The first time I thought I wanted a GPS was when I was stuck up on the Monks Trod in some God forsaken part of the Cambrian Mountains in Wales. I had severely lost my sense of humour, the weather was closing in and it was getting dark. It was at that part just after the river crossing and through the man eating bog and to the top of the hill where you can see the Claerwen Dam to the left and well….nothing but open bog stretching for miles in front.

Of course we had a map, of course we can read a map and we know at least 20 trail and trials bikes had come through here no more than an hour previously. But we were lost. We could not even find the tracks of the bikes in front of us. Two DRZ's and two knackered riders and we did not know how to go to get back to civilisation. I'd lost count of the number of ditches and bogs I had dragged my bike out of. To be honest we would still be there if we hadn't come across another group of riders. It took six of us with ropes to free my bike! The leader of that group (which included Damon Hill) was Nick Ashley. I couldn't believe that Trevor knew him from just a week previously when they competed in a Classic Car Rally in France together. Nick seemed to know his way around - which ruts to cross at right angles and where you could jump the ditches. The rain was lashing and the wind was howling and he gave us good advice. He said 'Don't try to go where we are going - you'll never get through on those heavy 4-strokes. This is the worst I've ever seen the Trod'. Good advice and I would have heeded it - if he had actually told us where his group was going. It turned out to be the same place as us - the pub at Pontrhydfendigaid!!

If I had had a flare with me I would have used it - sod getting through this - I would have feigned a broken leg and got the helicopter in. But anyway we are stood at a ruined building following the guide's directions - it said aim for a sheep trough on the horizon. 'Hmmm, can't see one' I said. No compass, no flare, just a self-destructing map getting wetter in the rain. Now what I would have given for a GPS…

Things have changed with that little box of tricks zip-tied to the cross bar. It does not make up for rider ability (of which I have none) but it does tell me where I am and where I am going. In fact if used cunningly you can appear to be the most competent in the group. You will find that people are happy to follow you. They don't have to think, they don't have to read a map and they don't have to follow a route. You end up being in front because it's easier for those behind even if they are ten times a better rider than you!

You know what it's like sometimes when you go to an area you don't know. You're happy to just follow the local guide and at the end of the day you say 'Superb, that was really great, but where did we actually go?' They may show you on the map but that still means nothing. With a GPS you can come home again and plug it into the PC. All day the GPS has been saving a very accurate track log of where you have been. You can upload this to the PC and check for yourself if your run leader really did stick to 100% legal lanes!!!

You need to be a bit careful with this facility - I know one person who was convicted for speeding with evidence from his own GPS. My own GPS now shows a maximum speed attained of 513mph, which is a bit ambitious even for a DRZ with high lift cams - I turned the GPS on whilst flying to Spain!

There are many and varied GPS receivers on the market and it is a real problem to decide which is the best one for trail riding. Ideally you want a largish screen that you can easily see on the move. Buttons on the front of the unit are a good idea so that you can toggle between screens on the move - and buttons that are large enough to use with a gloved hand. Probably most importantly you need something robust and waterproof. Several of the Garmin range have all of these features. Some have IPX7 ratings, which means that they can be submerged for 30 minutes to a depth of 1 metre. This is a handy feature when you hit a rock and bin it in the middle of a river crossing! A lot of GPS receivers were designed for the marine market and the features cross over nicely to the trail bike world.

But which GPS is best suited to dirt biking? A difficult question. Much as everything else in life, the more you spend the more you get. There are a few GPS systems on the market that are excellent for trail riding and some that are brilliant for car driving. For example the top of the range car system is the Garmin StreetPilot III. This has street level colour map display and automatic routing (much the same as Microsoft Autoroute) plus voice prompts at each turn you need to make. You can ask it to guide you to a specific address, pub, restaurant, petrol station, tourist attraction and loads more and it will guide you there with turn by turn voice prompts.

Unfortunately it is probably a bit too large to mount on a bike and more importantly does not have the level of detail required for trail riding i.e. footpath, bridleway, RUPP and BOAT level detail. To be honest no GPS on the market has...so we have to compromise. The solution is to use your GPS in conjunction with digital OS Landranger maps on CD ROM. This just brings the paper map into the 21st century and allows you to view the same legend, style and colour of 1:50,000 scale map that you are used to, on your PC screen. It's a bit like the way we used to pour over the paper maps with a highlighter pen to plan a route. Now we can create a route on the PC with a few clicks of a mouse, linking waypoints together. What's really good is that you can then print off the area of the map that you want onto A4 paper and bring this on to the trail with you. At the end of the day you can bin it rather than trying to sellotape a sodden Landranger paper map back together. You can also download the route to a GPS for you to follow on the trail. In addition there is no limit to the number of waypoints and routes you can save on the PC and these can be emailed to friends so that they can check the route before going out. The guidance is then on a 'as the crow flies' basis but as each GPS can save up to 50 waypoints and up to 50 of these routes, it is not a problem. You can easily incorporate junction turns on the tarmac between lanes.

Now we are down to what GPS would be a perfect combination of the two above processes. The perfect dual-purpose unit is the Garmin GPS V. This is small enough to be used on a bike or car dash. It has automatic routing to guide you there in the car and then also has manual navigation abilities to guide you on the green lanes - used in conjunction with Memory Maps digital maps. The GPS V has recently been upgraded to the GPS V Deluxe, which comes with street level mapping for all of Europe included in the price.

There are cheaper alternatives, which are good for green laning, such as the Garmin GPS76 - rugged, waterproof with enough memory to save up to 50 routes with up to 50 waypoints each. It has the buttons on the front, which are easy to use when on the move with a gloved hand. The Garmin eTrex Venture is good as well for trail riding but neither of these units will calculate on-road routes to a destination. They will navigate you there as the crow flies but don't account for a road that twists and turns. Let's face it, most do! They also don't have street level mapping capability - for that you need to go for the Garmin GPS 76MAP or eTrex Legend .

I don't rate Garmin handlebar mountings but my friend made up his own with a bit of aluminium or I tend to zip tie it to the crossbar pad. It can't actually be hardwired because it doesn't run on 12v - it is 3.5v but you can install a cigarette lighter and run it with that. That is much better than the batteries that tend to be affected by the bike's vibration. For trail bikes without a battery you can install a racing style gel battery to power the unit. For the true adventurer you can get solar panels that will recharge your remote battery on the move. There are very sturdy and light Touratech mounting brackets designed for the Dakar type rally bikes. They are designed for each specific GPS and although they are not cheap, they are superbly engineered.

GPS and satellite navigation in general is still in it's infancy at the moment but I can foresee that in few years time they will be standard equipment on most cars and bikes. In the meantime they are essentially a gadget but a gadget that is actually useful and saves you a lot of time. Let's be honest, a GPS allows you to get on with riding your bike without all those 'where are we???' stops and that can't be a bad thing.

The Tech Bit - How does GPS work?

The Global Positioning System is a constellation of satellites that orbit the earth twice a day, transmitting precise time and position (latitude, longitude and altitude) information. With a GPS receiver, users can determine their location anywhere on the Earth. Position and navigation information is vital to a broad range of professional and personal activities, including trail biking, hiking, hunting, camping, boating, surveying, aviation, national defence, vehicle tracking, navigation and more.
The complete system consists of 24 satellites orbiting about 12,000 miles above the Earth, and five ground stations to monitor and manage the satellite constellation. These satellites provide 24-hour-a-day coverage for both two-and three- dimensional positioning anywhere on Earth.
Development of the $10 billion GPS satellite navigation system was begun in the 1970s by the US Department of Defence, which continues to manage the system, to provide continuous, world-wide positioning and navigation data to US military forces around the globe. However, GPS has an even broader civilian, commercial application. To meet these needs, GPS offers two levels of service, one for civilian access and the second encrypted for exclusive military use. The GPS signals are available to an unlimited number of users simultaneously, and there is no charge for using the GPS Satellites either.
The basis of GPS technology is precise time and position information. Using atomic clocks and location data, each satellite continuously broadcasts the time and its position. A GPS receiver receives these signals, listening to three or more satellites at once, to determine the users position on earth.
By measuring the time interval between the transmission and the reception of a satellite signal, the GPS receiver calculates the user and each satellite. Using the distance measurements of at least three satellites in an algorithm computation, the GPS receiver arrives at an accurate position fix. Information must be received from three satellites in order to obtain two-dimensional fixes (latitude and longitude), and four satellites are required for three-dimensional positioning (latitude, longitude and altitude).
Under normal conditions, the GPS signal will provide a civilian user an accuracy of better than 15 metres (50 feet). However, using a technique called differential GPS (DGPS), the user can increase the overall accuracy of the GPS receiver to approximately 1-3 metres. With DGPS, one GPS receiver unit is placed in a known location and the position information from that receiver is used to calculate correction in the position data transmitted to other GPS receivers in the area. The resulting real-time accuracy is in the 10-foot range. Sub-metre accuracy can be obtained by using DGPS and post-processing calculations in static positioning.

© Michael Kenny, www.k2navigation.co.uk 01993 810910