Using GPS with Bicycling

by Dan Edgerton

bicycle chain

Over the years I have ridden to many different places on my bicycle, and quite often I have ended up getting lost. I have been lost in some very unusual places too. Once I was on a dirt road that disappeared into the James River as if the road was a boat ramp, even though the map showed that it went across. Probably long ago the road had been served by a ferry and it had never been removed from the map after it had closed.

Usually I don't have trouble when I ride locally since I have been riding these roads for years. It is when I head out to new places on a bike tour is when I have the most difficulty. In the past I would arm myself with maps and cue sheets which would bulge from my rear pockets and blow in the wind while I held them with one hand while holding the bars with the other. There was always anxiety about trying to find the correct turn. Confidence in the maps is never reinforced when you realize that the signs have different road names than the ones you have on your sheets.

With all this dissatisfaction concerning navigation I was pleased to receive a Garmin GPS 12 receiver and the optional handlebar mount for Christmas 1998. A GPS receiver calculates its latitude and longitude position from satellite signals broadcast by the Department of Defense. This in itself is not very useful unless you have a good map with you.

The GPS becomes more useful to bicycle navigation by using some of the additional features built into the unit. It is able to store 500 positions as "waypoints" and a series of 30 waypoints as a "route". By storing the positions of turns on a ride as waypoints on a route the unit will navigate you from turn to turn.

When navigating a route the unit will give you a bearing and a distance to the next turn. The GPS will determine the direction of travel when it is moving on the bicycle and will display the bearing as an arrow on the display. The majority of the time the arrow will point in the direction of travel with the distance counting down toward zero as you get closer to the next turn.

As you approach the turn the distance will reduce until it is almost 0. The unit will then decide that it has arrived at the turn and will update the bearing and distance toward the next waypoint. When this works properly the arrow will turn to the right or left as you approach your turn. When it doesn't go well you will find yourself stopped at a T intersection with the unit telling you to go 0.03 miles straight ahead. At least you know you are at the turn but you might need to check the cue sheet.

Obtaining the positions of the turns and managing the routes is best done with a computer, and at this point I must tell you that I use a Macintosh so how I do this will not apply directly to those using PC's. The part that will apply is that GPS is still on the cutting edge as far as practical real world applications so commercial software is hard to find and shareware applications are the norm.

DeLorme Street Atlas allows me to obtain the positions of the intersections on my route. I designate the start of my route with each turn stored as a stop. The end of the route is designated as the finish. The program will build a cue sheet while I make these selections with each stop's position listed with it. However, I have not found the DeLorme program to be useful for downloading the route to the GPS unit.

To move the route over to the GPS unit I use a shareware program for the Macintosh called GPSy, available from GPSy works with saved routes in the form of a text file so that you can edit them easier than you can with the DeLorme software. I simply copy and paste my route from the DeLorme program to a text editor. 

Each waypoint stored in the GPS unit must have a unique six character name. I will edit the names of the waypoints at this time to give them a name in the proper form and also add a header to the top of the file so that the GPSy program will know what type of data it is looking at. To load the route into the GPS is simple to do by selecting the text file from within the

GPSy program. Routes and waypoints are easy to manage between the computer and the GPS either by using text files or a database program.

There are many internet web pages concerning GPS and I would recommend the GPSy site as an excellent starting point. It has an extensive list of links to many GPS web pages that provide solutions for PC's, Palm Pilots, and Macs. Many of the best solutions are shareware solutions provided by people who are interested in using GPS units in their activities.

I have found mine to be very helpful in following routes I have made in unknown areas. I find that I consult my maps and cue sheets less often while riding and feel reassured when road markings do not correspond to map markings. If I deviate from the route it is easy to navigate back to it since the GPS gives you a bearing back to the route. It may be a useful tool you wish to investigate as well.

Page maintained by Tom Sheffield and last revised on Monday, February 20, 2000.
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