For years I would stick the race tags on my seat post resulting in an unattractive build-up of vestigial adhesive.

Then I came across a brand named Vondrais which makes rigid plastic attachments that connect to the bottom of your saddle or your seat post upon which you can stick the race number.

A Vondrais race tag in action

They hold the number rigid, making them easier to see, and they prevent them from flapping in the wind, as the Vondrais is like a plastic card.

I like to think they save me a fraction of a watt, plus they look cool.

Buy one here: