Sunday, 2 September 2012

OpenStreetMap on your Garmin: OpenMtbMap

OpenStreetMap is a database full of really useful free mapping data. There are several views of the data, such as the Standard map and OpenCycleMap you may have seen on the web or via a phone app.

Some clever people have also converted the data for use on Garmin GPS devices.  There are an overwhelming number of maps which all look different.  The best map I have found for cyclists is OpenMtbMap. Screenshots are hard to come by so here are some running on a Dakota 20 ...

The overview map (see on OSM). Note the scale is 8km. The Dakota 20 struggles to redraw the map at this scale, taking around 5s to draw the map. It gets quicker if you zoom in.

Planning a route is too painful on such a small screen so I do that with a paper map or at home, saving a gpx track of a planned route and copying to the Garmin.

Zoomed in to 2km (OSM), the map data starts to come alive. The green, orange and yellow routes are standard roads, primary(A), secondary(B) and tertiary(C).

Solid black is an unclassified and paved road. Eg north from Rampton.

Other OSM-on-Garmin maps show some unpaved routes but not with any great detail, it is really hard to tell the difference between a smooth track and a muddy footpath.  OpenMtbMap does a better job. More in the next pictures.

Zoomed to 800m in near Rampton (OSM).

Red is a track of some variety. In the UK this does not mean a legal right of way. All of the tracks on this screen can be legally used.  The marking, solid or dashed is telling you something about the quality of the surface. Haven Drove G5 is a Grade5 track in OSM data on a scale of 1(smooth) to 5(bumpy and having a soft surface).

Brown and Grey (in the lower left quarter) is a bridleway. In the UK legal for bicycles to use but not motor vehicles and is an important distinction.

Dotted black is a footpath. In the lower right quarter there are a pair running either side of a drainage ditch (blue).

Very useful is the marking of the National Cycle Network (see on OpenCycleMap).  The thick black marking denotes a cycle route.

Note when selected with the pin, the name appears at the top. The menu reveals the full name "Ucl Ncn Natonal Route 51".

OpenMtbMap is of course aimed at mountain bikers.  It has a lot of special markup for hills and terrain used much more in Europe. Here in Cambridgeshire, it is an extremely flat part of the country but we have Thetford Forest locally with both marked an unmarked mountain bike trails. The screenshot area is on OSM and the OpenCycleMap layer. There is a lot of detail.  Working left to right:

 Green dashed is mtb:scale=1.  This is what I have marked as good singletrack for mountain biking. It is useful to distinguish from other paths that are either uninteresting or for walkers (appearing as solid dark red but not on the screenshot).

Thick orange is a B road.

The trail marked with a blue edge is a marked cycle route known as the Lime Burner Trail, with this small section named The Beast.

The three brown trails are all highway=path in OSM speak with subtle variation of surface.

The red dashed and straight sections are tracks. The whole forest is on a grid system and these are everywhere. The Fire Roads are wider and harder packed with many marked solid red in OpenMtbMap.

Road names also appear when clicked, such as Lack's Close (OSM). Also note the brown dashed footway which is a useful pedestrian route between houses in my village.

There is some useful data that can be searched.  In the screenshot it is displaying the points of interest in the Shopping menu. Not all shops are there, only the ones that are in OpenStreetMap but it is useful having positive information about the location of a shop when cycle touring.

Sadly, additional information such as phone numbers does not make it into the Garmin.

A few nuggets of information:

It is worth noting that postcodes are not generally in OSM data so you cannot navigate like you would with a car satnav.  Additionally, address searching by road name also does not work in my Garmin. The reason is because to get OSM into a Garmin format, the data format has been reverse engineered. I believe you can get this working if you upload the map via Garmin's MapSource software.  The work around is to find the road you want on the map, highlight it and navigate to it. Also, auto routing is very hard to do when you go off road, mostly because of the data. OpenStreetMap data is going to give you the best chance if you want to do that but you should be aware of the quirks of OpenMtbMap's routing.  One example is that it will not route you on Primary Roads (unless specially tagged). This is a good thing in my opinion but a quirk is that it prevents my Garmin routing my over this staggered junction. If you are a road or touring bike rider you probably don't want to install OpenMtbMap.  The same author has created VeloMap which should not route you over aggressive mountain biking routes.

I do not rely on autorouting. I prefer to follow a pre-planned gpx route.

You can get contours. I prefer without because they clutter the map.

If you want a plain map for just road use, the Talky Toaster OpenStreetMaps are very good. I switch to these if I need to use the Garmin Dakota on my motorcycle.  You can see offroad trails in the screenshots but you'll see they are all simple grey lines.

Installing OpenMtbMap on your Garmin: The way I install this is to download the UK build from OpenMtbMap, run an exe to build me an IMG file, plug in the Garmin via USB, and drag and drop the file onto the Garmin disk.

As a final note. Around Cambridge we are blessed with very good quality OSM data.  When I travel to other locations such as the Peak District I find lower quality map data. This is most often bridleway routes marked as footpaths, and occasionally missing routes entirely. My pattern is to plan the route (on BikeRouteToaster) using an OSM map view, falling back to Google Earth if unmapped, then save a gpx file of the planned route.  I follow that on the ride then upload the missing gpx data to OSM (you should not copy data from other map sources, this keeps OSM data free).


  1. I am thinking of moving to Cottenham and wanted to see what it is like to cycle into Cambridge and back as I would like my daughter to visit me and she only has a bike. Why do they allow the cars to go so fast on what looks like dangerously lit roads. I have been on these roads during the day but there is no way I would cycle on them at night. I would fear for my daughters safety. Is there any way we can get the speed limit down?

  2. Hi Midwife,

    Did you notice the cyclepath between Histon and Cottenham? Its actually pretty good and used by a lot of commuters and teenagers. It starts at the edge of Cottenham and you can cycle on it all the way to the lights at Histon Green. At night it has solar lights marking the edge (pictures here). Inside Cottenham's 30mph zone there is still an issue with speeding. Most women choose to remain on the (foot)path until the green where speeds are lower.

    The speed limit on the B1049 has been lowered to make it more pleasant to cycle. It is 40mph between the A14 and Impington which has made a huge difference. Between Histon and Cottenham it is 50mph now, but widely ignored. Its unpleasant, but won't cause any major problems unless your daughter wants to cross the road at the northern end of the cyclepath.

    Cottenham has quite a good bus service, but it is expensive - £5.70? return for adults, taking about 45 minutes to central Cambridge. It is popular with the young and old.

    Ultimately, it is quite a good place to live if you would spend much of your spare time within the village. But if you like to socialise in Cambridge all the time, you will spend a good chunk of time and money travelling.