To find out what stairs you can currently challenge someone in, first go to the Main Stairs Page, then click on "Show your stairs only" link. The ones in BOLD are ones you can make a challenge in. .
Czuch Chuckers: That is a good question. I remember suggesting if that happened, then first send user a warning to get out of some, then if they don't "randomly" put them into "retirement" in all but 1..... where if they do renew their membership at some point, they can start from where they left off from.
But I'm not sure what Fencer ever did or if something like that is in place.