Thats a good idea...apparently...you can just do this up thumb tight, with no ill effect...however, some people like to really lean on it...and ferk up teh head, so they cany get it out...this wont happen with a Karma....it does not need to be tight.
There are adjustable ones as well, Hybrid for example...only buy one if you like the look of it, and teh ability to remove it without tools, as teh adjustable side of it, is NOT required, and will only give you grief if you do...I have one, that said.