Came across EventClip Pinless Number Fasteners the other day and promptly ordered a pack. They have just launched us a US website. I bought 4 packs and got 1 free, which was brave as I never used them before.
So it goes, my husband is now using them too for his cycling! You just punch a hole in your number and pop a clip on. They do what they say, don't make holes in your kit! Fab find, so I thought I'd share with you guys.