I have an old, but excellent condition Nishiki Ariel I purchased used. I had the bike checked out at the local bike shop who stated the chain and cassette were badly in need of a cleaning, but still in good condition. For reference in this discussion, the rear unit is a 7-speed Shimano Deore, all original and working fine. The bike is of 1989 vintage.
I needed a chain for another bike, so I decided to buy a new chain for the Nishiki. The bike shop sold me a SRAM PC-68 (for 8-speeds, but this should not be a problem). They recommended the SRAM and I like the SRAM with the powerlink. It is THEE cool chain to use in this area.
I removed and cleaned the cassette, re-installed it and installed the SRAM chain after matching the length to the old chain and lubricating it with Finish-Line Teflon Plus. I noticed an immediate improvement in shifting, but that was the last good news I had. As soon as I shifted to the top end gears and applied some power, the chain (or cassette) started skipping (or slipping). This is only a momentary skip or slip, like a one link skip, but it is a major concern. The higher the gear, the worse the problem. This only occurs when using the top three gears. I feared the worst, I might have damanged the cassette.
I cleaned the old chain, lubed it with teflon-plus, and installed it. The skipping stopped, completely stopped.
OK, does anyone have any idea what's happening? Do I need to adjust the deraileur with the new chain? Is the SRAM not compatible with the old Shimano cassettes? I did not remove the thin layer of packing grease from the new SRAM chain, is that a possible problem? Has any one else experienced this. Thanks for taking time to read this and respond.