Garmin Forerunner 910XT Versus Polar RCX5 Comparison Test Of Top Triathlon Watches

Recently the Heart Rate Watch Company conducted a side-by-side comparison test of the Garmin Forerunner 910XT GPS watch with the Polar RCX5 G5. Both watches are outstanding products for triathlon but there are some subtle differences that might lead athletes to favor one over the other.

The Garmin Forerunner 910XT is bigger and bulkier weighing in at about 3 ounces and measuring 2″ x 1 3/4″ whilce the Polar RCX5 weighs 1.75 ounces and is 1 1/2″ x 1 3/4″ dimensions. The Garmin you would not wear as an every day watch but the Poalr RCX5 you could. Of course the external battery for the Polar weighs about 2 ounces, so the weight difference is splitting hairs but the weight difference of the wrist unit is considerable.


The Garmin does laps and strokes in the swim plus mapping while the Polar does not, however the Polar gets heart rate in the water while the Garmin does not, this is due to the transmission frequency differences between the two products. The Garmin is waterproof while the Polar is water resistant.

To us while it is nice to know intesity in the swim and laps and strokes when you are training in the pool the metrics in the races are meaningless because you can’t look at them and the hitting and kicking in a tightly spun pack make it difficult to do much but get it over with.

We’ll call the swim a draw since heart rate is nice data to have, but so are laps and strokes for training.


The Forerunner 910XT has a quick release kit that allows you to seamless transition to the bike with no wasted time. For the Polar you can either use a bike mount, which takes about 10 seconds to get done or you can roll your wrist occasionally in the aero bars to see what is going on, but this is not ideal. We give the Garmin 910XT the edge in T-1 speed over the Polar.


On the bike the Garmin provides you with speed, distance, pedal cadence, a barometric altimeter, power output, heart rate and all the data you would expect from a high end bike computer, plus it will work with the new Garmin Vector power pedals to provide left/right power balance.

The Polar provides all the same data with the exception of power output and both watches provide a race pacing feature so, for this reason, we’ll give a slight edge to the 910XT for the bike.


Once again the Garmin 910XT with the quick release band, which is an option, comes seamlessly off the bike mount and onto your wrist taking just a few seconds to attach. The Polar you either have to undo from the bike mount or, if it is wrist bound you can do nothing. We give the transition edge to the Garmin.


Both watches get speed, distance, heart rate, do auto laps at miles and cadence with an optional cadence sensor. Polar is more accurate than the Garmin for calories and we like Polar’s heart rate features better than Garmin’s.

Both watches also contain the ability to set up drink alerts but the Garmin has a vibrating alert which we prefer to audible alerts. Both watches also work with foot pods to deliver cadence.

The Polar has an external GPS sensor but with the new clip it easily attaches easily on the side of running shorts without much bother. For running we give the edge to the Polar RCX5 because of the better heart rate features and more accurate calories.


Both watches are really fantastic triathlon products and the very best available on the market today. For us, the differences between the two would hinge on 3 major issues: 1.) Do you need watts output for the bike (then it is the 910XT by Garmin), 2.) Is heart rate in the water important? (If so, then it is the Polar), and 3.) Which of the two brands of watches are you used to? (There is no sense going up a new learning curve if you do not have to).

They are both superb watches and if you really want to talk to an expert then just call us at 866-586-7129. We test this stuff, use it, ride it, run it and are personally involved daily. Train smart and good luck!

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14 Responses to Garmin Forerunner 910XT Versus Polar RCX5 Comparison Test Of Top Triathlon Watches

  1. Desmond says:

    You should check out the Magellan Switch Up. This is gonna knock the socks out of the 910 :)

  2. Jules says:

    Were you able to test the battery life on both watches? I’ve owned both company’s predecessors (Garmin Forerunner and Polar S720) and loved the battery life on the polar and hated having to plan ahead to charge the constantly dead Garmin before workouts or trying to work the logistics for longer workout days (double workout days or long races). Any feedback on this aspect of these watches reviewed here?

    • hrwcblog says:

      Dear Jules,

      The Garmin 910XT lasts longer than any previous Garmin, so yes, around 15 to 16 hours run time is a good estimate. You might get a bit more when it is fresh, straight out of the box, but not for long in our experience.

      The Polar RCX5 can last for 9 to 12 months on a coin cell lithium battery (the wrist unit), but if you get the G5 GPS sensor you are back to the same charging every 15 plus hours. Thus with GPS the Polar has the same issues.

      In our experience foot pods just are not accurate unless there is no variation in stride length over your calibration. Mountainous terrain or run walk alternation can also mess up foot pods.


      • Norberto says:

        When you mention “[...] but if you get the G5 GPS sensor you are back to the same charging every 15 plus hours[...]” you’re talking about charging the GPS pod itself and not the RCX5 watch itself, right?

        BTW, would you consider buying an RCX5 GPS right now, or is this watch gonna be replaced soon? Although I am not a triathlon athlete, I do both cycling and running sports and I need to purchase a new HRM that will allow me to record an entire training session (preferably with a custom frequency such as 1s, 5s, 10s, etc) and that doesn’t require a full charge every 10 hours or so even when I don’t need GPS.
        For instance, does the RC5 allow to disable the GPS sensor when you don’t care about your position and still records your heart rate every 1 second?

      • hrwcblog says:

        Dear Noberto,

        Yes, the G5 GPS pod contains a lithium-ion battery that is rechargeable, so that is correct.

        The RC3 does record good data for running and cycling but is not very waterproof, you might get it wet in the rain but do not swim with it. The RCX5 is a bit of a different watch as it requires external GPS with the G5 but it can do heart rate in the water and be worn for swimming.


      • Norberto says:

        BTW, by RC5 I mean’t RC3 GPS, which I believe is one of the few Polar devices with integrated GPS.

  3. Sergio Rodriguez says:

    What about GPS accuracy? I mean distances measures. Thanks in advance

    • hrwcblog says:

      Dear Sergio,

      Yes, they are very accurate, might be off a few hundredths, maybe even a tenth of a mile depending upon the distance, but generally not much. GPS accuracy is far greater than foot pods.


      • I have to disagree with you on the accuracy, a correct calibrated Polar foot pod is actually more precise especially for data during the run e.g. speed/pace. The reson for this i simple. GPS is only accurate do 3-4 meters, a correct calibrated foot post is max 10-20 cm off.

      • hrwcblog says:

        On flat ground with a carefully calibrated foot pod, where there is no stride length variation, this is true. Unfortunately these types of conditions – flat ground, perfectly calibrated and average stride length always being consistent seldom exist here where we are because most of the terrain is up and down.

        John Yarington our chief tester has tested foot pods parallel to GPS on mountain runs (measured courses) and found foot pods to be way, way off, like in 2 miles off in a 17 mile mountain run. Now doing a 10k on flat ground I doubt he would see this type of discrepancy but if there is any type of discrepancy in your stride length, like run, walk alternation, foot pods do not handle it well because they are calibrated to one specific stride length and once you vary from that the distance errors pile up in a hurry.

        The latest GPS watches are very, very accurate – see our 5k wheel measured test on the Garmin 620 versus Suunto Ambit 2

  4. Gusthavo Marini says:

    I already own a Polar RCX5 but i find very hard to see data on bike rides… I do thing HR is important when i swim and i love it… I have the whole package (G5, bike sensors, S3 sensor) But i’m also a gadgets lover… And i was thinking of buying a CS600x to use in my bike and keep logging my workouts on … But i found the FR910XT and i loved the swim data that you can get from… Well, my question is: is there any third part software where i can mix data from both watches? Or the ideal is to use only one? I’m thinking about use a FR910XT in my bike too because it seems to be a lot better with bike mount and his pages views.

    Tks for attention.

    • hrwcblog says:

      Dear Gusthavo,

      There are third party software’s like Training Peaks Pro version where you can download data from both the Polar RCX5 and The FR910XT but you have to pay a monthly fee to use the Training Peaks Pro version.

      Rusty Squire

  5. Konstantin says:

    Hello there

    First of all, marry Christmas.
    I am doing running (about 60 kms 5 times/per week) and cyling (1-2 times/per week 35 to 50 kms each time on on routes with uphills and downhills). Ι would like to know:
    -Do I need to wear additional-external equipment (like a heart belt) with both watches or the hear rate measurement can be taken from the wrist?
    -Can I switch off the GPS on both watches if I do not need it?
    -Which software seems more easy to use in order to download training programs and learn how to use them…

    I apologize in advance for the many questions but it is my first HRM…

    Thank you in advance


    • hrwcblog says:

      Dear Konstantin,

      I would recommend a heart rate belt because strapless monitors and those that measure blood flow from the wrist are not very accurate. Garmin, Polar, Suunto and all the good manufacturers use belts but the good news is that they are all flexible fabric and comfortable so it isn’t much of an issue these days.

      Yes, you can switch off the GPS on both watches and simply select an indoor workout if you just want heart rate and calorie data.

      I think both Polar and Garmin have good software. Garmin is a bit more visual and Polar is driven by more numerical type analysis.

      No problem on the questions and if you would prefer to ask more questions and communicate with me privately then simply e-mail me at

      Rusty Squire

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