You can do this in two ways depending on your preference:
- Split the route into smaller sections and offline each one of them
This is the simplest option for smaller routes say less than 50km
- Offline the approximate area through which the route is passing
This may be more effective for very large routes
- Study the route path so that you can remember the approximate locations through which the route passes. Keep the route open on the dashboard for reference.
- Go to Settings > Offline Maps and start offlining small sections of the area along the path of the route. Slight overlaps between the section may yield better results. - Figure 1
- There is no limit on how many sections you can offline this way.
- When you ride this long route, the maps from the offlined areas will load automatically.