[LBCwanabe]

I'm asking because i lost one when i was on a ride the other day. I know they are not too expensive, but i don't want to purchase one if i don't need to. Thanks! Russell

 

[Prophet Julio]

if your talking about the little tension thing that "clicks " as you dial, then yes it is important because without it your barrel adjuster will turn and change the position of your derailleur or brake cable. Not a killer thing, but ghost shifting sucks, and brakes getting loose are a pain.

I used tape on mine until I had to get a new cable. The clip isn't so important , but holding position is.

 

[El_Duderino]

Are you talking about the little metal clip that holds the spring tension.
they are there to hold the assembly together before install, not meant to remain once installed
This one is tough to see in the picture but if thats what you are talking about you dont need it.