There are few things more satisfying in having your derailleurs in whole transmission working perfectly as you ride chain running smoothly, noiselessly and shifting exactly and precisely. And if you are riding through technical single track, it's important to actually have that confidence because if you don't, if you are worried about, oh, I should shift now, but if I do it's going to skip. So you don't shift when you really ought to.
So having everything work properly is great and what we are going to work on now is how to adjust the Rear Derailleur. The critical feature, of course, is the return spring which makes the derailleur, when you release tension on the cable come back. Alignment of everything is critical so having this derailleur hanger be flat and exactly in same plain as the frame, consequently the cogs.
Now with nine cogs and narrow chain and it will be very difficult to do that and today it's really crisp shifting whether using grip shift with a click, click, click, that way or some kind of lever- shifter, trigger-shifter, having the chain drop with every click exactly to the cog that you want, is what it takes for you to be able to shift under any conditions and get the gear that you want.
The cable tension on a SRAM Derailleur is only adjustable up here at this end where the cable comes up to the shifter and the Barrel Adjuster is threaded, and as you turn it, if you turn it counterclockwise -- when I talk about clockwise and counterclockwise I am always going to be talking about looking from the end of the Barrel Adjuster. As you turn it counterclockwise, it pushes this housing out more which pulls more tension on the cable and effectively shortens the cable. It's going to pull the derailleur further up. On most standard type of derailleur system when you pull cable you force the derailleur to go inward, toward the wheel.
There are derailleurs now called Shimano Low Normal System where it works the other way. As I tighten this up, it's going to move that derailleur inward, it's going to be lined up something like a half step over and I am not touching that shifter now. It's just wanting to automatically shift up because I've thrown off the Cable Tension Adjustment and the derailleur is in too far, so it's putting side pressure on the chain rather than just letting it sit on this cog.
So now I am going to turn that same Barrel Adjuster that I just showed you, I am going to turn it clockwise and as I turn it, it gets quieter-and-quieter, keeping the chain in the middle chain ring because when you ride a mount bike very often, you want to be able to shift all the gears from the middle chain ring, so across the entire cog-set.
So each click, it should drop-down and then each click, it should move up very nice and smoothly. You will notice while you are riding that if it drops down quickly but when you are try and shift up, it's sluggish, then that means you need more cable tension, but that's all there is to Cable Tension Adjustment.
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