Take a branch of wood. A flexible one. Willow tree is perfect.

Tie it to the bike so that it goes parralel to the ground and sticks some 30 cm to the left (if you ride on the right side of the road). Tie a piece of red cloth to the end of the branch. Cars will give you room.


Other, less orthodox solutions are taking the lane, or using this before every ride:



Rinse, repeat...