BMW R1200RT/R1250RT Forum

DaygloDavid wrote:Recently on my 2012 RT, I had the Dealers check whether the ESA Damping Settings were changing from Comfort, Normal or Sport, as, when riding, I couldn't feel any noticeable difference.

The Technician asked me to sit on the bike & bounce on the seat with the different Damping Settings selected, yes, I could feel some changes in the rebound but only small ones.

Correct Rebound Settings, https://www.youtube.com/watch?v=SXDL_jREhEE

Perhaps the BMW Technician has got it wrong, best take it to Ohlins, the experts.

All very interesting chaps, but nothing has explained why the rear end can be felt to rise when a heavier payload is dialled up on the ESA. To put it another way, does applying "pre-load" (which I presume applies compression to the spring)  increase or decrease the effective length (from lower mounting to upper mounting) of the shock or in fact does it stay the same. Think about it !!. And thanks again.

fatnfast wrote: Your starting to sound like another ' its made by BMW, nothing is better' person.

That's definitely not my view of the world! There's a whole bunch of BMW stuff that I have no time for and that a bunch of blokes in a shed could make better and cheaper.


That said, they get more things right than wrong - otherwise we wouldn't be riding their bikes!

fatnfast wrote:
No, you can't go into the menus on BMW ESA. You get what they think is correct.

In which case, my earlier post is nonsense.  I just hadn't bothered to look on the RT because the set-up seems to work fine for me.  On the Multistrada, I fiddled a lot in the detailed menus - although I'm not sure I really achieved that much.


As for Ohlins...I had Sachs (I think) on my Stelvio - that was too bouncy, even after fiddling.  I had Ohlins on my MTS - that was excellent.  It's never crossed my mind that the suspension on the RT needs much improvement, so I just ride it...


(I'm curious now - I bet the dealer can get deeper into the ESA menu and change the base set up...)


;D

The RideApart article, https://rideapart.com/articles/details- ... suspension gives a good explanation of how ESA II works.

"BMW's ESA II suspension is the first in the world to offer an adjustable spring rate. In addition to that spring rate, the amount of force it takes to compress the spring or its "hardness", ESA II can alter preload and offers on-the-fly adjustment of the compression and rebound damping; basically, you can fully adjust your suspension at the touch of a button to a greater degree than ever thought possible. But how does it work?"



"On previous suspension units, adjusting the spring rate, thus providing equal handling no matter the weight carried by the motorcycle, was only possible by stripping down a shock and replacing its spring for one of a different weight. BMW gets around this by adding a polyurethane bushing to the top of the spring, meaning suspension movement basically passes through two springs; the actual spring and the bushing. By altering the rate at which that polyurethane compresses, BMW is able to alter the effective overall spring rate."

BMW help to explain further how ESA II works, http://www.bmw-motorrad.com/uk/en/index ... &notrack=1

"This system, which is unique within the motorcycle market, allows the driver to adjust both the rebound-stage damping of the front and rear spring struts and the spring mount ("spring preload") of the rear spring strut, but also its spring rates and therefore the hardness of the spring by electronic means.

To keep operations as simple as possible and to prevent mistakes when setting the suspension, to begin with the rider only enters the loading status ("solo", "solo with luggage" or "with passenger and luggage"). The adjustment of the relevant spring mount or spring rate is then automatic, with the system coordinating both of these values.

The additional adjustment of the spring rate allows the level of the motorcycle to be perfectly adjusted to different loading states and thus ensures an even higher degree of stability, manoeuvrability and comfort. Even under maximum loading conditions, with passenger and luggage, full cornering clearance is maintained, enabling a sporty riding mode. In addition, the adjustment of the spring rate significantly reduces the danger of drifting under extreme loads.

The change in spring rate is facilitated by two springs switches in series. An elastomer element (Cellasto) in combination with a conventional helical spring below absorbs the forces during compression. The radial outward expansion of the Cellasto element is permanently limited by a steel sleeve. On the inside, an electrohydraulic mechanism is used to move an aluminium sleeve. The position of the inner sleeve influences the inward expansion of the Cellasto element and therefore its spring rate. This has the same effect as the use of two springs of different strength. If the inner sleeve sits on the steel spring, the Cellasto element will not function and only the steel spring will work. If the internal sleeve is then moved, it is also possible to vary the spring mount of the steel spring, in other words the "spring preload".

The enables the static normal position and the rising geometry to be maintained to optimum effect in all loading states."

Having spoken to Hagon Shocks about the XJ650, they advised that the twin shocks "spring rate" can be matched to the rider's weight and/or that of a pillion plus luggage.

From both the RideApart & BMW articles, my understanding is that ESA II automatically sets the "spring rate" for the loading on the bike. BMW say this is achieved by a spring within a spring, or two springs. The rear of the bike (ride height) can be seen & felt to rise when adjusting the ESA for additional load. Once the load is applied, the ride height returns to an optimum setting.

For this to happen, adjusting the "spring rate" before adding the additional load has the effect of raising the rear of the bike.
If it was adjusted with the load applied, no change would probably be noticed.

Sorry if this doesn't answer the OP's question, but it's my best effort so far.

All very interesting chaps, but nothing has explained why the rear end can be felt to rise when a heavier payload is dialled up on the ESA. To put it another way, does applying "pre-load" (which I presume applies compression to the spring)  increase or decrease the effective length (from lower mounting to upper mounting) of the shock or in fact does it stay the same. Think about it !!. And thanks again.



There's an easy solution to your dilemma.  Swap to an LC.  They seen to stay the same height.  On my earlier RTs I could never use two up with luggage as my little legs left the ground.  They were also a wallowy if pushed s bit on a Comfort setting .

Reducing the ESA load setting before the pillion has dismounted, will give the lowest ride height when the additional load has been removed.

Our Gee wrote:All very interesting chaps, but nothing has explained why the rear end can be felt to rise when a heavier payload is dialled up on the ESA. To put it another way, does applying "pre-load" (which I presume applies compression to the spring) increase or decrease the effective length (from lower mounting to upper mounting) of the shock or in fact does it stay the same.

Having read back over what's posted, I think the answer is "pre-load" is not being applied to the spring. What BMW refer to as the elastomer element (Cellasto),  has the effect of increasing the effective length of the shock until the heavier payload is added. I assume the spring length does not alter.

Thinking back to the 2007 RT without ESA, "spring pre-load" was adjusted manually using a knob under the seat.
This action did not appear to alter the ride height.

I think you are pretty much there DD.
As the write up says, the shock is basically a dual spring item, with one of the springs being a lump of elastomer, basically a lump of rubber.
The ESA action raises or lowers the overall ride height by compressing or uncompressing this. At the same time it looks like the actual spring will also be compressed/decompressed but by an amount that is not proportional to the lump of rubber. Hence the ride height increases (and you go onto tip-toes) when you change from single rider to rider with luggage etc. The rubber lump expands/gets longer and therefore the actual spring becomes more compressed (thus the preload is increased and suitable for heavier loads),but not by as much as the rubber expands.
As RT man points out that the new LC maintains a constant ride height (which is desirable of course),I think he is right about the latest LC ESA having a much more refined action. Strangely, or maybe not, this is not the case with my GS LC. But the function of its suspension is aimed differently with possible off road scenarios.
In my short amateur racing career many years ago, the most important initial assessment was setting the 'sag' on the front and rear. Basically the difference in height between an unseated and seated rider (used to be 35mm). This is where BMW ESA is more limited. They have to assume an average riders weight, average rider and pillion etc. If your very light or very heavy ESA will be limited in what it can do for you I would guess?
Richard mentions his previous Ducati ESA had far more options to adjust which in theory should produce a better ride, but didn't make much difference. Maybe the effects are purposely limited by Ducati to prevent someone giving the bike the same handling characteristics of a 70's Kwak H2? One of the best test rides I had was on the Aprilia Caponord back in 2013. They had sensors that detected swing arm movement when you sat on the bike that converted this signal into a riders weight, thus optimising the suspension even more.
I do think ESA is a good idea. I do think it is compromised by limits that BMW have to impose to make sure it works for the vast majority of riders. It won't be long before fully active suspension arrives I'm guessing.

Then again, I'm probably talking rubbish. :-)

Our Gee wrote: All very interesting chaps, but nothing has explained why the rear end can be felt to rise when a heavier payload is dialled up on the ESA. To put it another way, does applying "pre-load" (which I presume applies compression to the spring)  increase or decrease the effective length (from lower mounting to upper mounting) of the shock or in fact does it stay the same. Think about it !!. And thanks again.

I think you'll find my first post DOES explain it.  It's not difficult...


When you increase the pre-load what you're doing is increasing the weight required to get the spring to a certain degree of compression.  If you're going to put more weight on, the rear has to start higher before that weight is applied.


Pre-load does the EXACT opposite of what you think it does.  It doesn't compress the spring, it anticipates the weight that you're about to apply, increasing the weight required to compress the spring.


Think about it!!

fatnfast wrote:In my short amateur racing career many years ago, the most important initial assessment was setting the 'sag' on the front and rear. Basically the difference in height between an unseated and seated rider (used to be 35mm).

Even the experts, Ohlins & Alpha Suspension can't agree on rider sag for road use.

Ohlins recommend, front 40 - 45 mm & rear 27 -35 mm,
https://www.youtube.com/watch?v=FjGgq1z9zbo

Alpha recommend, front 35 - 43 mm & rear 30 - 38 mm,
https://www.youtube.com/watch?v=DqmI4I6 ... r_embedded
https://www.youtube.com/watch?feature=p ... i95sLZJwnw

The suspension travel on both the TC & LC RT's is the same for the front at 4.7" or 120mm & marginally different for the rear at 5.3/5.4" or 135/136mm respectively.

Returning to the damping settings and the suggestion they make very little difference. They do on the LC.  The difference between Soft and Normal is very noticeable when the pre load is on single rider.  Go to hard and it's best described as uncomfortable.  And of course it's Dynamic ESA is also semi active reacting to changes in the road surface.