Monday, June 13, 2011

Downloading Open Source Maps for Garmin Edge Computers

A not so widely advertised feature of the Garmin Edge cycling computers is the ability to use free maps from open sources. There are two main reasons why someone would want to this:
  • Garmin maps can be very expensive; or,
  • to get a map for an area not covered by Garmin maps.
An open source map downloaded this way will not natively provide for turn-by-turn navigation, though this function can easily be added by uploading a course (*.crs file) to the unit that has been pre-processed by Bike Route Toaster.

That said, for simple map navigation, these maps are great, free, and totally legit.

Here’s how to do it:

Select and Download the Map Area:

Download and install Mobile Atlas Creator (MobAC). Formerly known as TrekBuddy Atlas Creator, it is an open source (GPL) program which creates offline atlases for GPS handhelds and cell phone applications.

Install it (unzip it) and run it simply by clicking on the Mobile Atlas Creator.exe file (if you plan on using it a lot, just make a shortcut to this file on your Desktop). You’ll be presented with a screen that looks like this:

You can easily change the map area in view by zooming in and out with your mouse wheel. To move to the left and right simply move the mouse with the right mouse button pressed. You’ll note a scale for Zoom level in the upper left hand side of the map screen. Centre the screen on the area you would like to capture. 

Under map source in the margin on the left, you’ll see a drop down menu with various open map sources. Older versions of MobAC would let you view non-open-source maps, like those of Microsoft Maps and Google Maps, but these agencies required MobAC to remove these sources, and all that is available now are those maps from OpenStreetMap. This is fine for cycling actually, as I have found the best map for cycling is the OpenStreetMap Cyclemap. It shows off-road bike trails (including MTB trails), as well as elevation contours.

So, under the Map Source drop down menu, select OpenStreetMap Cyclemap. Under Zoom level, check only 14. Higher zoom levels do not work in the Edge devices, and lower zoom levels do not show up with enough detail. Note that unlike Google Maps on your Iphone or Android phone, which looks at distinct tiles on different levels when zooming in and out, Garmin devices let you look at one big picture map, and when you press + and – on the unit to zoom in and out, it just increases or decreases the magnification on that one big map, so it is critical that you use the right zoom level, and only one zoom level.

Now, give your map a name in the Name: box, and click on Add Selection. Your screen should look like this below: 

Then, simply click on Create atlas and your file will be created (*.kmz format) in the location specified.

Moving the kmz file to your unit then simply requires that you plug the Garmin unit in with USB cable, and transfer it to the right location, as follows:

Install the Custom Map on your Garmin Edge:

(Note, this procedure applies specifically to the Edge 800, but would be similar for the 705).

1. Plug your unit into your PC via the USB;

2. Open the directory for the SD card (assuming you have one, if you don’t, simply use the existing memory card in the unit, assuming there is enough space on it);

3. Create a directory inside the Garmin directory called CustomMaps (no space), so something like k:\Garmin\CustomMaps;

4. Move the .kmz file into it.

Then, disable the other maps in your Garmin 800

1. Unplug the unit from the PC and turn it on;

2. Go Menu > Settings (wrench icon) > System > Map > Select Information Map;

3. Click on the other maps and select Disable;

4. Click on the Custom Map HK_Territory (or whatever you've called it) and make sure it is Enabled.

That’s it!

The result should look like this when looking at the map page in the unit. Note the detailed contours and trails, and even the golf course area in grey, around the Discovery Bay district here in Hong Kong:


  1. My map isn't showing up on the Garmin??? Please help :)

  2. Make sure you only have one zoom level selected, and make sure it is zoom level 14. See para 5 under "Select and Download..." above.

  3. This was really useful to me, as I've just bought an edge 800. Is there a limit on the filesize? I created a kmz file using this method, and the garmin device suggested it was too large.

  4. Thank you for this... I just used it on my new 800 and it worked great!

  5. Damn, the map source you suggested has been removed and the others dont have enough detail at zoom level 14. The search continues...

  6. Thanks for that excellent step by step explanation... the funny thing is that I also live in Disco Bay!

    Actually, I sticked to your procedure, but the final output is terrible - like a very low-res jpeg pic. I lurked around with different settings, but still cannot find the way to get a decent output.

    I use OpenStreetMap Mapnik, since your Cyclemap is no more an option.

    Your insight would be much appreciated... thanks!

  7. Alan, yes, there is a file size limit. Can't find any reference to it in any Garmin documentation, but some files a simply too big to work.

    bussinit and Francois, yes, the good map sources have been removed! The CycleMap which I used at the time of writing this post was by far the best resource for cycling and hiking in most parts of the world. We can only sit and wait until someone has the kindness to give us access to another good one.

  8. Follow this to have again OSM cycle maps in MOBAC.

  9. Thanks @dentex!

  10. Hi dentex, thanks for referring one of my post here for the benefit of everyone.

    I own a Garmin eTrex 20 for my hiking trips and i am able to build my Garmin maps with topographic contour lines from OpenStreetMap.

    To get a routable street map, refer to

    If you need the topographic contour lines overlayed to the routable street map, refer to

    I am not sure the map works the same way for Garmin Edge like it worked for my Garmin eTrex 20 but never the less you can try it out.

  11. In case you've missed it, this procedure I describe above has been completely superseded by an automated process brought to you by the kind folks behind Open Street Maps. DC Rainmaker has documented how to download free open maps here:

  12. And this automated procedure can take 2-3 days to complete! So if you're still in need for a quick map, the above procedure is totally valid an quicker!!

  13. Trying to make this work for a while now. Following these steps, I eventually get a .kmz file with a size of only around 500 kB (area of the map is 100km by 50km), which corresponds with the very low resolution map my device shows. How do I obtain the detailed topographic map on my Garmin, or what did I do wrong?

    Nevertheless, thanks for this nice initiative

  14. Make sure you have only one zoom level selected, level 14. Also note that since I published this, DC Rainmaker has published a post on a more automated process here. It's the one I use now.

  15. Yes, I've already worked with that one. But it seems to me that maps with elevation contours aren't available (yet?)...

  16. One of the best post i have ever seen,
    .i really like it.
    Good work.

    specialized road bike