Hello. I ride a late 80's Nishiki Prestige with a 42/52 Sugino crankset and a Sachs 7 speed freewheel (13-24). I got the bright idea to send away for a 36 tooth chainring from Nashbar so I could go up hills easier. The part is by Stronglight and fits perfectly on the crank. I thought what could be easier? However, there are two major problems. When the 36 ring is with the 19 cog in the rear, things are smooth. When I shift down to the 21, the chain starts intermittent chattering. When I engage the 24, it chatters continuously. It has something to do with the chainline and the way the chain is engaged by the teeth on the 36, but I can't figure out why. The second problem is one of chain slack when in any 36 gear higher than 19- the chain sags and slaps the chainstays. I could take out some links I suppose, but then this might mess up my 52 gear combinations? BTW, the chain is around 2 yrs old, a couple thousand miles on it. Geez, I messed this all up. Any advice appreciated.