Latest revision as of 13:58, 10 May 2017

Garmin 910XT

The Garmin 910XT is an update to the Garmin 310XT with extra features, but it's more expensive. Probably the most useful feature for most runners is the calculation of Training Effect, and the altimeter. The 910XT has been replaced by the Garmin 920XT which offers a lot more features, but its release has also dropped the price of the 910XT. For a simple evaluation of a GPS watch, I look at how well it can answer some basic questions:

• How far did I run? This is the most basic question, and the Garmin 910XT has good GPS accuracy. It will give you a better idea than most watches how far you've gone.
• How fast am I running? Knowing how fast you're running can be a nice to know, or it can be vital for your training or race performance. Because of the nature of GPS, watches that rely on GPS signal alone tend to have serious problems with current pace. Thankfully, the 910XT is one of the few devices that will display current Pace From A Footpod while getting all other data from GPS.
• Where am I? The Garmin 910XT has some basic navigation functions.
  • Track Outline. There is a display of where you've run, rather like a breadcrumb trail. There are no maps, so this is just the outline on its own without any context. However, you can use it to backtrack along your path.
  • Course Outline. This is an outline of a route that can be downloaded. I've found this useful during ultras or in unfamiliar cities where I've needed to know where to go.
  • Back To Start. This is a simple arrow point to your starting point, so it won't help you backtrack.
  • Back To Waypoint. You can mark a location and use the arrow to point to it later. Again, this is a simple "as the crow flies" pointer.
  • GPS "Compass". There's no magnetic compass so you have to be moving for the GPS to give you a sense of direction.
• What's my cadence? Cadence is one of the most critical and often overlooked aspects of running. If you get your Cadence right, many other things naturally fall into place. The Garmin 910XT supports Cadence via a Footpod, but has no alerts nor does it have an internal accelerometer to estimate Cadence.

For ultramarathon running the Garmin 910XT has the battery life to suffice for shorter ultras, but if you expect to be moving during the Second Dawn you may need to look elsewhere. (You can turn off GPS and use a Footpod; if you're okay with that compromise, the 910XT will last for days.) See Watches for Ultrarunning for more details.

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1 Garmin 910XT Pros

• A great feature is the ability to use the optional Footpod to display your current pace while using GPS for overall pace, distance and route. Only the 910XT, 910XT and Garmin 610 can do this.
• The 910XT has good GPS Accuracy, and is better than many more recent devices.
• When the 910XT starts up in the same location as the last run it will acquire satellites quickly, though if you've travelled 100s of miles/Km then it can take quite a few minutes.
• The larger size allows for a larger display that's easy to read, even with four data items displayed.
• The 910XT will display the route you've run, though it does not have any built in maps. You can also upload courses and display them which is great for trail ultramarathons.
• There are several optional extras for the 910XT, including a Footpod and heart rate strap. For cyclists there is also a speed/cadence sensor and it works with various power sensors.
• The 910XT will alert you when a metric is out of range, including an alert for Cadence that is really useful and one of my favorite features.
• The 910XT displays and records Training Effect, an indicator of how hard or effective a training session is.
• The 910XT can record swimming, but it does this with an accelerometer rather than GPS. You have to tell the 910XT how long the pool is, but it will detect each lap, as well as your stroke.
• The 910XT has a barometric altimeter, which is far more accurate at recording altitude changes than GPS.
• The 910XT will not display Heart Rate Variability but it is possible for it to record Heart Rate Variability for later analysis. This recording can be enabled from the firstbeat.com ATHELTE software (there's a free trial).

2 Garmin 910XT Cons

• Some people find the 910XT to be rather large, and it is much larger than a normal watch.
• The battery life is good for about 16-20 hours, which is enough for most people. Ultrarunners doing 100 mile or longer races will find this a problem, though it is possible to recharge it while in use.
• For races where the GPS track is not important, you can extend the battery life by turning off the GPS receiver and use the Footpod. After 24 hours of running I still have most of the battery left. If you're running on a reasonable smooth surface, the Footpod is often more accurate than GPS.
• The biggest downside for most people over the 310XT is the price, which is significantly more than the 310XT.

3 What's Missing

While I don't consider these missing features as 'cons', it's worth understanding the features that are missing compared with other watches.

• GPS Pre-cache. Most of the time, even GPS watches without satellite pre-cache will locate the GPS signal quite quickly provided you've not traveled far from the position of the watch was last used. However, those times when you have traveled, a GPS watch without satellite pre-cache can take several minutes to locate the GPS signal. This can be remarkably annoying when you're freezing cold and wanting to start your run to warm up.
• Downloadable Apps. Smart watches have got is used to the idea of a device that can be extended with new functionality, and this concept is being introduced to running watches.
• Extended battery life. Some porches can extend the battery life by turning the GPS reception off for short periods. This can dramatically reduce GPS accuracy, but it's a useful trade-off for some ultramarathons.
• Graphs. Instead of simply displaying a numeric value for things like heart rate, some watches will display a graph of the value over time, giving you a sense of how things are progressing.
• Running Dynamics. Some of the newer Garmin watches can show and record Vertical Oscillation (VO) and Ground Contact Time (GCT).
• WiFi/Bluetooth Uploads. While the automatic upload of workouts via WiFi or Bluetooth to a Smartphone is nice, the upload will typically only go to the manufacturers web site.
• Web Configuration. Some watches allow you to setup the configuration via a web site, and then download your changes. This is vastly easier than fiddling with the watch.

4 Comparison Table

I evaluate running watches in three distinct ways. Firstly, you can use a watch on its own, without any kind of Footpod. This is probably the most common way runners use their watch, but you miss out on a lot. The second rating is with a standard Footpod that is available quite cheaply. These Footpod's can be reasonably accurate once the calibrated, but calibration is a little tedious. The final evaluation is with the Stryd Footpod, which is vastly more accurate than any other type of Footpod, or and more accurate than GPS. The table below looks at the score, and the value for money of each watch for each of the three conditions. (I’ve also tested the Apple Watch 3, but I’ve not included it in these tables as it’s not really a running watch.)

The score is the sum of how well each watch can answer the four basic questions (how far, how fast, where are you, what's your cadence), plus some bonus points.

1. The "How far you've run" will be based on GPS only for "without Footpod" and "with Standard Footpod", but based on Stryd if supported in the "with Stryd Footpod" table..
2. How fast you're running assumes you're using a Footpod if it's supported, otherwise the rating is 0-2 based on GPS accuracy.
3. The "Where are you?" is based on various navigation features such as back to start, breadcrumbs, and preloaded maps. For some watches, you have to turn GPS off to get the benefit of Stryd, so those watches have worse "where are you scores" with Stryd than without.
4. The cadence score uses 1 point for an internal cadence sensor, 2 points for footpod support, 1 point for support from chest strap cadence, and 1 point for cadence alerts.
5. I give 1-2 bonus points for application support, 1-2 bonus points for data upload, 1-2 bonus points for Optical Heart Rate Monitoring, and 0-1 bonus points for battery life.
6. Value for money is the score divided by the price (at the time I last updated the table.) Your needs may be different, so you might weight the different aspects of the watches differently, or be basing your decision on different criteria totally. Hopefully this table will give you a good starting point for your decision.

4.1 Score Breakdown without a Footpod

4.2 Score Breakdown with a Standard Footpod

4.3 Score Breakdown with a Stryd Footpod

4.4 Basic Features

5 Navigation Features

For "navigation":

• Color Maps gives you full color maps, rather like a smart phone, with roads and paths marked out.
• Track Outline is a display of where you've run, rather like a breadcrumb trail. If there are maps, the outline is superimposed otherwise this is just the outline on its own without any context.
• Course Outline is an outline of a route that can be downloaded. I've found this useful during ultras or in unfamiliar cities where I've needed to know where to go.
• Back To Start is a simple arrow point to your starting point, so it won't help you backtrack.
• Back To Waypoint returns you to a previously marked location using a simple arrow to point.
• Compass. A magnetic compass can help you orient yourself or the map. Without a magnetic compass you have to be moving for the GPS to give you a sense of direction.

(Older Reviews: Polar RC3 GPS, Soleus 1.0, Motorola Motoactv.)