Science 101: Head Clamp Design

The head clamp is one of the most critical designs when a navigation tower is put on a bike. Usually, bikes like the KTM 950/990 ADV or the 640 ADV, already have a welded block on the frame which allows the after-market kit manufacturers to support the navigation tower. When this is not possible, the manufacturer has to find his own solution. But what are the steps? Read on!

There are multiple ways to attach a navigation tower, welding, drilling and tapping, non-destructive ways etc. Welding is good, but needs to be done by professionals and in reality the HAT (heat affected zone, which is the zone that was affected by the immense heat of welding, which changed the properties of the material) needs to be neutralized by some kind of annealing. Also try to weld on a cast part and without proper annealing and without knowing the full properties of the alloy, and you’d be looking for big trouble in the long run. Drilling and tapping is ok, needs some fiddling but it is always possible to be done in house and the non-destructive ways are usually the easiest, yet not the strongest, as they are heavily designed dependent. Drilling and tapping is also misjudged. We tend to think that by drilling something we are making it weaker, and that is true in to some extent, but (Fact ‼️ ) because you are now putting two sandwiched plates in the headstock, it’s actually stronger than before.

Method of manufacturing is also of utmost importance. CNC? Sheet metal? 3D printing? All have advantages and disadvantages. CNC is the best method at present to create a strong part, without being limited to the design (compared to sheet metal). It’s expensive though, so not a lot of CNC parts around the block. Sheet metal is cheap, quicker and easier, but the material is already ‘damaged’ by the cold work in the bending process and the welding (if done). Again, there are techniques to increase the fatigue performance of such a products, but special tooling is needed. We do it in all our welded back plates to give them some ‘ooomph’ in their fatigue performance. Actually this technique, which is used by all automotive manufacturers, aerospace, F1, and whenever fatigue performance needs to be increased, was studied by our personnel as far back as ten years ago when custom software was developed back then to predict the residual stresses in carburised gear steels. There is a PhD thesis sitting somewhere in Stephenson’s Library in Newcastle Upon Tyne. (You can call this a #TBT Throwback Thursday as well…). So, better to put it to some good use!

3D printing is utterly expensive at the moment (to print metals), but doable and allows maximum design freedom.
Can you mess up with any of these? Yeah baby! Big time! The design and method of manufacturing go hand in hand. Usually, in most aftermarket parts you will see cloning. In aesthetics sometimes it makes sense to clone the looks, because of the parts that are used (a skid plate must match the tank profiles for example aesthetically). But in engineering, more often than not (there are exceptions, indeed), but as said, more often than not, a cloned part means that the manufacturer knows squat about what he is doing. You can’t clone a Sheet metal part and make it a CNC. Well, you can, but it does not make sense. Same for 3D printing. Printing a part the exact shape as a composite or a CNC part, is a rookie mistake. It negates the process benefits. For example, let’s say we print a clone of a CNC part. 3D printed was devised to allow maximum shape freedom, hollowed parts (that’s a study on its own…), 100% shape freedom etc. By cloning a CNC parts you may as well do it in CNC.

3D design for printing, is an art of its own and it will take a while for us, traditional CAD workers to adjust to that. With the help of #Autodesk and #GenerativeDesign, (Beta testers forever!) we put these tools into practice to get a shape that makes sense and performs as intended in this, tough, environment. (you can learn more about how we are shaping the future, now, in this link: https://www.autodesk.com/solutions/generative-design-video )

So what are the benefits of our patent pending spider clamp? It is adjustable, you don’t need to fiddle with anything on the bike big time (no switch removal, no radiator expansion tank removal) and with 4 M6 bolts and a U-bolt you are good to go. Now, how do you tight the assembly plays an important role. Hence all the torque values are mentioned in the manual. Yes, we all have a ‘hand-wrench’ in our body, and indeed some people are very close to torque wrench values, but let’s leave this to the pros. When something is tightened, forces are generated. Parts are in tension, friction is created, all sorts of things happen. A lot of people tend to think that a torque wrench is not necessary. Big mistake. Friction will dictate the performance of the assembly in the long run and how the assembly performs when you, sometimes…, crash. We have crash data from our 701 Xplorer and Rally bikes, even from #PalAndersUllevalseter ‘s rally bike in Africa Eco Race, to prove that our head clamp worked as intended. In another #crashstudy you will actually see why our Aluminium towers will allow you to at least go back home and fix it, or go to the bivouac where your team will get their hands on the bike, without anything hanging off.

Have a #goodriding weekend.

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