The reason the safety police are so intent upon lock rings is so the torque of back pressure doesn't unscrew the ring from the hub and cause an unpleasant accident. There are a couple of ways around this, Locktite, using a bb ring to snug up against the cog (if you have enough threads), or run a rear brake. I use both of my brakes on my Twenty and have run a regular single sided bmx hub for 4 years. Never had an issue. If I relied on back pressure for all my braking, I'd probably set things up differently.