Valve caps I keep on. I don't know why I just do. I took the wheel reflectors off my current road bike because they were the largest ugliest things I've ever seen. Dork disk gets removed for the already stated reasons.

I think there is a potential market, if someone has already come up with this idea, for a carbon fiber dork disk. Just rename it the aero spoke protection system and claim it increases aerodynamic efficiency by .002%.