Thanks to Lexanne Creitz for showing me this solution many years ago....
I hate carrying my keys in my water bottle holder - I always worry that I forget to close the zipper on the pouch and my keys will end up buried if I crash. And I generally don't have any pockets with I race. And simply leave it in my clothing bag? I sometimes lose my ski boots in my clothing bag - keys would never be found
In the tradition of Gel on a string, the solution is put an extra key on a bright shoe lace and hang the shoe lace around your next, with the key hanging between your race suit and your long underwear. It's always there, easily reachable, never lost.
Car pooling? Make extra copies of your key. Put each on it's own brightly colored shoe string and hand them out to everyone in the car. The bright colors makes the keys hard to misplace.