Hi, here's another one of my long posts. Please bear with me.
It took me a while to completely understand ESA, and then I studied aftermarket shocks. Here's why I decided to go with the latter. I'm not discussing price and value for money, thats' up to each individual.
First : SPRING/DAMPING QUALITY. Buying into the ESA system doesn't mean that you are buying a better spring or damper than standard BMW. It just means that instead of manually changing preload and damping as you can on the standard spring/damper, small motors do it for you at the push of a button. Nobody knows if the spring or damper are of any better quality than the standard BMW suspension.
Then : PRELOAD. BMW has estimated (= scientific guess) how much a solo buyer weighs, and has called this the 'solo' position for ESA. If you are significantly heavier the 'solo' position will give incorrect preload, and you will have to ride around with 'solo+luggage' as a minimum. Which of course implicates that the other settings will not match either. But, if your solo weight is less than the BMW estimate, the 'solo' position of ESA will always be wrong. A rider who weighs 70kg or less will find an ESA equipped bike unpleasant to ride with. This basic error is the reason why the aftermarket is providing systems that match the 'solo' position to your specific weight. Examples : there's WESA by Wilbers, and Ohlins have their TTX electronic suspension that can be adjusted to specific rider weight (the Ducati Mulistrada 1200 offers this adaptability).
But let's assume that the riders' solo weight coincides with BMW's estimate, then there's still the question what to do with additional weight not coinciding with BMW's definition of luggage and pillion. There is a difference between riding solo with topcase loaded, and riding solo with all cases loaded, but that difference isn't considered by ESA. The logical conclusion is that ESA only has rough correctness when it comes to preload.
What about BMW's claim that ESA on the GS allows 15 free choices ?
'On road' the weight on the bike is a GIVEN factor (you decide how much weight you put on the bike) and then you MUST adapt preload to the weight; there isn't really a FREE choice what position you put preload in.*
If you ride offroad the terrain dictates what position you put preload in. Again, a GIVEN factor, there's no free choice. What remains is a free choice between the 3 modes of damping.
*
Even when a rider decides to use a different setting than BMW prescibes, he'll still use that same setting for that specific weight. Again, a given.
So let's talk about DAMPING.
First of all, the ESA system doesn't take changing temperatures into account, which means that the damping characteristics of each position (comf/hard/sport, or soft/norm/hard) will change with the change of season, as the oil viscosity of the damper changes.
BMW has chosen these three damping settings with big differences damping wise. The customer really feels the difference and says 'Wow this really works' , which is OK by itself.
The disadvantage of these big differences in damping steps is that some positions don't necessarily please the rider. If you browse through different posts and read comments of owners you'll often find the phrase : 'I don't use the 'X' position, because it's too hard/soft'. Some riders state that they always leave damping in the same position. This indicates that for some owners the choice of damping is limited to 2 positions... or even less. And then you may wonder why you'd spend money on settings or choices you will not or hardly ever use.
Now, there are some clear advantages to ESA :
- userfriendly : at the push of a button
- ease of change : for riders who alter the charge on their bike several times a day, it's heaven being able to adjust preload pushing a button (instead of having to turn a knob)
- changing damping characteristics on the fly : not having to stop to fiddle about with damping when road surface suddenly changes from bad to slick (or vv).
- preload or damping are always adjusted at front and back together, so a rider can't put the bike in a 'bad' setup
In conclusion, the ESA system is an extremely easy to use system with a few shortcomings (preload), and with a limited amount of possibilties (damping).
Compare this to the standard BMW/aftermarket suspensions :
- preload can be set EXACTLY according to charge on bike, even in small increments. Dynamic sag will always be right, be it riding solo, solo + topcase, solo + sidecases, solo +all cases, solo + pillion, solo + pillion + topcase, and so on... The disadvantage being that the rider has to know what he's doing. As preload is always adjusted before take off, there's no real disadvantage in user friendliness.
- damping can be adjusted not in mere 3 steps, but in extremely small steps (Wilbers : 22 steps). The beauty is that while I ride around with damping between positions 11 and 16, the next rider may like positions 14 to 20. Individuality rules. The disadvantage is that you have to stop and get off the bike if you want to change damping somewhere en route.
- damping can be adjusted to change in temperature. I use less damping in winter, compared to summer. That way my bike behaves the same throughout the year.
- most aftermarket shocks are of better-than-BMW-standard-shock quality
You may have guessed : I preferred a quality shock with a wide range of possibilities and some user unfriendliness (Wilbers) over the ease of use with limited possibilities and possible wrong preload (ESA).
Sincerely : I'm happy that so many owners of ESA are satisfied with what they bought. I wouldn't want it any other way.
