The Stark Varg Steering Stop Brace, and how it came to be

I've had my Stark Varg for a bit over two years now, and in that short time I've won quite a few races, accomplished some riding goals that wouldn't have been possible for me without it, and overall just had a very enjoyable experience with the bike.  Regardless of anyone's opinion on where this sport is heading and on E-bikes in general, there's no denying that the Varg is an incredible machine that has changed the definition of what's possible for thousands of riders around the world.  While Alta was the first to pave the way for an entirely new segment of the motorcycle industry, Stark has really taken things to a whole new level with the Varg and I couldn't be happier with the bike and the experiences I've had on it. 

With that said, every product has a weakness, and in the Varg's case that weakness is the steering stop.  The design is similar to that used by KTM and Husky, where steering lockout is achieve by having the triple clamp contact two bolts threaded into a welded mount on the frame.  Where things went wrong in this particular configuration is that there is no support material between the steering stops on either side, making the design weak and prone to breaking off of the frame under impact.  For normal riding and small tip-overs this isn't really a problem, but as I discovered after a (somewhat) mild cartwheel through some rollers, if the stop is impacted by the triple clamp hard enough it can break free from the weld on the frame.  The result is shown below.

A failure like this is a direct result of an impact force against the bolt, which then translates to a moment (or rotational) force on the welded bracket since the bolt is offset from the frame.  With no material bridging the gap between the stops, it doesn't take much force to essentially peel the weld away from the frame.  I can work my way around a TIG welder halfway decently so I was able to weld the bracket back on myself, but I can now say from experience that welding the frame on your $13k dirtbike is not something I'd like to do again any time soon.  The graphic below illustrates what caused the failure.

So this experience got me thinking, what's an easy and non-invasive way to solve this issue?  In this case, a 3D printed part just won't hold up to the structural loads, so that meant I would have to branch out into the world of CNC machined metal parts, a first for me.  Well, not really, I've designed and machined plenty of CNC parts in the past, but this would be the first time under 3DP Moto branding.  With CNC comes much higher up-front costs, so the stakes are a little bit higher than 3D printing where material cost is generally negligible, but you have to pay to play right?  I got to work designing a brace that would bridge the gap between the two steering stops, thus eliminating the moment force that caused the failure, and eventually settled on the design shown below.

As you can see the two brackets are now solidly bridged in the front, and the entire assembly is tied together in a much sturdier configuration.  Paired with aluminum mounting bolts for a bit of cushion over the stock steel bolts (credit to Billy from Luxon MX for this helpful suggestion), the brace provides support without being harsh on the triple clamps.  After riding with the brace installed for the first time it was obvious how much more solid the stops felt when contacting them in the air after a scrub or to bring back a whip, but they also had just a bit of cushion from the aluminum to dampen the impact slightly.  I now had a mount that significantly reduced the risk of failure and provided an improved feel over the stock setup, mission accomplished as far as design is concerned.  

The biggest difference between CNC machining and 3D printing is that CNC machining is considered a SUBTRACTIVE process, since material is removed from a larger chunk of metal to create the part, while 3D printing is considered an ADDITIVE process, where material is slowly built up layer by layer to create the part.  Because CNC is subtractive, I had to create what's known as a TOOLPATH, which is essentially a script of code that tells the machine what type of cuts to make, what tools to use, and how fast run the entire operation.  There are general guidelines available for all of this, but how you choose to shape some aspects of the part can leave a little bit open to artistic interpretation.  In the case of this part there are a lot of sweeping surfaces on the top near the engraving, and the method I used to program the toolpath for the ball endmill responsible for these cuts is what produced the aesthetically pleasing wavy feature.  This isn't the only way to do this, and different programmers may go about it completely differently, but it serves as an example for the level of detail and planning that can go into even a simple part like this.  Below is a quick video of the basic machining steps for one of the operations.

Now, when it comes to mass production, there's a few ways any company can go about it.  The cheapest (and most common) method is to send the design over to China, have them produce the entire thing and maybe even package it for you, and ship it over for less than the cost of the raw material in America.  This method is cheap, easy, relatively quick, and provides the highest margins by far, so it's not a surprise that most companies go this route.  But for me designing and selling products has more meaning than just finding the cheapest option.  I'm a big believer in domestic manufacturing and supporting local small businesses just like mine, so I made the commitment to produce all 3DP products right here in the USA and this project was no exception.  I have great contacts in China and Taiwan that in all honesty do fantastic work, and are great people as well, but something about machining these parts then having them anodized by a shop 15min from my house just gives a much more authentic feeling of accomplishment upon project completion.  Not to mention the reduced environmental impact of shipping parts overseas.  This may be a small and relatively insignificant project in the grand scheme of things, but the sum of our individual choices really starts to make a difference when it comes to local economies so it just seems like the right thing to do.  Thank you for coming to my TED talk. . .

So, there you have it, the Why, What, and How of the Stark Varg Steering Stop brace.  The end result was a product and design that I'm personally proud of (even if it is relatively simple), and produced in a responsible manner with a larger cause in mind.  As you can see, a lot of thought and consideration goes into offering even a basic product like this for sale, and I hope that attention to detail shows through in the overall customer experience.  Thanks for reading, and I'll see you in the next blog.