It is not a return to the past but a possible scenario for the bikes that we will see in the near future
January 31, 2023
We sometimes assume that the way forward for improving solutions is to proceed to Copernican revolutions with relative overturning of the existing one, total paradigm shift and the introduction of something totally new destined to radically improve our experience, in this case in the use of the motorbike.
However, in the field of the motorcycle and its technique, it is not always easy: one of these examples is the telescopic forkwhich despite some – excellent and interesting – proposals has never been ousted from its place in front of the engine because in fact it is the best compromise between effectiveness, weight, cost, simplicity and the proof of its substantial victory over all the various alternative solutions is which is used almost universally in competitions.
Similar speech for the rear suspension where the two lateral shock absorbers or the single central one (possibly assisted by a linkage for progressiveness) have been dominating the scene for a very long time. Also in this case the rationality, the long development over time and the simplicity of the current configurations leads them to be preferable to others which may be newer but with a non-optimal cost/benefit ratio or which require long and expensive developments to be able to manifest their theoretical advantages, for example.
However, it happens that the manufacturers decide to test and patent solutions that recall in whole or in part some systems already used in the past and then discarded or systems in use in other areas: we have one of these examples with KTM which has filed a patent application relating to an interesting rear suspension who renounces the classic shock absorber composed of a spring and a hydraulic element to rely on one crossbow.
This type of suspension in the motorcycle field is not totally new: if we have some examples in motorcycles such as the Indians of many years ago, but we also remember the cross Yamaha which, equipped with a leaf spring suspension, made a good impression on the All Japan Cross championship beginning of the 90s and which, despite these positive tests in the field, never led to mass production.
The reasons for relying on a crossbow instead of aThe classic progressive link shock could reside in greater simplicity, lower weight and a possible higher rationality of the project which could bring advantages in terms of positioning of other devices or parts of the motorcycle.
In the case of KTM the drawings show a crossbowcomposed of a single element in composite material, positioned vertically in an area where the shock is traditionally located, bound to the frame above and below by means of two linkages which, suitably sized in length and shape, determine the law of response of the suspension (and therefore his progressiveness). A threaded adjuster on the upper linkage acts to adjust the preload and, for hydraulic response, a small shock absorber would be provided.
Seen in this way, the solution is certainly rational and of reduced dimensions compared to a traditional rear suspension: it would make room for larger silencers, more advantageous placement of the air filter or fuel tank and so on, and it would certainly not be an undesirable effect if the whole assembly had a lower weight to the familiar mono+progressive linkage combination.
Source and photo: Cycle World
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