Posted by: Ian | June 11, 2013

Sweden: Avoiding getting lost with a Garmin 800/810

Yesterday I had an ideal easy day’s cycling. After threading my way out of Motala, much of my route followed a bucolic minor road past lakes and meadows. Here’s a snap showing one of the roads that I took as well as one of the gravel tracks that I largely managed to avoid:

Keep left!

At the end of this post I have some recommendations on how to avoid letting your Garmin send you all over the place.

I arrived yesterday in Orebro, which is an attractive town, and had a fast ride today to Vasteras, which is another. Both are chock-full of people scooting along on Dutch-style bikes through streets, often cobbled, that favour cyclists and pedestrians far more than cars, buses or cabs. The civic architecture is very appealing and features stunning castles, cathedrals and churches set in a lacework of waterways. I’m spoilt for choice on which to show; here’s Orebro castle:

Orebro at night

Along the way, I’ve passed through some very quaint little places. These also have a very pleasing vernacular architecture; here’s a churchyard I passed this morning set in a small town in the middle of nowhere:

M.O.N.

A non-cycling highlight of my trip was an excursion around the Motala area that the owners of my guesthouse took me on the evening after the Halvvattern. This could easily justify a blog entry on its own.

Anyhow, as advertised…

Notes on route planning with a Garmin 800/810

The fundamental problem – and it is a problem – is an issue that I’ve written about before: the pernicious difference between a Course and a Route. You get a course when you upload a TCX (or, if you must, a GPX) file to your device. This does the following, once you load it:

1. It draws the course, using the points supplied in the TCX file and defined by your mapping software, on the map on the device.
2. It loads the cues, but only Left/Right/Straight, from the file, together with their coordinates.
3. So long as you stay on the course, it presents these cues to you as you get to the relevant points.
4. It calculates distance and time to the next cue, so long as you are on the course, and distance/time to destination.
5. It warns you if you go off course.

In contrast, a route is calculated on the device at ride time. Then:

1. It draws the route on your map. Whereas a course is shown in red, a route is shown in pink.
2. It gives you turn by turn directions for following the route (not the course), if you select this.
3. It gives distance/time to the next turn on the route on a different page to the similar course info. And it gives you time/distance estimates to your destination.
4. If you go off the route it recalculates another route, if you select this, either automatically or when prompted.

Thus whenever you follow a course you are getting schizoid directions and map pictures from both the course and the route. You cannot tell the device to navigate to the course!! Often, even usually, the two are coincident. However, they do differ and when this happens if you don’t pay attention you will be navigated off your planned course. If you want to stick to your course you cannot trust those turn by turn directions, for example. This is a really big deal if you are in an unknown land and do not have infinite time and/or fitness!

Forewarned is forearmed. I use this schizoid behaviour to give me options. For example, when wending my way around towns I may choose to use the Garmin’s ride-time route calculation over the one I came up with in BikeRouteToaster or RideWithGPS. But at all times I try to be aware of whether/how any divergence is occurring. My main methods for this are:

A. Look out for an Off Course warning. Once you leave a course you get no course info unless and until you rejoin it.
B. Look at the map page to see whether the red and the pink lines peel apart, and, if so, where they reconverge.
C. Look at the Time to Next field for the route and check that it’s decreasing – if not, you’re heading off the last calculated route.
D. Ditto time to the next cue point for the course, which is more serious (see A).

In general, I try to stick to *the course* by using these techniques. This is because I set the course in advance and know it to be reasonable. The route is sometimes (though quite rarely) nuts and it often adds extra distance.

A couple more notes:

1. Sometimes the Garmin says Off Course when it isn’t and you just need to ride on a little way for the Course Found message to appear.
2. When the route is having a conniption it can simply show a zero for Time to Next or some apparently random large number – recently I’ve seen a lot of values of about 4,000 miles, which, by coincidence, is around the radius of the Earth.

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