air preload-increase pressure.
ALOX-On the simple air forks I have had, the only way to increase preload was to increase the initial air pressure.Of course, this decreased sag, but it was supposed to.
I have a Black elite-strictly coil spring- and it has a preload adj.If it didn't I could probably stick some washers in it to preload it.
If it has a coil spring,just get a stiffer spring kit like old fart says.
If it is all air, then you can usually find a stiffer damping kit-just as old fart suggests.
If you are a cheapskate, you can just get some much thicker fork oil.Find out what it takes normally and go up 10 points.Motorcycle fork oil will work fine.Dump the old fork oil,put in the thick stuff-instant increase in damping.
Adding air is free-putting in thicker fork oil is cheap.A spring kit and damper kit are nicer, of course.Luck,Charlie