Garmin Forerunner 265 Best Settings for Triathlon and Marathon Training

Grit & Mileage
Mar 11
7 min read

Updated: Mar 17

The Garmin Forerunner 265 is one of the most capable GPS watches on the market for endurance athletes, but out of the box, its default settings leave a lot of performance on the table. After training with the 265 through a full marathon cycle and now into Ironman prep, I've dialed in the exact settings that give me the data I actually need on race day without the clutter I don't.

This guide walks you through my recommended settings for triathlon training, marathon training, and race day — plus the battery optimization tricks that'll keep your watch alive through a full Ironman.

Why the Forerunner 265 Works for Multisport Athletes

Before diving into specific settings, here's why the 265 is such a strong choice for triathlon and marathon training. At $150 less than the Forerunner 965, you get the same GPS chipset, the same heart rate sensor, and the same training metrics. The main things you give up are onboard maps and some battery life. For most athletes who aren't navigating backcountry trails mid-race, that's a trade worth making.

I covered the full 265 vs 965 comparison in a separate post, but the short version is: unless you need maps for ultra-distance trail navigation, the 265 gives you 90% of the 965's capability for $150 less.

The First Settings to Change Out of the Box

When you first unbox the 265, Garmin's defaults are designed for casual fitness users. Here are the settings I changed immediately.

Auto Lap: Keep this on for running (default 1 mile or 1 km depending on your unit preference). For cycling, I switched to manual lap only since I prefer to lap at specific course markers rather than arbitrary distances.

Auto Pause: Turn this OFF for racing. During training runs in the city with stoplights, auto pause is convenient. But for races and key workouts, you want total elapsed time visible at all times. I have two separate activity profiles — one for daily training (auto pause on) and one for racing (auto pause off).

Data Screens: This is where most people leave too many defaults. You don't need six data fields crammed onto one screen. Here's what I run.

Marathon Race Day Screen Setup

For marathon race day, I use a three-screen setup. The primary screen shows three fields: current pace, lap pace, and distance. That's it. During a marathon, you need to know how fast you're going right now, how fast your last mile was, and how far you've run. Everything else is noise.

The second screen shows heart rate, heart rate zone, and time of day. I glance at this maybe three times during a race — at miles 6, 13, and 20 — just to make sure I'm not redlining too early.

The third screen shows total time, calories, and cadence. Honestly I almost never look at this one during a race, but cadence is useful data to review post-race.

The key principle: fewer fields per screen, larger text, and only data you'll actually act on during the race. If a metric won't change your pacing decision, it doesn't belong on your race screen.

Triathlon and Multisport Activity Settings

The Forerunner 265 has a built-in triathlon activity mode that automatically handles swim-bike-run transitions. Here's how I set mine up.

Swim Settings: I use pool swim mode for training and open water swim for race day. For pool swim, make sure your pool length is set correctly — the 265 counts lengths automatically and even detects stroke type. My key data fields for swim training are interval distance, interval pace, stroke count, and total distance. For open water, I display distance, pace, heart rate, and time of day.

One critical setting for triathlon: enable Auto Sport Change. This lets the watch automatically transition between swim, bike, and run segments when it detects you've started moving differently. Some people prefer manual transitions so they can see exact T1 and T2 times, but I prefer auto since fumbling with my watch in transition costs more time than it saves.

Bike Settings: For the cycling segment, I display speed, distance, heart rate, and cadence on my primary screen. If you use a power meter (I don't yet, but it's on the list), you'd want to add power and 3-second average power. The 265 pairs with ANT+ and Bluetooth power meters without issue.

Set your auto lap to manual for bike segments. Triathlon bike courses have specific aid station placements and terrain changes that make distance-based auto laps meaningless.

Run Settings (Off the Bike): The most important setting for the triathlon run is having a separate activity profile from your standalone marathon profile. Your triathlon run pace will be 15-30 seconds per mile slower than your fresh marathon pace, and seeing lap paces that feel "slow" compared to your marathon training can mess with your head. I set up a separate Tri Run profile with adjusted pace alerts.

Battery Optimization for Long-Course Racing

Battery life is the 265's one weakness for Ironman-distance racing. Garmin rates it at roughly 20 hours in GPS mode, but real-world usage with optical heart rate, connected sensors, and notifications running eats into that. Here's how to stretch it.

Turn off phone notifications during the race. This alone saves significant battery. Go to Settings, then Notifications, and toggle all notifications off. You can also enable Do Not Disturb mode.

Switch GPS mode from All Systems to GPS Only for the bike leg. You don't need multi-GNSS accuracy when you're on a road course doing consistent speed. This saves roughly 15-20% battery on a long bike leg.

Reduce screen brightness to the minimum you can still read comfortably. The AMOLED screen on the 265 is gorgeous but it's a battery hog.

Turn off the always-on display. Use the raise-to-wake gesture instead. This is the single biggest battery saver on the 265.

Disable Wi-Fi and pulse oximeter during the race. Neither serves any purpose mid-race and both drain battery.

With these optimizations, I've gotten 14+ hours out of a single charge on a long training day simulating Ironman pacing. That should be plenty for most athletes finishing an Ironman in under 14 hours. If you're expecting a longer day, charge the watch fully the night before AND top it off the morning of the race.

Heart Rate Zone Settings

Garmin's default heart rate zones are calculated from a generic formula based on your age. These are almost certainly wrong for you. Go to Settings, User Profile, Heart Rate Zones, and set them based on your actual lactate threshold heart rate.

If you don't know your LTHR, the simplest field test is a 30-minute all-out solo time trial (running or cycling). Your average heart rate for the last 20 minutes of that effort is a solid approximation of your LTHR. Then use the standard zone percentages: Zone 1 is below 85% of LTHR, Zone 2 is 85-89%, Zone 3 is 90-94%, Zone 4 is 95-99%, and Zone 5 is 100% and above.

Getting your zones dialed in makes every heart rate-based metric on the watch actually useful — training effect, recovery time estimates, and race day pacing all improve dramatically.

Training Features Worth Enabling

A few built-in features that most people overlook.

Morning Report: Enable this. Every morning when you put on your watch, it shows your sleep score, HRV status, training readiness, and any scheduled workouts. It takes five seconds to check and gives you a quick pulse on whether today should be a hard day or an easy day.

Training Readiness Score: This combines sleep, recovery, HRV, and training load into a single score. I don't let it dictate my training plan, but if it's below 30 on a day I had a hard workout planned, I'll seriously consider swapping in an easy day.

Race Predictor: Take this with a grain of salt, but it's useful directionally. The 265 predicts your finish times for 5K, 10K, half marathon, and marathon based on your VO2 max estimate and training history. Mine was within two minutes of my actual 3:26 marathon finish, so the algorithm is surprisingly decent.

Course Navigation for Race Day: Even though the 265 doesn't have full-color maps like the 965, you can still load GPX course files. The watch will show a breadcrumb trail and alert you if you go off course. For triathlon race day, download the official course GPX file from the race website and load it the night before. This is especially useful on bike courses where missed turns can cost you miles.

Final Thoughts

The Garmin Forerunner 265 doesn't need a wall of complex settings to perform well. The biggest gains come from simplifying your data screens to show only what you'll act on, setting accurate heart rate zones based on your actual physiology, and optimizing battery for long-course racing.

If you're deciding between the 265 and the 965, I wrote a detailed comparison with my recommendation here on the site. And if you're training for your first Ironman, check out my full Ironman Florida gear and preparation guide for the complete race day setup beyond just the watch.

The 265 is the best value in GPS multisport watches right now. Set it up right and it'll carry you from 5K training all the way through a full Ironman.

Gear That Pairs With Your 265

Now that your watch settings are dialed in, here are the accessories I use alongside my Forerunner 265 for training and race day:

Garmin HRM-Pro Plus — chest strap heart rate monitor for accurate zone training
Shokz OpenRun Pro 2 — bone conduction headphones for music on long runs
Garmin Running Dynamics Pod — clips to your waistband for cadence, ground contact time, and vertical oscillation data
GU Energy Gels (24-pack) — my go-to race and long run fueling

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