Sorry for your loss. Here's a really simple and inexpensive idea: Get a good sized custom-made decal at a sign shop made in bright colored "reflective 3M vinyl" (the same reflective tape material used on semi-trailers) and stick it at the lowest part of the garage door eve. The reflective decal would simply say: BIKE ???

Remember to stick the reflective decal to the lowest part of the garage "eve" (not the garage door itself), so the decal doesn't disappear when the garage door is raised with the garage door opener. Get the decal made in "reflective 3M vinyl"; so if you come home at night, your headlights will illuminate the reminder decal.