Derailleur terminology..

[binzer]

Hello folks. I'm planning on upgrading my rear derailleur and in the course of shopping around I've come across some confusing terminology. Such as: Top normal (traditional), Low normal, and Rapid Rise. I was wondering if anyone would be able to explain the differences. Thanks.

[Alex Ramon]

They have reversed spring systems:
Top Normal - A derailleur that shifts to a larger sprocket (easier gear) when you PUSH the thumb lever. Then the spring tension (when you pull the forefinger lever) brings the derailleur back down to a smaller sprocket.
Low Normal (aka Rapid Rise) - A derailleur that uses the spring tension to shift to a larger sprocket (easier gear) when you PULL the forefinger lever. This type allows you to shift to an easier gear a lot faster.

[binzer]

Thanks Alex. All the different descriptions had me scratching my head.