I agree with Fred 
1200 GS TE Exclusive suspension
- Thread starter Engineer
- Start date
So just checking, does the 2017 1200 GS TE have Dynamic ESA II?
Yes. Mine certainly does O1/03/2017
Ok but I can find no reference to spring-rate adjustment on the BMW website, only auto 'pre-tension' (pre-load) and auto damping.
Can you point me to the bit where adjustable spring-rate is specified on the TE, I can't find it
fred_jb
Registered user
Ok but I can find no reference to spring-rate adjustment on the BMW website, only auto 'pre-tension' (pre-load) and auto damping.
Can you point me to the bit where adjustable spring-rate is specified on the TE, I can't find it
The link I posted earlier has an explanation of the preload/spring rate adjustment: http://origin.bmw-motorrad.co.uk/uk..._detail/suspension/item_esa_II.html¬rack=1
This web page describes the ESA II implementation as found on the pre-2017 bikes, because it talks about Comfort, Normal and sport damper settings, but I find it inconceivable that the current development of that system with the DYNA and ROAD damper settings and AUTO load settings would have lost the spring rate adjustment. To quote from that web page:
"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."
I think that is the clue as to why there is no separate mention of spring rate adjustment. In the previous system the rider simply specifies the nearest of the three load settings to their situation and the combination of preload and spring rate is set appropriately. I think BMW suppose that it would get confusing to talk about preload and spring rate as separate things when the user has no control over them individually, so they gloss over this, which in a way is under-selling their system. I would assume this is the same for the current system, except that there is now a range of adjustment of these two parameters and the auto system can select any values needed for the current actual measured loading, rather than the rider having to specify one of three presets, none of which may be exactly right for the actual load.
Fred
PS: The TE has every possible option, so will have the full ESA capabilities.
I am pretty certain that the pre 2017 GS does not adjustable spring rate - I think the ESA II was hossack fork bikes only???????
Looking at my 2015 TE there is no sign of any mechanism for adjusting the spring rate, it is a single spring - electrical adjustable damping and pre-load yes but not spring rate as far as I can see.
I would like to see definitive info that says the 2017 TE has adjustable spring rate.
fred_jb
Registered user
I would think the preload/spring rate adjustment would only apply to the rear suspension unit, so I'm not sure that the style of front suspension is relevant. However, I do agree that it is very difficult to find definitive information from BMW. I am simply going by the web page I linked to which I assumed was a generic description of the system. If that description does not apply to all ESA II equipped bikes then you may be right, but I think it would be strange to provide this adjustment on say the RT, but not on the GS, when the suspension systems, engines, etc on all the LC bikes are otherwise so similar.
fred_jb
Registered user
After a lot of searching I've not been able to find any definitive information on this, but from the following, admittedly well out of date article, I'm beginning to suspect that not all ESA equipped bikes have the adjustable spring rate feature: https://rideapart.com/articles/details-bmw-esa-ii-electronically-adjustable-suspension If the GS suspension in fact doesn't have this, then it is even more remarkable how well it works with varying loads.
Fred
Fred
Any GS1200 that has electronically controlled pre load uses the 'squeezed rubber' mechanism, this is used on the rear only, there is no pre load adjustment made at the front. Some bikes with ESA only adjust damping eg 800 gs.
You may be correct but where did you get that information from?
Over the years, reading articles, being nosey, talking to BMW and others and looking at bikes.
I have spent many years tearing round race tracks and roads, one of my 'things' has always been suspension so I take an intrest in it.
The spring is a coiled length of heat treated steel - I can't see how you can vary the rate once it has been manufactured. If the bike had air 'springs' then absolutely - but it doesn't that I can see.
The only other way would be to have an electronically adjustable bottom link, but I can't see that happening any time soon.
You can vary the spring seats to raise or lower the bike, but that isn't the same as variable rates.
I think there is some confusion in the thread.
No confusion. From crotchrocket in an earlier post.
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".
My version.
Imagine a piece of rubber squeezed into a tube closed at one end and a spring in the tube up against the rubber on the other, if you make the tube a little bit narrower it makes the rubber a little longer and stiffer. this pushes the spring down a bit (ride height) and stiffens up the action as a whole (spring rate).
fred_jb
Registered user
Well after speculating at the computer last night, and quoting an article on BMW's web site, I had a look at the actual bike this morning. While it has what looks to be a fairly conventional motorised preload adjuster, like Engineer, I am now doubting that this incorporates a spring rate adjustment mechanism, which is a bit of a disappointment.
I'm still impressed with the suspension, and this does not affect the point I was trying to make when I first mentioned spring rate adjustment - namely that when a bike has automatic preload (and possibly also spring rate) adjustment, then the appropriate damping parameters also have to be set automatically so that they match, which means that it is not really possible to give riders the full manual control over damping which some apparently want. Same issue with the dynamic damping adjustment. I can therefore understand why BMW now only provide two user accessible damping settings, which I think are not actual settings as such, but just there to express a preference to the automatic systems, telling them to bias their automatic damping adjustments one way or the other.
fred_jb
Registered user
I agree that if there is a spring rate adjustment then it is almost certainly only at the rear because as the load on a bike is increased it disproportionately loads the rear suspension. When making sag measurements on bikes in the past I have seen situations where adding load increased sag at the rear but left the front unaffected, or even with slightly reduced front sag. In this situation I have had to reduce front preload and/or drop the front by raising the forks in the yokes to help level the bike.
fred_jb
Registered user
Looking at the diagram here: https://rideapart.com/articles/details-bmw-esa-ii-electronically-adjustable-suspension I suppose it is feasible that what looks like a standard preload adjuster could be dual purpose for spring rate and preload. The inner metal tube that is wound down to stiffen the rubber collar looks like once fully through the rubber and providing its maximum increase in spring rate, it has further travel available, so could continue moving down to then exert pressure on the spring seat and thereby increase spring preload. This would mean it could not adjust spring rate and preload separately but would have to first increase spring rate and only if that were insufficient would it go on to increase preload.
I agre that in the picture it looks though that could happen, in the actual shock in action I doubt it would work quite like that as the two could impact on the compression stroke and would be felt as a knock. The picture does not show any compression or distorsion in the 'Elastogran' and is just showing you the idea, I don't think it can be taken to be exact.
Elastogran....... Who thinks these names up, sounds like my mother on the rack.
Elastogran....... Who thinks these names up, sounds like my mother on the rack.
I took a look at my bike today (2015 TE) and it looks like a simple motorised pre-load adjuster to me too - you see the reason why I have been querying the adjustable spring rate theory? Also none of the current BMW 'blurb' on their website gives any indication of automatically adjusting spring rate - wish I could find a definitive answer, perhaps an email to BMW might clear up the confusion.
I asked the service manager at my dealer if the GS had an adjustable spring rate, after a moments thought he said that it only has adjustable dampers and preload. I think that the Elastogran thing was a limited experiment on the K1300 range of bikes only and called ESA II, there has been no reference to it since.
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