Originally Posted by
davester
As noted above, SRAM bought Sedis so a new SRAM chain is the same thing as a Sedisport.
Current SRAM 7-8s chain is a copy of Shimano's first narrow chain ("UG NARROW") which was only subtly reinforced to produce their first HG chain.
I believe a patent expired around year 2001 which allowed SRAM and others to use Shimano's exact bulged sideplate design, and SRAM re-designed their 7-8s and 9s chains at that time. Better shifting resulted.
The Sedisport was I believe the first bushingless derailer chain. All of today's derailer chains are descended from that one feature, although they are also all much more flexible laterally than Sedisport chain.
Pre-index derailers (other than the Duopar and certain MTB designs) tend to struggle with maintaining constant chain gap, such that if a large 32t freewheel is used the gap is big when the small cogs are selected. But the more-rigid Sedisport can give shifting response on those derailers that is closer to the rigidity of earlier bushed derailer chains.
I sometimes use
7s Shimano SIS levers to work with vintage Suntour or Shimano non-indexed derailers and standard-spaced 5- or 6-speed freewheels, which indexes/works pretty darn well even using modern chain if the freewheel isn't so big as to cause big fluctuations in chain gap. The Sedisport chain or traditional bushed chain may actually help with shifts across the smallest cogs on such setups as compared to using a super-flexible modern chain.