fred_jb
Registered user
Active suspension (I think) also can alter the spring rate. As you can't alter the rate of a spring, something else is being used in place of a spring. Semi-active adjusts damping rates only. I'm pretty sure the pre-load is not being adjusted all the time. It's possibly only done when stationery or travelling at very low speed. And pre-load doesn't alter the rate of a spring, anyway.
The ESA technical information for some earlier bikes (possibly K1200/1300) explains how there is a mechanism which allows the spring rate to be altered via compression of an internal rubber part, but I think after some discussion we came to the conclusion that this is no longer present on the current generation, which is a shame. The preload on the latest auto-leveling suspension is only altered once on the move and does not alter while stationary, as I have found out through experience when going from solo to two-up and vice-versa. You start off with the preload setting from the previous load, and it is not until you start riding that it changes the preload to suit the current load.
I think the ride height is monitored continually, but doubt it is changed frequently as this could upset the handling. For example just because you go through a dip or a fast corner and temporarily put a little more compression on the suspension you wouldn't want the ride height instantly altered as this would negate the suspension action, and in any case unlike the active damping adjustment, I wouldn't think the preload adjuster is quick enough to do this. I would think it probably just works out the average ride height over a period of time when the bike is in a stable attitude, and only adjusts occasionally when it works out that the relatively long term average suspension compression has significantly changed.
I still don't understand why it doesn't adjust while stationary to at least get you somewhere near the right setting before you set off, unless it is not strong enough, in which case it may be super clever and it designed to only make brief adjustments during those moments when the suspension becomes temporarily unloaded during rebound from a previous compression, where changing preload adjustment would probably be easier.
Fred