Okay, so I was trying to fix my front derailer yesterday (READ: trying to make it work at all) and it busted.

I'm not sure how it busted, but it's now a very light paperweight.

It's a Suntour Spirit on a 10-Speed Capri Cordova (two in the front, five in the back).

I went online to take a look at the prices involved with replacing my now defunct derailer, and I noticed that there were all different sizes. My question is: How do I tell which one is right for my application? Where to I measure and how?