M970 or M971
 

How do i know which one i will need, one is a rapid rise and the other isnt? any help on finding out which one i need? many thanks!!

edit: sorry this is for a rear mech on my kona cindercone!

Shimano's rapid rise rear deraillers move in the reverse direction as traditional deraillers when cable is pulled. So while a normal rear derailler shifts to a larger cog (easier gear to pedal) when cable is pulled, a rapid rise derailer shifts into a smaller cog when cable is pulled. However, the amount of cable-pull per cog is the same, so it doesn't matter whether you use a rapid-rise or traditional-pull Shimano derailler for your bike. Your shifter will work with either one.

Not to be rude, but if you read up on what rapid rise is your question will answer itself. If it's a replacement, just find out what the old one is. If you understand how rapid rise works, it's pretty easy to tell just by playing with the RD (though they usually say it right on them). If you're building a new bike, well, do you want to run rapid rise or not?

Edit, just saw you have a pic of the bike in your sig. Like Tim said, yank on the cable there at the seat stay. If the RD wants to move toward the wheel, that's a regular RD. If it wants to move out, that's rapid rise.

Not that it really matters but which shifters do you have?

thanks guys i was reading on the shimano website about the GS and SGS version saying the GS only goes up to 32 teeth were as ther SGS goes to 42 or somthing.

i have deore shifters..

thanks tim. will check that tomorrow! cant wait for a new XTR rear mech... they look soooo sweet. might get the new xtr shifter as well. just to make the performance even better!

I meant how old are your shifters?

they are the 2006 model