Newbie here again. I just had a new chain and cassette installed at my LBS. I just noticed when I had it on the stand that when in the small chain ring and the smallest cog the chain sags down and actually rest on the chain stay. I don't ride here so never noticed it riding. Could the LBS mechanic sized the chain too long? The new cassette is an 11-28. It replaced a 12-30. I don't know enough to know if that makes a difference. Thanks guys for sharing your knowledge.