Originally Posted by caloso
I thought of that but I'm not confident about putting on a fixed cog without a lockring, particularly if it's hilly.
I run fixed both sides.
As long as you have a brake and rely on the brake for slowing and stopping, a securely mounted cog will not spin off. You could do without a lockring. I've never had a problem with a cog loosening, even when applying back pedal pressure when scrubbing off speed.