Your LBS presumably has an axle vise, I would pay them a visit. Alternatively, the two cogs are gonna undo in opposite directions so you could try some kind of akimbo chain whip action. But I would just ask the LBS.
@Smolders started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
Your LBS presumably has an axle vise, I would pay them a visit. Alternatively, the two cogs are gonna undo in opposite directions so you could try some kind of akimbo chain whip action. But I would just ask the LBS.