Becky Marvell found that the following worked well - particularly because it rained!
I used A4 plastic zip lock bags to put the maps into and printed them double sided so at the end of each page I turned it over for the next.  I used bulldog clips to attach the maps to the handlebars on a piece of cardboard so I always had the maps handy and dry!  http://www.ebay.co.uk/itm/25-Grip-Seal-Self-Resealable-Poly-Bags-9-x-12-75-A4-/300506388859?pt=UK_Packaging_Materials&hash=item45f793997b#ht_500wt_969  "