I don't know about the other way around but I'm using a Sram flat top 12 speed chain on 11 speed shimano and it's been ok
@PhilDAS 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.
I don't know about the other way around but I'm using a Sram flat top 12 speed chain on 11 speed shimano and it's been ok