Comparing the Garmin ForeRunner 310XT and Edge 500

In July, 2009 I started using a Garmin Forerunner 310XT
T to keep track of my workouts. At first I just used the running features of the device, but shortly after I started using it for my cycling workouts as well. Previously I had been using a Polar system for cycling data capture, and soon I found the ForeRunner 310XT to be a better solution by far than the Polar one (see my previous review of the ForeRunner 310XT for more details).

Garmin Edge 500, Garmin ForeRunner 310XT and CycleOps PowerTap CPU
Garmin Edge 500, Garmin ForeRunner 310XT and CycleOps PowerTap CPU

Starting in February, 2010, I added a power meter to my cycling gadget list, and the ForeRunner proved a great partner to cycling with power, especially when compared to the PowerTap CPU unit that came with the power meter. I found the ForeRunner easy to use, accurate, and the integration with both Garmin Connect and the software solutions from TrainingPeaks more useful and easier to use than the other options.

In June, 2010, I rode the wonderful Ride the Rockies event in Colorado and used the ForeRunner 310XT to track the entire week of riding. One problem I discovered in an event like this is that the ForeRunner did not have enough onboard memory to store the entire week’s worth of riding. I discovered this before the trip and so I lugged a small netbook around with my camping gear just so I could download data after the rides. Not quite the best way to unplug on a holiday.

When Garmin announced the Garmin Edge 500 Cycling GPS
it looked like a great solution for use on my bike. Since it was cycling specific, it had a few more features designed for cycling, whereas the ForeRunner 310XT was definitely intended to be used for multi-sport activities. Since I’m always in need of a new gadget to play with, I went ahead and bought one and started using it for cycling in August, 2010.

I’ve found it to be as good as promised, but there still are times when the ForeRunner 310XT is a better choice. In the rest of this post, I’ll show you the various differences between the two devices and how one might be better than the other depending upon your circumstances.

Memory Capacity

As the memory limitation of the ForeRunner 310XT was the first thing that made me interested in the Edge 500, it’s good to start here. In my use, I’ve found the ForeRunner only has enough onboard memory to store between 24 and 36 hours of workouts – certainly not enough for a week long cycling tour. Garmin doesn’t provide specifications on how much actually memory is installed on this device, so it is a bit of a mystery to the actual capacity.

Meanwhile, the Edge 500 has 56.4 MB of flash based storage, at least according to my Mac’s view of it. I’ve got every cycling workout since I started using the Edge still stored on it – about 50 hours worth so far – and the device still has 48.7 MB of storage free! This is an amazing amount of usable storage and means even the most active cyclists will find they have room for months of data without issue. No need to take a laptop with you on holiday!

Advantage: Edge 500, handily.

Data Transfer

The data transfer mechanism is very different in the two devices. The ForeRunner 310XT uses a wireless ANT+ based data transfer mechanism, while the Edge 500 appears as a simple USB flash drive to your computer.

To exchange data between your computer and your ForeRunner 310XT you have to use a ANT+ dongle provided by Garmin that connects to your computer’s USB port along with a software application that provides drivers for the dongle. It works, and depending upon your computer configuration it is easily a setup-once-and-forget operation. You don’t need to plug in any more wires, and you just bring your ForeRunner 310XT within a few feet of the dongle and you are good to go.

In practice, though, this approach was not perfect. I found during my cycling holiday that a cheap netbook did not have enough CPU performance to reliably handle the data transfer job if it was not plugged into A/C power. That was a surprise and made downloading data from the ForeRunner a hassle during my trip, since I did not frequently have access to A/C power while camping out.

By comparison, the Edge 500 requires you to use a USB cable to physically plug the Edge 500 unit directly to a USB port on your computer. The Edge then shows up as USB flash disk, so once you are done you have to eject the device to prevent your computer from complaining.

Because the Edge 500 uses a direct USB connection, it is much more reliable and faster to do any data transfer than the ForeRunner 310XT. The USB cable is not really any more or less hassle than the ANT+ dongle, so you aren’t gaining a lot of advantage by having a wireless based data transfer mechanism.

Advantage: Edge 500, but just so.


Directly related to the data transfer mechanism is how the devices are charged. Both devices can be charged via a USB connection to a computer, or using a USB to A/C adaptor, which Garmin provides.

The primary difference here is that the ForeRunner 310XT requires a large binder-like clip that grabs onto the unit and touches two electrical connectors on the rear of the unit. Meanwhile, the Edge 500 simply uses the same USB connection for data transfer. This means a lot less bulk when traveling.

Garmin provides an excellent A/C adaptor system that includes several international wall-plug adaptors as part of their standard kit for both devices, so you’re set for all kinds of power scenarios.

Advantage: Edge 500.

Battery Life

How about battery life? Garmin says the ForeRunner 310XT’s battery life is up to 20 hours, and the Edge 500’s is up to 18 hours. In my experience these estimates are spot on. Both units battery life means you can get a few days worth of use before you need to recharge, but if you are traveling you should plan on bringing a charging solution with you.

The Edge 500 clearly consumes more power than the ForeRunner 310XT, and given that, Garmin provided more software features to help. The Edge 500 is very quick to auto power-off if it is not receiving any data, and this helps avoid unnecessary battery consumption if you’ve stopped to take a long break or after finishing a ride.

Advantage: ForeRunner 310XT, but just so.


The display on each device is similar, but there are numerous small differences.

The ForeRunner’s display is covered in glass – which I dropped and broke once, resulting in an expensive repair bill – while the Edge’s display feels like a type of plastic, but I’m not 100% positive on that.

Display Comparison of Edge 500 and ForeRunner 310XT
Display Comparison of Edge 500 and ForeRunner 310XT

Both units provide a high-contrast, easy to read display, with an optional backlight. Both units are exceptionally easy to see in outdoor light, although they are both prone to glare if the sun hits them at just the right angle – just like every other cycling computer I’ve ever used.

Each unit provides multiple pages of data, and multiple data items per page. The ForeRunner limits you to 4 data fields maximum per page, with 4 total pages, plus a workout specific page. Since the ForeRunner 310XT is a multi-sport device, each sport setting has its own independent set of customizable pages and data fields.

The Edge 500’s display is slightly taller than the ForeRunner’s, and as such you can have up to 8 data fields per page. This also means that for those pages with few fields, you can make certain key data items very large and easy to read. The Edge 500 limits you to 3 pages of data, with one additional page for workouts.

Advantage: neither. Both devices are champs with slight benefits to their intended audience.


Another software feature that is different between the two units is the Workouts feature. Both units have the ability to program complex workouts with a variety of steps, targets, repeats, etc. Both let you create courses to follow, and set alerts for time, distance, calories, or heart rate; the Edge 500 also adds support for cadence and power alerts.

The ForeRunner 310XT, however, has a great shortcut for creating interval workouts. With a quick, easy-to-use 2-page setting wizard, you can select intervals that are time or distance based, along with recoveries, and then choose the number of repetitions and if you want warm-up and cool-down intervals added. For a lot of workouts, this is all you need.

Programming the more advanced workouts in either device is not very difficult, but it’s enough steps that many people will just avoid doing it altogether. Programming these workouts is easier if you use Garmin Training Center and then download the workout to the device, but this software isn’t the best quality itself and I find myself just programming the workouts directly on the devices.

Advantage: ForeRunner 310XT.

Mounting Options

The ForeRunner 310XT is a sports watch, but there are a few different bike mounting options available as well. I’ve found when doing multi-sport activities it’s better to just leave it on your wrist, but when primarily biking, having it mounted on the bike was a better option.

ForeRunner 310XT Quick Release Kit
ForeRunner 310XT Quick Release Kit

The bike mount option I used for the ForRunner 310XT is the Garmin Quick Release Kit. This kit replaces the watch strap of the ForeRunner with one that includes a mounting bracket that then snaps into place on an adaptor that mounts directly to your bike with twist-ties. The replacement watch strap wasn’t as comfortable as the original strap that came with the ForeRunner, and it increased the width of the device slightly, but overall this is a very good mounting solution.

Garmin also sells a Forerunner Bicycle Mount Kitfor ForeRunner devices that lets strap the device to the mount directly. I haven’t used this option, but it’s a convenient way of solving the mounting problem as well.

Edge 500 with Quarter Turn Mounting Kit
Edge 500 with Quarter Turn Mounting Kit

The mounting solution for the Edge 500 is similar to the Quick Release Kit option for the ForeRunner, but attaches to the bike in a very different way. The mounting bracket itself uses high-quality bands (ethylene propylene diene monomer, a synthetic rubber!) of various sizes to secure the mounting bracket to the bike. The Edge 500 comes with a handful of different size bands and two mounting brackets, so you can easily attach it to multiple bikes. Moving a bracket to a different bike takes just seconds, but you can always buy another quarter turn bike mount kitif two mounts are not enough.

Edge 500 Bike Mount
Edge 500 Bike Mount

The design of this mounting system is simple and elegant. The bands are extremely strong and pliable enough that stretching them to secure the mounting bracket is trivial. The back of the mounting bracket rests on either your bicycle stem or handlebars using a rubber piece that keeps it from moving. Once it’s attached with the bands, the mount just isn’t going to go anywhere.  The Edge 500 slides into the bracket quickly and once its turned, it also isn’t going to fly off, even on the bumpiest of routes.

Edge 500 Bike Mount using the ForeRunner 310XT's Mount
Edge 500 Bike Mount using the ForeRunner 310XT's Mount

One nice surprise is that the quarter-turn mounting bracket design is the same between the ForeRunner 310XT’s Quick Release Kit and the Edge 500’s mounting brackets. On my road bike, I’m actually using the bracket that came with the ForeRunner’s kit instead of the Edge 500’s rubber band brackets – but only because it was already attached. There is a small screw in this mounting bracket that lets you change the orientation of the attached device, and this is one difference between the two different devices. It only takes a couple of seconds to change this, and chances are good you won’t be going back and forth between the two devices if you happen to have both (I only use the ForeRunner 310XT with its original wrist strap after buying the Edge 500).

forerunner 310xt bicycle mount
ForeRunner 310XT Bicycle Mount

The quarter-turn quick release mounting design is a great solution for putting either of these devices on your bike. It allows them to be installed and removed in about a second without having to fuss with any tools. I especially like to take off the devices whenever at a rest stop – a $200+ bike gadget that’s so easily pocketed is going to be tempting for the unscrupulous out there.

Advantage: neither, both have excellent, and compatible, options.

Training with Power

Both devices have great support for receiving data from any ANT+ enabled power meter. Over time, the firmware has been updated on both and support for showing more power data has been added. As of version 3.00 on the ForeRunner 310XT, and 2.40 on the Edge 500, the following power-related data fields are available:

  • Power (current power measurement)
  • Power – % FTP
  • Power – 30s Avg
  • Power – 3s Avg (my personal favorite)
  • Power – Avg
  • Power – kilojoules
  • Power – Lap
  • Power – Max
  • Power Zone (current power measurement)

I tend to ride with my display set to show the 3-second average power, the cadence and the current lap time. This keeps me focused on what matters most during training, but hides all the other data that might be distracting, but it ultimately depends upon what kind of ride I am doing at the time.

If you are interested in training with power, but don’t yet know much about it, start by reading Training and Racing with a Power Meter. Training with power is great fun, but the bottom line is that you either need to be analytical (okay, a bit of a geek), or have a coach that uses your power data to keep track of your progress. Otherwise, you aren’t likely to realize the benefits of the tool.

Advantage: both devices are equally capable.

Bottom Line

Both devices are excellent at what they do, and either is a powerful training companion. If you are just a bicyclist, and do no multi-sport activities, then the Edge 500 is the right choice for you. If you are into multi-sport, the ForeRunner 310XT is all that you will need, but the Edge 500 does have a few advantages, such as the large memory capacity.

The Edge 500 is also a little bit cheaper than the ForeRunner 310XT, especially if you already own a compatible heart-rate monitor or power meter.

Garmin Connect screen shot
Garmin Connect screen shot

A lot of folks are buying Garmin sports devices these days so that they can upload and share their data using Garmin’s excellent Connect website. If you haven’t tried Garmin Connect, go there and give it a shot. It’s worth the price of admission and continues to get better as Garmin adds features, albeit rather slowly.

Why is my car’s satellite navigation system so stupid?

I have two different late model (a 2006 and a 2007) GM vehicles with satellite navigation systems. Both are manufactured for GM by Denso, although they clearly have different implementations and features. The one thing they both share, however, is blatant stupidity when calculating routes.

I travel quite a bit between Houston and Austin and there are really only three reasonable ways to go: US-290; I-10 & TX-71; or I-10 & TX-183. Over the years my preference has moved from US-290 to I-10 & TX-71 as traffic along US-290 has increased on the eastern fridges of the Austin area, but the distance and time between the two is very similar and really it depends upon where in Austin you might be headed.

The GPS systems in my cars have three route options when you pick a destination: fastest, shortest and other. In both cars, the route displayed is none of the above three, but instead a long, out-of-the-way route of I-10 to Seguin before heading north on TX-123 to San Marcos, and then heading into Austin on I-35. This option is a whopping 222 miles with an estimated travel time of 3 hours and 39 minutes.

Now, the fastest route is usually not the shortest. Route calculations are supposed to take into account the actual speeds of the road segments involved, and since interstate highways are almost always faster than anything else, there is a natural preference to these roads. In this case, however, the calculation is way off. Taking I-10 to US-71 (via US-59 & TX-8 inside of Houston for those familiar with the area) is only 166 miles and estimated to take 3 hours 29 minutes according to Google. Likewise, taking US-290 is only 168 miles and estimated to take 3 hours 22 minutes.

Of course these time estimates are usually worst case scenario. Driving a few miles per hour over the speed limit I often make my trip in 2 hours and 30 minutes; worst case has been 3 hours and 10 minutes when driving 55 as an experiment (a painful one at that).

What about the shortest route option in the GPS system? That does actually route you onto I-10 & US-71 in this example, but the shortest route calculations are always incredibly stupid, too. They will often take you onto side streets for half a mile or less just to maintain the shortest possible distance. Once, when driving through Memphis, TN, the GM GPS took us on and off the interstate highway three times when driving through town, often for just a couple of blocks, just to maintain the shortest distance. Granted this is a clear example of a GPS system not being there to replace your own intelligence, but if you don’t know the town…

In the early days of consumer-level GPS systems, one of the common problems was having accurate speed data for different road segments. In western states especially, secondary highways often have the same speed limits as interstate highways. In Texas, the past 20 years has seen many of these highways improved so they route around the smaller towns, rather than going through them and stopping at every light. Consequently it is often better to take these roads than the interstates whenever possible. If the GM GPS systems do not have accurate speed data then it can account for some of this behavior, but not all.

On my normal route, once you finally hit TX-71 and the GPS decides you mean it, suddenly the estimated arrival time drops dramatically along with the distance. Is it computing this arrival time based upon your actual speed so far, or based upon the speed data of the road?

Over the years I’ve gone from absolutely wanting a satnav system in the car to wishing mine didn’t. I get much better results using a smart phone with Google Maps to get a general idea of the route to take and then consulting with it now and then if things get tricky. But for the most part, they seem poorly done enough that they just get in the way rather than help. Will the newer generations out now that provide real-time traffic data and have hard-disk based data improve their logic and performance enough that these problems are solved?

One final note for embedded systems developers: you don’t get to break the interactive response time rule of 250ms just because you are writing code for an embedded system.

Review: Garmin Forerunner 310XT

I recently purchased a Garmin Forerunner 310XT training device for use while running, cycling, and hopefully swimming. The Forerunner 310XT is a new device from Garmin, and their first multi-sport device that is waterproof and can be used for swimming, and thus triathlons.

For the past several years I have been using a Polar S725X multi-sport training device for both running and cycling. The rest of this review will compare and contrast to the Polar device since that is what I am most familiar. I have not used other GPS-based training devices before, so comparisons with those are left as an exercise for the readers.

The 310XT uses GPS to calculate your location and speed. You can then upload your data via your computer to Garmin’s Connect website, Garmin’s Training Center software, or other third-party options. After uploading you can view a map of your route, categorize and describe your activity. With the Connect website, you can easily share your activity via variety of methods, and even export the route into Google Earth.

Like most of Garmin’s training devices, you can pair the 310XT with a variety of other devices that communicate using the ANT+ Sport protocol. The 310XT will receive and record data from heart-rate monitors, bicycle speed & cadence sensors, foot-pods, and even power meters such as the PowerTap. The collected data is then joined with your route data and transmitted along with it.

The bicycle sensor option from Garmin is a combination speed & cadence sensor that mounts on the rear chainstay. This design allows one sensor unit to have two separate magnets for both the crank and the rear wheel. Compared to the Polar solution, this is much cleaner and easier to mount than two separate sensor units. The Polar cadence sensor, especially, is difficult to mount on some of the modern carbon downtubes, so the Garmin solution is a welcome change.

The speed sensor augments the GPS data so that accurate speed is recorded even when GPS signal is not available or accurate.  Garmin also sells an optional foot pod sensor that accomplishes the same when running without GPS signal, such as inside on a treadmill. I haven’t used this sensor yet as where I have run has had great GPS reception thus far.

I used a foot pod sensor with my Polar to keep track of my speed and distance while running. The downside of this type of solution is the relative inaccuracy of the data. I’d often see 10 to 20% margin of error, even after calibrating the foot pod.

My concern with a GPS-based training device would be the accuracy of the signal, especially when running under under a lot of foliage. So far, the 310XT has proven itself more than capable in this regard, and much better than other GPS devices I have used in the past. Viewing the recorded route data I’ve found very little error in position so far, and only a little bit with elevation, even when running underneath trees and bridges.

Like all GPS devices, the 310XT must determine its position when it is powered on. If you start up the 310XT inside, or where there is poor GPS signal, it can take a very long time to determine initial position, if it all. This can be an annoyance when you’re ready to start your training and you don’t have a solid 3-dimensional fix yet. The 310XT lets you begin your timer and start your activity before it has GPS signal, but it can sometimes take surprisingly long to get that initial fix. Another disadvantage of not having a fix is you won’t have accurate local time until then, either.

The Garmin 310XT has a rechargeable battery, but battery life is only approximately 20 hours of usage. My Polar S725X, by comparison, has a watch-style battery that has lasted over 5 years. In practice, a rechargeable battery solution works great, but may present a problem on multi-day activities where there is no opportunity to recharge.

Transmitting the data from the training device to your computer is done via a USB dongle that uses the ANT protocol. Garmin provides drivers and software for both PCs running Windows and Macs running OS X. The Polar solution uses an infrared based receiver that is much more difficult to work with as it requires line of sight between the training device and the infrared receiver, and Polar does not provide a software option for Macs.

For most users, Garmin’s software solutions are stellar compared to Polar’s. The big win here is Garmin’s Connect website which allows you to easily view your data online, share it with friends, and upload your data from a variety of different computers. Sharing your data is trivial, and allows your friends to view your routes, as well as being able to search for routes from others near you. The Connect website represents a modern solution for the social Internet, a great solution for most users.

Where the Polar software shines is for advanced heart-rate based training, especially with coaching assistance. Polar’s software is designed to easily share your data with a coach and receive training programs with them. Additionally, both the software and the Polar device have much more advanced features for heart-rate based training. For example, with the Polar I can run several tests to determine if I am over-training, or even what an estimate of my current VO2max. The Garmin solution only has different heart rate zones, more than adequate for most users, but you do get the impression the Polar has more science behind it.

The 310XT supports multiple bike settings, each with its own odometer. I find this feature in particular compelling as I like to keep track of my mileage for each bike separately, and as far as I could tell the Polar S725X always combined bike mileage for all bikes it had configured, rather than a separate odometer for each one. With the GPS based tracking, you don’t even necessarily need a speed/cadence sensor and you can still keep track of your bike’s mileage. This is especially compelling for mountain biking, where the rough trails often render a traditional bike computer useless.

So far, the Garmin Forerunner 310XT has been a fantastic training tool and I haven’t missed using the Polar S725X yet.

Someone finally did it…

I’ve been a GPS user since the system was first available and one thing I have always wanted was the ability for navigation software to take additional factors into account when planning a route. Most systems just offer you the ability to build routes based upon road speeds, road types (highways, toll-roads, off-road, etc.), and a choice of speed or distance goals. That’s OK, but any seasoned travel knows there’s more to it than that.

What about avoiding known traffic bottlenecks? Some navigation systems started adding that a few years ago. But one that I’ve been waiting for forever is the ability for a navigation system to route you around bad sections of town. If you are from out of town, you likely have no idea what sections of town to avoid. All the data a navigation system needs for that are already out there – crime rates by ZIP code, for example.

Honda now has a navigation system that does exactly this. Unfortunately, it is available only in Japan at the moment.

I’m sure in the overly PC society that the Western world has become it will never find its way here, which is a damn shame.