The supplies you'll need are cardboard pennants (you can make your own or buy them pre-made from a craft store), gel medium to use as glue, a brush for applying the gel medium, an X-Acto knife for cutting out your photos, and some string or twine for hanging the banner.
First, pick out the photos you want to use and print them out. Use a pennant to create a template to help you decide how you want to cut out the photos.
Put a coat of gel medium on your pennant and carefully mount the photo. Start by lining up the bottom point and then work up from there. Once it's dry, cut out the holes with an X-Acto knife.
Decide how you want the photos to be arranged and then string them up. I simply tied a couple of knots on the ends to hook around nails. Enjoy seeing and sharing your bike photos!