GS Exclusive Dynamic ESA Next Generation

ChazzyB said:

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.

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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

Charles Martel said:

I made the same conclusions.

I'm not sure what the differences are, maybe the Rallye has more travel ?

Lets hope the "exclusive" gets some attractive colours at some point, because at the moment its dull dull dull.

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I believe that for 2017 the base Rallye model had the same suspension as the base GS, and the Exclusive and TE (the same apart from paint) and the Rallye Sport came with many optional extras built in and also had the same suspension as each other. In addition the Rallye Sport could also be specified with the sports suspension which confusingly is not part of the Rallye Sport spec, but an additional option. This gives a higher spring rate and longer suspension travel, and BMW only recommended it for serious off-road use.

It seems that for 2018 BMW have changed the confusing name of the Rallye Sport to Rallye TE which brings it in line with the GS TE, so no longer causes confusion with regard to the sports suspension option which is available on the Rallye TE as a £300 option.

Thanks fred . appreciated

( if the KTM had shaft drive I wouldnt be bothering with any of this! ..... but until then, there really is only one brand of bike worth buying imho, (for this type of cross-continent riding) )

Charles Martel said:

Thanks fred . appreciated

( if the KTM had shaft drive I wouldnt be bothering with any of this! ..... but until then , there really is only one brand of bike worth buying imho , (for this type of cross-continent riding) )

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I came to a similar conclusion, which is why I bought my first GS in March this year. I like the Honda DCT system having experienced it on their NC750X, so considered the Africa Twin, but the rest of the spec did not appeal. I also looked seriously at the KTMs and the Multistrada but they are probably a bit too sporty for what I want, which is versatility and two-up comfort.

I had an interesting discussion with a Honda rep at the NEC about this. I said to him that in my opinion the Africa Twin only really competes with the GS for those GS riders seriously interested in off-roading, probably representing no more than 10% of GS sales. For the other 90%, who like me use the GS as a versatile road bike/tourer, then I think the AT just doesn't tick the boxes, and really does not compete. I told him I would want a road biased version of the AT with a bit more power, tubeless tyres, semi-active suspension and more pillion comfort, plus of course a DCT option. I could live with the chain drive. He didn't give me the impression that I should hold my breath waiting for such a beast!

has1971 said:

I too had a 2015 1200 gs te standard height and loved it, I now have a 2017 Rallye with standard suspension and chassis. I don't have a problem with the ride height at stand still but on hard cornering with suspension in dynamic mode the rally foot pegs touch down indicating the suspension must be a little softer as I never had this problem with the 2015 bike although on the te I did set the suspension to rider with luggage to avoid the pegs touching down.

I do think the later version dynamic esa is a much better ride quality but I would prefer to have some manual adjustment.

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Take out another bike on a demo to compare with yours.
My 03/17 lowered GS TE had the rear suspension unit changed at it's 6k service as it felt like it had a weak spring and I was grinding the pegs because the rear was sitting too low.
I think the latest ESa is a step backwards as it has removed rider input, the damping is either too soft or too hard, the auto preload works fine, on the previous bike middle was the goldilocks setting for me 90% of the time and I could go soft or hard from there when needed.

Why are BMW not using a modernised version of Citroen’s hydraulic suspension. The tech is well proven and you get virtually instant ride height adjustment. Late models lowered at speed lifted on rough roads and even had active anti roll. The latter would not be much help on a bike but the basic tech has existed since the 1960s


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Bendy toy said:

Why are BMW not using a modernised version of Citroen’s hydraulic suspension.

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Maybe BMW haven't thought about it?

ChazzyB said:

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.

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BMW are a bit cloudy on their blurb.... But I think you have nailed it here Chazzy

Bendy toy said:

Why are BMW not using a modernised version of Citroen’s hydraulic suspension. The tech is well proven and you get virtually instant ride height adjustment. Late models lowered at speed lifted on rough roads and even had active anti roll. The latter would not be much help on a bike but the basic tech has existed since the 1960s


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It would be easier to ask Citroën why they've dropped it than wonder why other manufacturers haven't picked it up. It was really very good though!

I don't know the technical details of the Citroen system, but it is possibly no longer used on cars and maybe wouldn't be practical on bikes because it required a powerful hydraulic pressure pump, an accumulator or reservoir for quantities of pressurised fluid, fast acting electrically actuated hydraulic valves, plus large hydraulic pipes going to each suspension unit.

I think this would be classed as an active suspension system as it actively sets the wheel positions whereas BMW's is a passive system using springs to control movement with the semi-active component just being the way the damping can be dynamically modified to more accurately control the passive spring based system than conventional fixed damper valving.

The 2017 gives a vastly superior ride to the 2014 for smoothing out the bumps. Handles just as nice too. The 2014 was either comfort, with things getting a bit out of hand when pushing on, or hard with great handling definitely at the expense of smoothing out the road surface. 2017 has the balance just nice. Big thumbs up from me.

The full Citroen system had a hydraulic accumulator because it had powered brakes, steering and suspension. The hydraulic pump was smaller than a Japanese motorbike starter motor. It could be driven from the alternator belt. Suspension damping was a normal system but hydraulic oil circulated so dirt and wear debris didn’t build up.
Suspension itself was gas spheres (cheap and easy to replace) but could have been normal springs. Ride height was hydraulic. No pressure = zero height.
Brakes and steering needed the accumulator but suspension only would not need anything so large.
However on a bike, the savings in ABS equipment, ultra high precision suspension would offset the hydraulic costs. A bike would probably gain from the powered brakes. Smaller brake parts = less unsprung weight.
The real reasons will be offloading warranty risks. Parts & systems makers like Bosch feed a traditional market but more importantly they pick up the warranty costs when their stuff fails.

Interesting details on the Citroen system, and sounds like a version of that might be practical for bikes. It would have to be pretty fail safe for a bike though - you might expect to be able to tolerate a sudden loss of suspension when on four wheels, but it could be disastrous on a bike. Non-telescopic front suspension would also probably be needed for this to be practical.

fred_jb said:

Interesting details on the Citroen system, and sounds like a version of that might be practical for bikes.

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Except that, whilst it was exceptional, Citroën no longer see it as practical for their cars.