Gear Review: Garmin 405 GPS Watch

It wasn't all that long ago that if you wanted to know how far a run was, you had two options: you could either drive your running routes and check your car odometer, or you could time the run and estimate how fast you were running, then divide the time by your estimated pace to get the miles. The first method was often inconvenient. Who really has time to drive all their routes? And what if your routes take a shortcut across someone's yard or go down a trail or something? And the second method was woefully inaccurate. I can't even tell you how many "long 7s" the Bucknell women's team had, because we decided to assume we were always running 8:00 mile pace. Only it was the fastest "8:00 pace" in the history of the world, and a lot of those runs were 8 miles or longer. Then came MapMyRUN. Now you could figure out how far your runs were by tracing the route on your computer. It still was a little problematic if you ran on trails or MUPs, but it was a huge improvement over the "divide by your pace" technique. It even showed little mile markers on the map, which should have made figuring out mileage for tempo runs a lot easier...except that a mile marker in the middle of a long road on a computer is nearly impossible to figure out in the real world. And for some reason, my team still didn't adopt this, so our distances were still short (which makes me wonder what my mileage really was in college...hmm...). Then in fall '06, one of the freshmen showed up for cruise intervals with this big freaking computer on her wrist and told us we were running 20 seconds too fast per mile. No one believed her...but then our coach yelled at us for going too fast. That was the Garmin Forerunner 205. A few years later, a sleeker version was introduced: the Garmin Forerunner 405.

The Garmin 405 is a wrist-top GPS receiver. There's a very good explanation of how GPS works on Garmin's website. Basically, a GPS receiver works by locating and receiving transmitted signals from four or more of the 24 GPS satellites that are orbiting the earth. The GPS receiver compares the time the signal was transmitted to the time the signal was received to determine the distance from the receiver to the satellite. This information can be combined with the information from other satellites to estimate the location of the receiver. By comparing multiple signals over time, the GPS receiver can determine how far you've gone, and this information can then be used to determine your pace.

The Garmin 405 is split into three screens that can be set to display whatever you deem important. I currently have mine set to time, distance, and instantaneous pace (the default when you get the watch...I don't have the heart rate monitor version and can't think of anything that would be more useful anyway). It's controlled primarily by the bezel that surrounds the face of the watch, though it also has a start/stop and lap button. Anyone who's used an iPod Classic knows how the bezel works, as it's operated by touch. It can also be wirelessly synced with your computer, and you can analyze your run data and/or upload it to any Garmin compatible training log.

The Garmin 405 is a lot nicer looking than the old 205 and 305, though it's still a big and bulky watch. It might look alright on a large man's wrist, but it's not something that a small woman would want to use as a regular watch. Additionally, the plastic immediately above and below the watch's face is hard and will not bend around your wrist. Clearly, this watch is a training tool, not a fashion accessory. Don't buy it expecting to wear it around as an every day watch. Buy it intending to put it on to run and take it off when the run is over.

Garmin 405 compared to a Nike Triax Fury, which is also a fairly large watch.

Garmin 405s seem to be very accurate with each other. On the numerous runs that I've run with training partners who also had a 405, the Garmins always seem to be within a few tenths of a mile of each other. Additionally, when I repeat routes with the 405, the Garmin always comes up with a similar number (again, within a few tenths of a mile per 8-12 mile run). I also have taken it on a track to measure it's accuracy, and the numbers are very, very good. The 405 is slightly less accurate on trails. This may be partially due to trees interfering with the GPS signal and partially due to the fact that trails tend to be winding, and the GPS measures straight line secants between points when calculating distance (really chords, but does anyone other than a math geek know what a chord is?). Still, the 405 seems to receive signals more often than the older 205 and 305, making its straight line estimations more accurate.

GPS units measure secants between points. The black line represents the path run, while the red line represents the path the GPS measured.

In addition to trees, cloud cover can also slightly decrease the accuracy of the 405. This is seen most in the instantaneous pace, which uses the last couple signals to estimate how fast you are running at that moment in time. There have been a few times when I'll see 9:00 pace come up during a tempo run due to the signal being lost for a moment. However, it seems to figure it out in the end, and the average pace should be pretty accurate (since the distance is usually very close, and the stopwatch is independent from the GPS). This can be remedied by having the watch display pace per mile (or pace per 800m or whatever you choose) instead of instantaneous pace. However, I feel that the instantaneous pace is a nice feature and accurate enough that I leave it as one of the three screens on my watch (my friend Molly may disagree though, and I believe she sets hers for average pace per 800m).

My biggest complaint about the 405 is the fact that it is not waterproof at all. The website claims that the 405 is "water resistant," but I'm pretty sure that means that water won't get inside the watch and break it, not that it functions properly if it gets wet. The tiniest bit of sweat or rain will cause the bezel to go haywire. If you remembered to lock the bezel beforehand, you'll be fine. However, if you forgot to lock the bezel, it will start beeping wildly and will scroll through screens (and Murphy's Law says it will get stuck on the useless virtual partner screen, and the wet bezel will not allow you to change it back to a useful screen). The new Forerunner 410 is supposed to fix this problem, but I have not had an opportunity to try it out. The other possible concern is that the 405 has a relatively short battery life (8 hours in training mode), so you really have to remember to charge it often.

The Garmin watches are one of those things that once you have, you wonder how you ever ran without. I've found that it's an indispensable training tool for tempo runs and other long interval workouts, as well as for measuring distance on long runs. However, I'd caution you not to let it tempt you to run your easy runs too hard, which can lead to compromised quality workouts. I leave mine at home on easy and recovery days. Finally, the 405 is a very complex watch with tons of features. I've found that only a few of them are useful to me. Depending on which features you think you'll use the most, you may be able to get away with a less expensive Forerunner 110 or 210. However, they really are not that much cheaper, and many people will recommend you spend the extra $50 and get a "real" Forerunner.

This may seem obvious, but I'm going to point it out anyway, just because I read the best running store stories thread on LetsRun. GPS watches only work outside. They will not be able to receive the satellite's signal on an indoor track, and they certainly will not work on a treadmill, since not only are you inside where the signal can't reach you, but your location is not actually changing. However, you can purchase an optional foot pod, sold separately, for indoor use.

The Garmin Forerunner 405 retails for $249.99 for the non-heart rate version and $299.99 for the version with the heart rate monitor. It is available from Garmin's website, as well as many running stores, including The National Running Center. The new Garmin Forerunner 410 retails for $324.99 for the non-heart rate version and $374.99 for the version with the heart rate monitor. The 410 is also available from Garmin's website and from many running stores.

Full disclosure: I bought this myself, and I'm pretty sure I paid full price, so nothing to disclose here.