Does Dynamic ESA have variable Spring Rate

[BigKev67]

Does anyone know if the current dynamic ESA still has adjustable spring rate.
I know that the bike adjusts rear spring pre load each time you set off according to how far the rear shock is compressed - this will achieve optimal SAG.
What I am not sure about is SPRING RATE.
Some years ago My RT had a spring consisting of two elements, a conventional coil spring, and an elastomer contained within a sleeve. The ESA moved the sleeve to vary how the elastomer was restrained, and hence the stiffness of the elastomer varied creating a change to the overall spring rate.
What I dont know is whether this adjustable elastomer is still used in current ESA as its its not mentioned anywhere.

 

[yofi]

Does anyone know if the current dynamic ESA still has adjustable spring rate.
I know that the bike adjusts rear spring pre load each time you set off according to how far the rear shock is compressed - this will achieve optimal SAG.
What I am not sure about is SPRING RATE.
Some years ago My RT had a spring consisting of two elements, a conventional coil spring, and an elastomer contained within a sleeve. The ESA moved the sleeve to vary how the elastomer was restrained, and hence the stiffness of the elastomer varied creating a change to the overall spring rate.
What I dont know is whether this adjustable elastomer is still used in current ESA as its its not mentioned anywhere.

https://www.bmw-motorrad.co.uk/en/experience/engineering/detail/comfort-ergonomics/esa-esatwo.html

The bikes are still ESA ii, simply that they've changed the options for set fro solo etc to min, auto, max.

 

[Weird Bob]

I think the k1200r/s and 1300 r/S used that same setup.

That is no longer the case. I think there is a user on here (Denzo I think) who rebuilds suspension. He has posted a good few pictures of the suspension units disassembled to be rebuilt.

 

[tanneman]

Clever trick by the ESA which was introduced on the LC models I think.

Optimal sag can only be achieved with in the parameters of the design. Remember that.

 

[Boxerlust]

THE K1300 models had the elastomer too but on the latest ESA you pretty much have 3 settings...minimum compression of the spring,maximum and auto that keeps the bike at the optimum ride height no matter how fat the girl on the back is... I ordered some tractive shocks myself that are very expen$$$ive but the only ones that work with ESA and have supposedly faster responding valves with stiffer spring rates 55 F and 180 rear because for my taste the suspension is too soft setting on max and dynamic pro if you go fast...But these also have regular constant and not progressive springs that would get harder the more the shock travels towards the bottom.

 

[Weird Bob]

Ahh found the breakdown post

https://www.ukgser.com/forums/showthread.php/510100-SACHS-SHOCK-REBUILD

 

[BDG]

THE K1300 models had the elastomer too but on the latest ESA you pretty much have 3 settings...minimum compression of the spring,maximum and auto that keeps the bike at the optimum ride height no matter how fat the girl on the back is... I ordered some tractive shocks myself that are very expen$$$ive but the only ones that work with ESA and have supposedly faster responding valves with stiffer spring rates 55 F and 180 rear because for my taste the suspension is too soft setting on max and dynamic pro if you go fast...But these also have regular constant and not progressive springs that would get harder the more the shock travels towards the bottom.

The Tractive ESA shocks are great. Way better imho

 

[Myke Rocks]

Just a comment on spring rates.

Think of a spring as a torison bar which has been wound up in a spiral, because that is what it is.
If the bar is shortened, the spring rate increases. (Visualise by imagining it 100mm long, and then 1metre long.
On many bikes, especially in the past, when the springs were wound, one end had the coils close together. Thus as the spring is compressed, these coils become coilbound. As a consequence, the spring rate increases progressively with compression.
With evenly spaced coils, this does not happen. Spring rate is constant with compression.
By using suspension geometry, one can achieve whit is efffectively a rising rate spring.
It should be remembered that a rising spring rate also means that if the damper is constant rate, damping will lessen as spring rate increases.
The above explains why just cutting a loop off a spring to lower something tends to be a disasterous course of action, since it increases the spring rate and at the same time removes much of the damping, resulting in the proverbial pogo stick.