Topforms

I'm confused.

See the following 4 images on imgur: http://imgur.com/a/iEYgI

• Big-Big jams the chain (scary)

• Small-Small and the chain comes off

• Small-Big is ok, and i actually ride this bike.

• Am I missing a spring on the derailleur?

I'm confused. I feel like the chain is both too long, and too short. It has biopace chain rings on, but it shouldn't really make so many problems.

I sorta think the derailleur is broken, or missing a spring. I doesn't really engage - see small-small. Is it missing a spring or something?

I'm considering just buying a new derailleur. But the chain-length issue i think will still be there? Any thoughts?