Global positioning systems (GPS) are small satellite receivers that can pinpoint your location -- and often your elevation -- anywhere on earth. GPS mapping devices have become common in cars, but they're also starting to make their way onto the mountain biking trail. Mountain bike GPS systems are typically smaller than those in cars. They can be mounted on handlebars, slipped into a jacket pocket or even worn as a watch.
Mountain biking GPS systems are useful both as safety devices and training tools. In a pinch, they can help you find your way back home, but they also help serious riders track their ride times, average speed, overall climbs and more.
The track log function on a GPS device acts like a digital breadcrumb, recording your exact position during every second of your ride. This function can come in handy for several reasons.
If you veer off the trail, you can consult the log to find your way back to familiar ground. But you can also use the track log data to construct a detailed trail map that can be shared with other riders. Using special software, you can convert your log data into a file that can be uploaded to sites like Google Earth, where users can view your trail on an interactive map.
It works the other way as well. On sites like SingleTracks.com, you can search and download trail data as a GPX file. These files contain the precise GPS maps of an entire mountain biking trail, including how long it will take to finish, inclines and elevations, and more. You can load the trail map onto your GPS device and it will alert you to upcoming turns and let you know if you've wandered off the path.
Mountain biking GPS systems can also be paired with training software that helps professional riders slice seconds off their race time. Perhaps they're slowing down too much during turns or not accelerating enough on downhill stretches. The computer knows all.
Finally, let's take a look at the tools every well-prepared mountain biker should take on the trail.