I regularly travel nationally and occasionally internationally to play roller derby. If my roller skates get lost in transit (it has happened to people I know) my entire trip is ruined, so I prefer to take them as carry-on. When I'm going through airport security however, it is hit and miss as to whether they let you take them through. It varies between airports and even security staff. One time a security officer asked their supervisor and they were cleared to go through, another time the supervisor said no.
Are roller skates specifically allowed through airport security as carry on? I'm interested in Australia, the UK, the USA and Spain right now, but more broadly continental Europe as I may be flying there sometime in the future.