I wanted to first show you how this inertial valve works on the Fox, Fork. I am pushing on this fork as hard as I can, and it moves in some, but very slowly. But I can't push, push, push, push, and it gets to a certain point and nothing happen.
However, if I impact a bump from the bottom then it moves very freely ,until than it tightens up once that brass mass is moved down, that's the inertial valve movement. Now to check sag, I'll slide my zip tie down against the dust wiper, and now I get on to the seat very carefully, and you have to sit on the fork at least 30 seconds. Now ideally, what I would have here, is a weight I can beyond have my feet on the pedals, and my hands on the bars, and just may be have my elbow leaning against the wall. And I measure the amount that my rear shock is moved, and the amount my front shock is moved. My front has moved 12 millimeters up from where it was, actually 11 millimeters. So this is a 100mm fork, so 11 out of a 100 is 11%.
Ideally what you want is 15-25 % of the fork's length will be taken up in the static sag. So just based on the sag, you would say, well, you should let some pressure out of this fork, and I will show you how to do that. Put your pump on there. Once the pump screws on enough that it compresses the schrader valve, compresses the schrader valve, it will register on here. So this says 80 psi, but the air that was in that fork had to fill all this length, and bring it up to the same pressure in order to show this. So obviously that reading is not the same pressure that was in there before I put this on, so you have to figure that it's usually 10 -- you lose 10 psi, so I probably have this at 91 psi pressure. Pumping, this is how you increase.
Now I think I was at 91, and I didn't have enough sag, so I am going to drop by 5, about 85 psi, and now I am going to see what happens to my sag, and I can just leave the pump on there. Once again I am going to get up here really carefully, I am going to step up on this in riding position, and I check my sag again, and now it will be on 12 millimeters. 85 psi isn't a cut for me, so I am going to let some more out, that is just about 80, and I will slide this back down. I am now at 15 millimeters, so that 15%, that's the bottom end of the adjustment for a sag, and then I am going to remove the short pump, and you see how that didn't let any air out of the fork, it already left the schrader valve seal before the seal was broken on the pump.
When you ride, you can leave that on there if you want, but you can see a little bit of oil right there. As you ride, there is always a little bit of oil that comes out of the dust wiper, and you can usually see what your maximum travel was. The other thing you are interested in is maximum travel if you, at some point on the course, if you ride on a fairly rough course, you won't be able to use your full travel, there is no sense having all that travel if you are not going to use it.
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