Anyone can sign up to edit OpenStreetMap. Once you’re there, navigate the map to the area you want to fix, zoom in, and click Edit. You’ll be given a walkthrough tutorial showing you how it works.

There are two crucial rules to remember:

• All edits must be factual, not opinionated. “Bikes are allowed along here” is a fact. “The surface is rough gravel” is a fact. But “I don’t think this is suitable for bikes” is an opinion.
• Don’t copy from other maps – whether Google Maps, Ordnance Survey, or whatever.

How cycle.travel interprets OSM data

OSM data can be ambiguous at times. cycle.travel deliberately interprets it cautiously, to minimise the risk of sending you on an unsuitable track. Here are some tips to get the best from your edits.

(A “tag” is the way you describe something in OSM. It has two parts, so highway=secondary means ‘this is a secondary road’. If you’re using the map editor on the OpenStreetMap website, you will set these tags with menus and checkboxes.)

• Always add a surface tag to paths and tracks, so cycle.travel knows whether it’s paved or unpaved, smooth or rough.
• If a path or trail is built to cyclable standards, tag it as a cycleway (highway=cycleway), not a path (highway=path).
• If you’re mapping something as a path (highway=path), a track (highway=track), or a service road (highway=service), make sure to expressly tag it as ‘bicycles allowed’ (bicycle=yes) – assuming, of course, that they are! Otherwise a track might be private, or a path might be for pedestrians only.
• In the rural US, limitations of OpenStreetMap data mean that many unpaved roads are currently missing a tag to say that they’re unpaved. cycle.travel is deliberately cautious in these areas. Adding surface tags to minor roads in the rural US is always useful.

If you’re a novice, be careful making widespread changes in OSM. The project has been running for 20 years, and if you find something that you think is systematically wrong, it’s just as possible there’s a less-than-obvious nuance that you haven’t noticed. You can ask for advice on the OpenStreetMap help forum.