I have an older model Nishiki International 15 spd with Suntour ARX derailleurs (friction shifters). When pedalled hard (under acceleration, up hills, etc.) the chain would skip off. I replaced the chain, as it was somewhat worn, and it no longer skips off. The problem I have now, is that when in the second smallest cog (and large chainring) the rear derailleur "skips" constantly. Playing with the shifter doesn't seem to help at all, and it doesn't happen in any other gears (yet). This didn't hapen with the old chain, and it is quite annoying as I used that gear frequently. Looking at it while pedalling, it doesn't look like the chain is trying to shift, but the jockey wheels (?) seem to jump forward slightly. Anybody have any ideas as to what to do?