Garmin Edge 840 vs Edge 850: Which Cycling Computer Should You Buy in 2026?

Do You Need a Bike Computer for Triathlon?

If you are racing with a power meter, a dedicated cycling computer is essential — your watch alone cannot display the real-time power, cadence, speed, navigation and heart rate data you need to race intelligently. The Garmin Edge 840 and Edge 850 are the two most popular mid-to-high range options in 2026. Both are excellent; the right choice depends on how you train and what features you will actually use.

Key Features to Consider

  • Screen size and maps — Both Edge 840 and 850 share a 2.7-inch display. The 850 includes full Garmin Cycle Map for turn-by-turn navigation; the 840 has ClimbPro elevation guidance but not full turn-by-turn maps in all regions.
  • Battery life — Edge 840: up to 32 hours in GPS mode. Edge 850: up to 36 hours. Both comfortably cover an Ironman bike leg on a single charge.
  • Training load and recovery — The Edge 850 includes Training Readiness and Daily Suggested Workouts, pushing structured guidance directly from Garmin Connect. The 840 lacks this feature set.
  • Price — Edge 840 at £349.99 on Tredz; Edge 850 at £469.99 on Tredz. A £120 difference.

Head-to-Head: Edge 840 vs Edge 850

Choose the Garmin Edge 840 if: You already use a Garmin watch (Forerunner, Fenix, or Epix) that handles your training load and recovery analytics, and you want a clean, no-frills cycling head unit that does maps, power and pace without friction. The £349.99 price is significantly below the 850 and the core riding experience is near-identical. At £349.99 with a £30 saving off RRP, it is currently one of the strongest-value cycling computers in the Garmin range.

Check price on Tredz — Edge 840

Choose the Garmin Edge 850 if: Your bike computer is your primary training hub, you do not wear a GPS watch during rides, or you want the most complete Garmin cycling experience including full maps and Training Readiness. At £469.99, the Edge 850 adds four hours of extra battery life (useful for 100-mile+ training rides or full Ironman race day), full-colour Cycle Maps and the Daily Suggested Workouts feature that can sync with a structured training plan. For athletes targeting Ironman events where the bike leg can run 5-6 hours, the extra battery headroom alone justifies the premium.

Check price on Tredz — Edge 850

Buying Tips

  • Both units require a separately purchased power meter to display watt data — the head units themselves do not measure power.
  • If you already own a Garmin watch with Training Readiness, the £120 you save on the 840 vs 850 could go toward a better power meter instead.
  • Solar editions (Edge 840 Solar and 850 Solar) extend battery life further in bright conditions — worth considering for athletes training in sunny climates or targeting full Ironman distance events.

Care and Maintenance

Both units are IPX7 rated. Clean the rubber mount gasket regularly to prevent dirt build-up affecting the secure fit on the out-front mount. Charge via USB-C before every race to ensure a full battery. Store away from direct heat — dashboards in parked cars can exceed the operating temperature range in summer and degrade battery cells over time.

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