The main source of the route information is your road-book. The participants are getting it not much before the race, usually the afternoon/evening before the start and they are trying to memorize it. The road book is made in the format of “Tulip road-book”. It is a simple ball and arrow system to show the route. Below is an example.
The big numbers in the first column is the total distance. The small number is the distance between the points.
The second column is the Tulip diagram. On a very simple way it give instructions on which direction to go at points and often include other information such as dangers, speed limits or easy to recognize landmarks as navigational aid.
The third column has some text notes and the riders can make notes here too. Beside the notes the most important information there is the compass heading or CAP. It tells you which direction need to go. 0 is north, 90 is east, 180 is south, etc. In our example the GPS coordinates of the point is also displayed next to the compass heading (CAP). The road-book is coming in a form of a roll. The riders can load it into a road-book holder and operate it with the buttons on the left side of the handlebar. The road-book holder is (3) on the picture.
The rider can read out the actual compass heading (CAP) from the GPS unit (4). In contrast to our everyday GPS it does not have a map, only displays the compass heading (CAP). The function of the GPS on the rally is to confirm your compass heading and position not navigation. The navigation is the job of the rider.
Additional help is the GPS repeater (2) or separate compass heading (CAP) device. It can display the compass heading (CAP), odometer or speed.
The last instruments in the cockpit are the trip-meters (1) which can be operated with thumb switches on the right side of the handlebar. These can help to keep up with the distance information in the road-book.
On the 2016 Dakar Rally, the average stage length was roughly 620km. The riders need to get through the stage (which is mostly a cross-country, off-road track) as fast as possible (the average speed is well above 100 km/h) and in the mean time doing the navigation by reading and handling all 5 instruments constantly. Not paying attention to the compass heading, missing to reset the trip-meters, not rolling the road-book means taking time consuming detours or getting lost almost instantly.
When you are enjoying the rally championship on the TV next time and marvelling the speed and ease as the riders are flying through the stages, remember how many other things they need to pay attention and getting the navigation done properly. It is bloody difficult.