Mountain Biking - Tips on preload adjusting and 'sag' level on forks?

I was reading around and discovered you should have a certain 'sag' on your front fork when you sit on the bike? I have a XCR Suntour 100mm fork ( http://www.srsuntour-cycling.com/SID=si064eb8393c4f7ce855c6676d7f982a/index.php?screen=sh.detail&tnid=144 )... It has preload adjust and I've got a decent idea on how they work..

Is there any good advice on what range the sag should be in? I'm 145-150 pounds, and just ride xc, lots of trails with some downhills with rocks and rock gardens. I have a Giant Yukon, the fork came stock on it.. I plan on getting a better fork in the future but I'm going to wear this one out first.

I've seen some people say no sag and others 10-15mm and some a full inch. Is just just on preference or is there a level of sag that will allow you to use most of your suspension without bottoming out on the trails?

To some degree it's personal preference, but sag does serve a purpose; it gives your bike "negative" travel so the tires maintain contact with the ground better as the wheel rolls off small bumps, roots, etc. This gives you better control.

I think the general recommendation is to have about 25-35% of your total travel in sag. That's measured with just your weight on the bike, in your normal riding position. The easiest way to measure it is to put a zip tie on the leg, sit down, get off to check the zip tie position, then adjust.

And feel free to play around a little bit with it so you can get a feel for what works best for you.

Also I noticed that it has two red markers on the preload adjusters.. should those be pointing in opposite directions or exactly the same direction as when I bought the bike? When I first got the bike the knobs were turned like \ / or should they be like: | |, \ \, / /, - -

for xc and little else thrown in Id say adjust to about 10-20% sag( 10-20mm on your fork). this will give a little less plushness for the technical stuff for better quickness and less pedal bob on climbs since you arent a huge downhiller/ freerider.a little experimentation will help you fine tune exactly what will give you the best of both worlds, bump absorbsion and control without mushiness or bouncing off of rocks/roots instead of through them

I'm not sure on the red markers...are you talking about separate adjustment on each leg? I don't know...my Fox has preload adjust on one leg and rebound adjust on the other.

I strongly suspect it doesn't matter.

I was reading around and discovered you should have a certain 'sag' on your front fork when you sit on the bike? I have a XCR Suntour 100mm fork ( http://www.srsuntour-cycling.com/SID=si064eb8393c4f7ce855c6676d7f982a/index.php?screen=sh.detail&tnid=144 )... It has preload adjust and I've got a decent idea on how they work..

Is there any good advice on what range the sag should be in? I'm 145-150 pounds, and just ride xc, lots of trails with some downhills with rocks and rock gardens. I have a Giant Yukon, the fork came stock on it.. I plan on getting a better fork in the future but I'm going to wear this one out first.

I've seen some people say no sag and others 10-15mm and some a full inch. Is just just on preference or is there a level of sag that will allow you to use most of your suspension without bottoming out on the trails?

Honestly, I don't think turning those "preload" knobs will make you notice any difference in ride quality. That being said, I run about 20mm sag on my Marz Pro ETA via changing PSI in the fork leg's shrader valve. :beer: