Using a GPS to track mountain bike trails

The GPS tracks of the mountain biking trails on this website were made using a Garmin eTrex Venture GPS unit.  I got mine at the local REI store, although they're available at Eastern Mountain Sports and many other places.  It has a higher-resolution display than the lower-priced eTrex models.  You can get a handlebar mount for it if you want to use it for navigation and are willing to expose it to the possibility of damage in a crash.  If your only interest is creating a track of your route, it may be safer to turn it on and fasten it safely in your backpack.  I've tracked several routes with the GPS in my CamelBak where I didn't want to take the chance of crashing and damaging the GPS.

This unit also allows connecting to a PC and comes with a cable for that connection.  Note that it's a 9-pin cable and required a serial connection on the PC.  Many new "legacy-free" PCs don't have serial ports and can't be used with this device.  In that case you have two choices - (a) add a serial port board to the computer or (b) purchase a serial USB adaptor and plug it into your USP port.   On a laptop, option (b) is the only one available.  I chose (a) and added a 2-port serial card (about $35) to my desktop PC.  

The eTrex will capture a track by default, unless you turn off tracking.  You can save a track by name from the Tracks menu option on the main menu.   You can also turn off the tracking on that menu.

Creating trail tracks on Google Earth

The images on the web pages come from two different software packages.  The feature maps come from Google Earth.  If you haven't downloaded this application, do it now - it's amazing.  It has detailed satellite photos of almost the entire earth with varying levels of resolution, and in some areas you can zoom down to such detail that you can almost recognize people.  Find it at http://earth.google.com.  You can't use the free version for GPS tracking, but if you spend $20 upgrading to the Plus version you'll find that the GPS functions on the Tools menu is enabled, which will let you download from the eTrex.  Just plug in the extrex cable, select Garmin as the GPS type, and let it go to work.  It will download all of your tracks and mark then on the map.  It will also add the track to your "Temporary Places", and you can them save them to the permanent My Places.  The track will show as a thin blue line on the map, so you can see where you've been.  In addition, any waypoints that you've created along the way will also appear on the map.  Note that it will download all of your tracks, so you'll see them in other areas of the Google Earth map.

Here's a sample of the track on a Google Earth page:

Click it for a larger image.

Also note that you can save a location in Google Earth to a .kmz file.  If you email that file or place it on a web page, another Google Earth user can double-click on it to load Google Earth and take it to the location that you specified in that file.  This way you can easily take others to the location of the ride.

Plotting elevation profiles

Another great tool is the ability to plot an elevation profile from a ride.  This will let you know (as if you didn't know already) where the hills are, how steep they are, and how much climbing and downhilling you've done on a ride.  To do this you need TopoUSA from Delorme.  It's about $50 for the east-coast version (I assume it's the same for a west-coast version) and $99 for the whole country.  This will let you download the tracks from your eTrex and plot them on an elevation map.  You can go to the Profile function of TopoUSA and plot the elevation profile of the ride.  This will show you the height of each hill, along with the total distance, grade, elevation, climb and descent of each ride.  

In the version that I'm using, the software asks you to specify the name of the track to download, which I dutifully did.  However, for the eTrex it appears that the software will download ALL tracks, regardless of what you specify.  This doesn't really cause a problem, but will explain why other tracks may show up on your maps.

Here's an example of an elevation profile of a ride at Middle Run, DE:

These tools make riding a lot more enjoyable once the ride has ended, since you can review where you were and see how much work you did climbing the hills.