Your roadmap isn't only a guide but at times can be your best friend. Riding without it is like being lost in the woods after dark.
Let me give you some tips on how to reinforce your map so it won't fall apart after intensive use.
If you use a mapcase, reinforcement is a must. Folding, twisting and adjusting your map will most likely damage folds and outer edges.
Without any reinforcement, typical wear and tear (i.e. on bicycle rides) - will leave your companion looking like a ragged piece of paper.
Ready ? All you need is some strong, wide scotch tape! A tape dispenser can be a great time-saver :)

The most fragile parts of the map are corners, outer edges, folds and fold lines. These are the areas that require special protection against rubbing, folding and moisture.

Check the map for creases beforehand. All creases along the folds must be eliminated (ever tried to iron the map ? :) ) otherwise you'll leave undesired effects.:).
Apply the scotch tape against the map surface along the fold lines and edges carefully. Make sure the middle of the tape is aligned with the middle of each fold line.
All fold lines should be reinforced with the tape on both sides of the map.

After the tape is firmly stuck to the surface and the creases are gone, it's time to refold the map. Fold it slowly and gently along its original fold lines.
Thats it! :-)