We’ve had plenty of background GPS information and you’ve got a satellite fix. Now what can your GPS do for you? Two parts to this, first we’ll look at the basics. Bear in mind that all the actual GPS system does is tell the receiver where it is and what time it is. Everything else that the box tells you is derived from that information, so these features are all functions of the receiver rather than inherent to GPS and may therefore vary.
It’s a Global Positioning System, so you’d expect a position and that’s what you get – any GPS receiver will tell you where you are on the planet. Most will tell you using the familiar OS grid reference, although notable exceptions include Garmin’s Edge 205 and 305 bike-specific units. They’ll tell you where you are, but only in lat/long.
GPS receivers are capable of keeping a record of your journey. On Garmin receivers the data is available through the Trip Computer screen, and on Magellan receivers the information is contained within the GPS Position page. The data collected for the Trip Computer is cumulative, and should be reset at the start of any new trip. The choice of which data is shown depends on individual models (and often user preference) but will include some or all of distance travelled, time taken, maximum speed, average speed, elevation, height gained, current gradient and others. Garmin’s Edge bike-specific units also have training options like heart rate, cadence and the like.
Most of this stuff can be had from regular bike computers too, but the GPS approach has certain advantages. Using satellites means you don’t have to have wheel magnets and sensors and wires, there’s no need to calibrate for wheel size and you can easily use them on several different bikes. Whether they’re more or less accurate is a debatable point – wheel-sensor computers often throw up random maximum speeds or stop working if you go too slowly, but GPS isn’t immune from glitches either.
As you’re moving along, your GPS can tell you the direction you’re going, and if you’ve told it that you want to reach a specific point then it’ll tell you the bearing to follow to get there and how far away it is. That’s not a wildly useful function on a bike, as you generally stick to some sort of trail. It can be handy on little-travelled moorland areas, though.
One of the best features of having a GPS is the ability to store a record of exactly where you’ve been. By logging your position every few seconds, the GPS provides a kind of digital breadcrumb trail. If you get lost or the weather goes off you can follow it back to safety, or if all goes well you can connect the unit to your PC at home and analyse your ride at your leisure. It works the other way, too – with suitable mapping software you can plan a ride on your PC and upload it to the GPS to follow.
A waypoint is simply a place whose position you wish to record. You can use waypoints to record points of interest, places you took photographs from, where the pub is, hard-to-find trailheads and so on. If you’re at something interesting, a couple of button pushes and the location is recorded to help you find it again next time. If your GPS connects to a PC, waypoints can be downloaded and uploaded too.