What is the "high low spring preload adjustment" dial/cap

[MThomas]

Just above where the muffler attached to the cat exit pipe there's a reservoir-looking "cap" labeled "high low spring preload adjustment" (I'd attach a pic but can't figure out how to do it on this forum).
I've noticed something similar on other bikes but no one knows what this is.
What is this for?

[windy]

It's no longer April Fools day ! It is fir adjusting spring preload on the shock. The center is for standard load high is heavier , low is lighter. If you weigh 97 lbs. and have no luggage or passengers set it on low ,if you weigh 250 lbs. have full bags(22lbs.) and a 110 lb. passenger set it on high .

[EasyBee]

For the front and aft shock absorber

For the spring preload adjustment

[MThomas]

I think I understand the high (heavy load) vs low (light load) adjustment in the back (above the cat) but still unsure what the soft/hard "riding style" in the front means, i.e. what kind of ride is soft and what kind of ride is hard?

[riceburner]

I think I understand the high (heavy load) vs low (light load) adjustment in the back (above the cat) but still unsure what the soft/hard "riding style" in the front means, i.e. what kind of ride is soft and what kind of ride is hard?

soft/hard would be the damping.

The screws on the shock body control damping - this is the size of the holes that the oil in the shock can pass through as the shock compresses and extends. The smaller (or fewer) the holes, the slower the shock can compress/extend.

The hand screw on the remote unit at the rear of the bike is for 'pre-loading'. The shock works best when it is by default in the middle of its movement range - you can adjust the preload on the 'coil-over' spring for different rider/luggage weights to ensure that the shock is working in the middle of it's movement range.

[CycleRob]

If any shock absorber has only one S---H adjuster screw it is always the rebound damping adjuster, that is, it regulates how quickly the shock and the Front/Rear wheel extends after being compressed. That characteristic determines, in something anybody can understand after experiencing a series of "washboard" bumps, is if your bike's wheels will follow the road surface on a very bumpy curve (Soft) -OR- (Hard) go off the road into the woods (or into the On-Coming Traffic!!) as the wheels respond slowly to the road surface, essentially hopping/skipping between the closely spaced bump peaks . . . instead of cornering with where the road goes!! What should be known is that the min--max limits of ALL these "adjusters" do not represent a range of OFF to Fully Open, which would be really dangerous. They only allow a narrower range of adjustment WITHIN usable, sane limits. That's why you will not be riding dangerously, only less optimal, if you erroneously use Max instead of Min on the rebound adjuster screws. That can also apply to the spring preload knob adjuster, and that adjustment can have the inexperienced believing that it is only there for just a passenger's additional weight.

Most stock shocks do not have a compression adjuster screw as that property can be crudely metered automatically by what can best be described as a spring loaded 2 washer pop-off valve. More expensive shocks/bikes will instead have a more sophisticated pyramid shaped stack of many very thin washers lifting and bending to progressively and more precisely meter the oil flow rate for every bump level magnitude. That would mean an ability to accurately respond against a very high pressure road force, like when you hit a speed-bump-tar-hump at a crazy unsafe speed -or- just a sheet of 3/4" plywood lying on the road. That assembly will tightly regulate small suspension compression movements thru the exposed fixed orifice, while still being able to fully open up the blow-off orifices for progressively maximum damping oil flow. Only more expensive performance shocks (and SportBikes) will also have a compression rate hydraulic adjuster screw to precisely compensate for different rider weights and racetrack conditions.

Track day riders and serious racers eventually discover that raw horsepower is not as important as a premium shocked properly set-up suspension. Ask those winners who they use and if they can at least make your bike less dangerous.