eTrex10 maps hacked!

Garmins eTrex10 is the cheapest and simplest of the eTrex series. It has a black and white screen that I think is easier to see in daylight and has less clutter than it’s more expensive colour siblings, but it also has the obvious disadvantage of having practically zero internal memory – only 8MB – and no memory expansion options. So while you can upload waypoints or a route, and while it will record your tracks, it’s capacity to store a map is almost zero.

But there is a way.. If you really have to put maps on your eTrex10, then you need to download these ‘fenix’ compatible maps here.

UK & Ireland map is here too (just in case the other link is broken)

If the latest version of Basecamp is terrible (it is) you can download the more stable earlier 4.6.3 version for Mac here.

These minimalist maps are for a Garmin Fenix GPS watch, but with a little bit of tweaking they’ll work on your eTrex10. First, download and install them into basecamp, and insert an empty USB drive into your computer. Select a track or waypoint (any one will do) and choose to ‘send to device’. When the popup window appears, select the USB stick as your GPS device, and select the checkbox to ‘send maps with MapInstall when done’. Go ahead and export that track to the USB stick.

When the MapInstall window appears, make sure to select the ‘fenix’ map from the dropdown list and pick the tiles that you need. Depending on the area you need you may be able to load up 2 or 3 tiles together, but don’t go beyond 5MB total on the data counter at the bottom.

The export will be almost instantaneous and your mapfile will be saved to your USB, in the Garmin folder, as gmapsupp.img

Now plug your eTrex into the computer. Open it’s Garmin folder and delete the gmapbmap.img file (this is the eTrex factory global basemap which is shite) – Now change the name of the gmapsupp.img on the USB stick to gmapbmap.img and copy it into the Garmin folder of the eTrex.

This should fool the eTrex into displaying your chosen map instead of the terrible global basemap, and now your eTrex10 has maps!!!

Creating a route: You’d think this is easy, and it is, but there’s still a few small tips to make life easier. In the basecamp toolbar, the create a route button looks like the android ‘share’ symbol, and the draw a track button is two muddy footprints. The fastest and easiest way to draw a track, is to create a route.

The dropdown list in the toolbar shows your current map, and you’ve options there to change maps. Some maps are ‘routable’ and some aren’t. If you’re going from point A to point B and you start to create the route while having a ‘routable’ map selected, the route will automatically follow the road or trail to get you from A to B.

If you need to climb a wall, or take up a CAP heading across an open field or forest where there isn’t a route, the route creator might take you around the block and bring you the shortest distance from the nearest ‘routable point’ to your chosen location. This isn’t really useful, so undo that last click, and then in the dropdown map list, switch to a non-routable map. When you click the next points in your route, having selected a non-routable map, it will just draw a direct line from your last point to the mouse click. Once you’re back on a trail / track / road select a routable map again and let the computer follow the trails for you.


How to use the route: The etrex10 doesn’t really ‘navigate’ very well (at all) so once you’ve created a route in basecamp, you’ll need to convert the route into a track before uploading it to the etrex. Just right click on it and select “Create Track from Route”

When you’re happy with your track, send it to your device and then safely eject the etrex.

At the trailhead, turn on the etrex, select “Track Manager”, select your track, select “Show on Map”, and then “GO”.

This will highlight the track as a bold black line that you can follow. There will be no turn instructions and no reroutes, but if you can glance down now and then, and keep it at a low enough scale (80 – 120m or so) then you should have no problem seeing turns coming up. If you’re walking, or going at a slow pace, then obviously use a lower scale again. 120m is great for fast trail riding, 80m in more technical conditions.

Mounting to handlebars: I use the Garmin mount kit to attach the GPS to my handlebars. I bought these clips on Amazon for €15 or so, and they work really well.

When I initially mounted the etrex to my bike, the Garmin mount was cable-tied directly to the handlebars. I had no trouble with the plastic spine mount itself, but in tough terrain the vibrations can snap the cableties and you may lose or damage the GPS.

Once I mounted it onto the foam bar-pad it doubled up as a shock absorber and the etrex has been solid ever since. 50+ rides and it never once fell off, and hasn’t snapped a cable-tie either since using it on bar pads.

That’s pretty much it. If you have an etrex10 then I hope you found something here that helps you use it. If you find a better way to make it work, please let me know.

Here’s the etrex10 in action:


Note it doesn’t fall off in the crash at the end.

It’s mounted to the bar pad using this mount, but some stronger cableties ;o)


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