Using a Garmin Edge 705 with OpenStreetMap for a cheap bike computer

Now that I am cycling in London a bit more regularly, and on roads with which I’m less familiar, I was looking around for a system for turn-by-turn navigation, and which, ideally:

I haven’t found a solution which hits all of these.

I had a look around for Free software solutions and, while there are some impressive self-builds available, all were more expensive than I wanted, and all looked a bit more fragile than I’d have liked.


OsmAnd is software which runs on an Android phone.

Although I don’t want a solution which depends on my phone, having it as a backup option is useful and, if I couldn’t find something which met more of my needs, I was not averse to getting a cheap Android device solely for this purpose. So it was worth a look.

I was impressed. I downloaded about 2GB of mapping for it (“just in case”), and then planned a few routes where I already had a reasonable idea of what would be a sensible cycle route and, more importantly, what would not.

Each time, the routing was roughly what I’d have picked already, and in a couple of cases it showed me routes which were probably better than those I knew from just exploring / riding around.

It will not be my main option, as I don’t want to use my phone for this purpose, but it’s definitely a viable backup for me.

Garmin Edge 705 and OpenStreetMap

A kind person on Twitter suggested that the now rather aged Garmin Edge 705 was still a good device, and that it is easy to load with up to date OpenStreetMap data.

For just under £50 on eBay, I found a second-hand unit with everything other than a heart rate sensor, which isn’t something I wanted anyway. The price was about right, and, since it was an actual bike computer, it should hit the various other requirements about not falling apart or getting damaged when used as a bike computer. Basically, it hit all my criteria other than:

So, some compromises, but acceptable to me.

Downloading routable OSM mapping

Since I want to use it for turn-by-turn navigation, I needed routable mapping.

OSM wiki has a page dedicated to Garmin devices and OSM, and a list of maps one can download.

I used the BBBike Extract Service, and a map of the entirety of the UK (way, way more than I need) was just under 1GB.

It does require you to hand over an email address, and there is no GDPR-compliant privacy notice, but I accepted the compromise and used a unique email address anyway. So far, I have only noticed that it has been used to send me one single email, to tell me that the mapping extract was ready for download.

Loading the map extract onto the device

Lots of instructions

FAT32 SD card mkdir Garmin/ Copy the .img file as filename.img Reboot the device

Very easy, and now I have up to date mapping.


Adding a route on a device with a touchscreen would be considerably easier, I imagine.

Creating a route on my computer, and side loading it works well, for when I know where I am going. I’ve got some pre-loaded .gpx routes on it - basically, different routes to and from Paddington station. I tested it a bit, and it’s going to get some getting used to, depending on whether I want turn-by-turn instructions, or the on-screen map. But, yes, happy days, I can now try to find my way to, say, King’s Cross using the back streets.

If agree to meet a friend somewhere, and I want to generate a safe route on the fly, that’s trickier. Doing it on the device, within a small geographic area, is fine. Not brilliant, not terrible. Fine.

In use while cycling

There is very little spare room on my Brompton’s handlebars, so it is perched very close to the my left hand grip. And, so far, it has stayed put, and it’s visible, so all good.

It’s been… fine! Basically, I feel like I’ve got my money’s worth.

Is it stellar? Nope.

But it does the job, and means that I don’t have to strap my phone to the handlebars, or rely on audio instructions.

It’s not as if I cycle miles and miles, or cycle every day (or even every week, really)

Will I stick with it?

I don’t know, to be honest.

It’s another device to charge, using a cable I don’t typically carry (mini USB).

It’s fun to see the speed I’m doing, and how many kilometres I’ve been, so I like it from that point of view.

But it has not - yet, anyway - been as revolutionary for me as GPS in the car was. That was a complete gamechanger for me, whereas this has been fine. As I cycle in London more (and I do have a few trips coming up), perhaps I’ll feel differently about it after those.

If it means I can get from A to B more safely, without having to put my phone on the handlebars, then I think that’s probably good enough.