Originally Posted by
Bill Kapaun
It "appears" to be a 6 speed free wheel.
Assuming the RDER was set to engage the largest cog "somewhat correctly", 5 shifts would result in the RDER being off by 2.5mm or 1/2 cog by the time it reached the last cog, assuming my Shimano Free wheel-Accushift premise.
It may be set up so that on the largest cog, it is slightly over shifted toward the spokes. That would result in "quiet" running for the 1st up shift or 2 and then increasing chain noise as it is shifted to the smaller cogs.
Just because the OP didn't report problems in the other gears doesn't mean they aren't happening.
It's up to the OP to clarify if ALL the other cogs run "perfectly" or if things get worse through out the gear range.
Anything might be possible, but spacing problems are progressive, so while it would skip badly on the 1's sprocket, it would also skip slightly on the 2nd.
This is a case of looking for horses, not zebras when you hear hoofbeats (in the USA). While people often mis-describe problems, you need to start by taking them st face value. If someone reports a problem affecting ONLY 1 sprocket, start by seeing what may be different about that 1 sprocket, and a theory consistent with that. Then, if there's no good theory that fits, you can move down to more complex theories.
Of course, it's possible that once the OP resolves this specific problem, he'll still find he has poor shifting due to incorrect spacing.