Nerd Alert – Madshus Redline 3.0 Production Engineering

December testing, under the lights, with Connor Green

December testing, under the lights, with Connor Green

With the introduction of Redline 3.0 Madshus has changed a handful of things about their flagship skis, including the material layup, the groove length, and some of the reference cambers. But the most notable change that has grown out of this 3.0 project is a major shift in the camber control system used in production in the factory. This isn’t something that most ski companies would choose to make a big deal out of, because it’s a bit difficult to explain in one or two punchy marketing sound-bites. But this change in the way the ski production is controlled accounts for a huge uptick in the “hit-rate” that Madshus has in producing really outstanding skis.

First, we need to define a couple of terms.

Camber – The shape of the curve of the ski, which can include multiple compound curves from tip to tail. Camber can be assessed at zero load, or with different loads applied in different positions. But it always includes the shape of the entire ski, from tip to tail.

Flex – a single value (usually expressed in KG) indicating the load required to compress the ski to a specified residual camber height (usually 0.1 or 0.2mm). Within a given production of skis, all of the material stiffness qualities are “the same” (within material tolerances) for every pair. The measured flex of each ski is a function of its camber. But flex is only one measurement of camber, and not a very good descriptor of the most important aspects of camber as they relate to ski performance.

This video features Connor Green, a Madshus production engineer who has worked on this Redline 3.0 project for the past two years. Connor is an incredible nerd, and I have pretty strong nerd game as well. So this might get a little nerdy. If you prefer text, read on below the video.

The Problem with “Flex”

The idea that ski characteristics can be boiled down to a single number, and that “fit” can be determined by that one value and its relationship to the skier’s body weight, has always been problematic. The environment where skis are required to perform is dynamic, and the performance of skis is likewise dynamic. A single numeric value can never describe the quality or performance characteristics of a ski. And given all that can change about a ski with that single “flex value” held steady, the idea that flex can be used in a meaningful way to select skis for skiers is misguided.

If you find this photo funny, then you're definitely a nerd.

If you find this photo funny, then you’re definitely a nerd.

And yet, ski “flex” is the pinnacle of sophistication in much of the ski market, and basic metrics regarding flex values continue to dominate the thinking at higher levels of racing – even among World Cup technicians. It’s alarming how much power that single flex number can have in steering decision making at all levels of ski selection, given how arbitrary it is with respect to performance. What is even more alarming is how strongly those flex values steer the production of skis.

While every company has different systems in place for setting cambers and determining what qualities will be built into their ski production, they generally have always aimed for specific ranges of flex values. The problem with this is that efforts to hit target flex values can move the production of skis away from the very qualities that those target values were built around in the first place.

Consider a scenario where a batch of prototype test skis is built around a given camber concept, and different camber heights are produced for testing. Repeated testing yields consistent results, and skis with a measured flex value in a specific range are deemed to be best. And then a full production run is set-up, and the production team adjusts the camber using the screw settings that they know will bring the flex values into the range that has been specified, but in so doing they move the camber away from the specific qualities that tested well. This isn’t just possible; it’s very likely, because the flex value can be changed by an infinite number of different camber adjustments, and the adjustments made to target a specific flex are very unlikely to mirror the most successful camber. In the end, there is a batch of skis that don’t perform anything like the test series that was deemed to be a success.

Connor Green – the engineer at Madshus who has been working directly on race ski development since he joined the company fresh out of Harvard a couple of years ago, first made reference over a year ago to “Goodhart’s Law”; a maxim that he feels perfectly describes the problem with utilizing flex values as production targets. You can look up Goodhart’s Law on Wikipedia, but I can also save you the time. It says this:

“When a measure becomes a target, it ceases to be a good measure.”

A New Way

When Madshus first started to produce skis using the laminate material that would end up being adopted in the Redline 3.0, they started to move the marks on both camber and material reinforcement. And as they pursued the successful direction in development, the flex table that had been used in production started to bend, and eventually was totally broken. The introduction of additional laminate material changed the material stiffness of the skis dramatically, and the measured flex values got pretty wild. They started to find some extremely good skis among these new laminate prototypes, and the early race versions that they delivered to Seefeld World Championships included skis with new cambers, added laminates, and some very, very high flex values. But they were really fast skis.

In the year and a half since they first delivered skis to athletes in Seefeld, the Madshus development team has done a lot more work on refining and controlling cambers. But they took the lesson early; they decided they would “ignore” the measured end-flex, and instead focus on the combinations of camber profile and laminate that consistently produced the best results. As they moved in this directly, they realized that their success rate at producing really outstanding skis was much, much higher than previously. And so they decided that the time had come to make a big shift in their production culture, away from producing specific flex values, and toward producing cambers that they know will be capable of winning races at all levels.

Since the skis are not produced to target specific flex values, Madshus is no longer using flex values as an aid to help fit skis. Instead of utilizing flex values as a quality control metric in production, they’ve shifted to a system that assesses the entire camber of the ski through a wide range of loads. With the cambers controlled precisely and well, the camber height at different loads becomes a more important metric for “fitting” skis than the flex value. So Madshus is now printing two to three measured camber height values on each pair of Redline 3.0 skis.

Because of their choice of materials and construction method, the Madshus production is extremely consistent once it’s set-up. They’re able to control the camber with a great deal of precision and repeatability. I’ve always felt that Madshus could make whatever they wanted to make and reproduce it faithfully; It just wasn’t always clear what they wanted to make. That has changed and the change is big news for end users who don’t have a full staff of technicians available to screen dozens of pairs of skis to find that one magic pair. In truth, this change in production methodology may be a threat to our business model. We’ve always offered our best efforts at identifying really good skis at the source – selecting cambers that we felt were truly representative of the best that Madshus could produce. Connor seems to think they’re not making anything but great skis now. Good news for retailers and customers… bad news for Caldwells?

Not really. As ski companies make better skis with higher frequency, it makes our job easier, and it gives us more time to focus on specific camber characteristics as they relate to target conditions, and specific skiers. This change will save us time, and hopefully some headaches, and will help us deliver an even better experience to our customers. I think we’ll survive.


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