breadcrumb navigation is workable for a marked race course but not for exploring new training routes. Understanding these requirements is what makes the Forerunner 255's strengths and gaps legible.

Start with the core question: does the Forerunner 255 actually do multisport properly? Yes. It ships with dedicated Triathlon and Multisport profiles that record swim, T1, bike, T2, and run as a single activity, with you pressing the lap button to advance between legs. The resulting activity is one file with per-leg splits — swim pace per 100m, bike speed/power/cadence, run pace and heart rate — which is exactly what you want for race analysis and for brick sessions. This is the feature that separates it from cheaper running watches, and owners consistently describe transition handling as straightforward once you've practiced it a couple of times. On the swim, the 255 covers both pool and open water. Pool swims log distance, pace per 100m, stroke type detection, and SWOLF, with auto-rest detection and drill logging. Open-water swims use GPS and record distance, pace, and stroke rate. The multi-band GNSS hardware helps here more than you'd expect — open-water tracks are notoriously ragged, and reviews and user reports consistently note that dual-frequency models produce noticeably cleaner swim lines than single-band ones. That said, no wrist watch is perfect in water, and stroke-count-based distance estimates can still under- or over-read. Many triathletes mitigate this by wearing the watch tight and high, or by pairing with a swim-focused device. On the bike, the 255 pairs with ANT+ and Bluetooth power meters, speed and cadence sensors, and smart trainers, and it supports structured workouts pushed from Garmin Connect or TrainingPeaks. It handles FTP-related metrics, normalized power, and training load contributions from rides. Two honest caveats: it isn't a bike computer, so staring at a small wrist screen while riding is impractical and arguably unsafe on the road, and it lacks the deep cycling-specific analytics of Garmin's Edge line. Most serious triathletes run a bike computer on the bars and wear the watch as a backup or for the run leg — which is a sensible split rather than a knock on the watch. On the run, the 255 is essentially a very good running watch: accurate pace, multi-band GPS, track run mode, PacePro, race predictions, daily suggested workouts, and full structured interval support. Brick sessions can be recorded either inside the multisport profile or as two separate activities. Its running metrics don't include native running power without an accessory, and advanced running dynamics (ground contact time, vertical oscillation) require a compatible chest strap — a genuine gap versus the 955/965 tier but one that a $70–130 strap closes. The metrics layer is where the 255 punches above its price. Training Readiness, HRV status, acute load, load focus, recovery time, and Body Battery give you a coherent picture of accumulated fatigue across three sports — which matters enormously in triathlon, where overreaching is easy because each individual sport feels manageable. Verified owner feedback frequently highlights morning Training Readiness and Body Battery as the most-used features day to day. The limitation is that load metrics are most trustworthy when you feed them a reliable heart rate source; wrist optical HR is mediocre during hard intervals and cold rides, so a chest strap isn't optional for serious training. Battery is the last major consideration, and it's good but not unlimited. Garmin rates the 46mm 255 at about 30 hours in GPS-only mode and roughly 16 hours with multi-band GNSS enabled. For most sprint, Olympic, and 70.3 athletes that's irrelevant. For full-distance racing, a very slow Ironman finisher approaching the 17-hour cutoff could theoretically outlast multi-band mode — the practical fix is running the race in GPS-only or all-systems mode and saving multi-band for training, which is exactly what long-course athletes report doing. The 255S, with roughly 26 hours GPS-only, is fine for everything up to a typical Ironman finish but offers less margin.