I returned a couple of days ago from a week long mountain biking vacation at Lake Tahoe and Downieville, California. I had wanted to ride many of these trails for years and since I had not ridden them before, prior to going I downloaded tracks that others had posted online. Most of them came from MotionBased, although I did get a file of the Tahoe Rim Trail from National Geographic TOPO!'s mapXchange. Tracks from the latter are much easier to use now (even for non-TOPO owners), thanks to the newly minted ability of GPSBabel to convert .tpo track files from TOPO!
So I layered the downloaded tracks and waypoints on maps I then printed with TOPO!, constructed routes, transferred maps and tracks to my GPS, etc. But once on the trail, I was reminded what a useful tool these pre-loaded tracks are for navigation, especially when you are moving fast on a bike. The image at the left is one such track. Notice that I set the track color to blue.
The screen image to the right gives you an idea what this looks like in the field, as my actual track (in red) overlays the pre-loaded track as I progress along the trail. (These are reconstructed images, so the current position cursor is missing; I did not take my laptop on the ride to do screen captures!) With this sort of setup, it's easy to see at a glance if you've taken a wrong turn.
Now I do have a few caveats:
- This is no substitute for conventional navigation.
- The downloaded tracks are representations of someone else's experience, and may include a wildly inaccurate track, wrong turns, etc.
- Check to be sure that the downloaded track matches up to written trail descriptions and maps of the route that you are planning to take.
For example, in MotionBased, I chose the TrailNetwork tab, selected Quick Filters and added Hole in the Ground as a keyword filter, deleting the default "Last day" filter. Seeing a number of results, I noted that the trail I wanted used Truckee, California as the location. So I then used the Advanced Filter to construct a query for "location contains Truckee." Now I'm looking at the screen pictured at left. The description from Mountain Bike! Northern California says that the full loop is 16.6 miles, so I download the one with the closest mileage. Often I will download several tracks, which is very helpful when there are multiple route options. I download the tracks in .gpx format and open them in TopoFusion to check them out. If your GPS limits your saved tracks to ones with 250 track points, TopoFusion also has a nice simplify track function to whittle them down to size.
This is just one of many cool ways to use your GPS for trip planning and out in the field.