Check your chain line. Put the chain on the big chainwheel, smallest cog. From the back of the bike, look stright down the chain. Close one eye and slowly move your head back and forth until the small chainring is as thin as you can get it, now look at which cog it is lined up with, it should be no. 4 starting from the largest cog. If its lined up with 2 or 3, you need to move your chain line out.
Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1