Actuation Ratio !

[atlantis]

Hi !
I own a Btwin forme 1 , the shifters are grip shifters Sram 3.0 comp and the rear derailleur is a Sram 3 (1:1 actuation ration)

I plan to change the grips to trigger, following are the options :

1> Saw this deal, but the actuation ration varies in both
http://cgi.ebay.com/NEW-SRAM-TRX-7-SPD-TRIGGER-SHIFTER-X4-Rear-Derailleur-/330568388747.
Is this compatible with each other?

2. Another deal can I use these triggers with my current setup
http://www.jensonusa.com/store/product/SL400A10-Sram+Trx+Trigger+Shifter+Set.aspx

If someone could explain the actuation ratios , i would be grateful.
thks

 

[doiturself]

Ya can't mix SRAM shifters with Shimano ders, or Shimano ders with SRAM shifters. However you CAN use SRAM and Shimano cassettes interchangeably with either a SRAM or Shimano shifting setup (that would be all Shimano or all SRAM with respect to both shifters and ders).