Your chain looks rather slack, but still, massive slipping shouldn't happen. How's the chainline?
Chainline is perfect, so that shouldn't be the issue. I guess the rear cog is just worn, I'll replace it and we'll see.
@vpCogworks 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 chain looks rather slack, but still, massive slipping shouldn't happen. How's the chainline?