Development Story - Norco's New DH Bike

Professional racers hanging out at lift-accessed bike parks to train and test isn't out of the norm, so when we spotted Norco's Sam Blenkinsop doing exactly that at the Whistler Bike Park last October it wasn't exactly newsworthy. The bike he was testing, however, most certainly was. Instead of his usual 200mm-travel Aurum and its Horst Link suspension that Sam has been aboard for a few seasons now, the New Zealander was on a radically different, high-single pivot carbon machine that employed a pull-linkage and idler pulley. Talk about going in a different direction...

In other words, the prototype Sam was riding last October (shown below as captured by a clandestine cell phone) is a drastic departure from everything Norco has done in the past when it comes to full-suspension, which is four-bar Horst Link bikes since 1995 when the FTS-1 was released. And, because Sam's rig featured a carbon fiber front and rear-end, I assumed the bike was only a hop, skip, and jump away from production, or at least from Norco finalizing the design.

Have you ever heard that expression about making an ass out of you and me when you assume something? Yeah, pretty much that.




It turns out that Norco, and Senior Designer Engineer Owen Pemberton in particular, weren't anywhere close to locking down the specifics of the prototype when I wrote that article. And even though Blenkinsop is now aboard a more refined example of what we saw in Whistler, Norco says that they're still not entirely sure of its final form. That makes it a bit hard to jump right into the yet to be named bike's details - we'll do exactly that down the road, though - but there's another story: Pemberton says that he and his development team have taken a somewhat unconventional route in bringing Sam's new bike to life, one that they've never taken before.

I visited Norco's headquarters in Vancouver, B.C., to find out exactly what he meant when he said that, and to learn more about the bike that Blenkinsop, Joe Smith, and Henry Fitzgerald, as well as Bryn Atkinson, will be on come 2017.

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From Conception to Carbon
When a new carbon fiber bike is being conceived and then produced, most of us probably assume that it goes through the following basic (and vastly oversimplified) steps: conception and design; manufacturing of prototypes out of aluminum (sometimes using tubing and materials from already existing bikes) in order to nail down geometry, details, and kinematics; and only then moving on to carbon for further testing. That's an immensely oversimplified layman's take on the process that likely has engineers cringing, but it you get the gist of it.

However, with their new downhill bike, Norco decided to skip over metal mules, going straight from sketches and then CAD designs to pulling freshly baked carbon fiber frames out of molds in Asia. And they took this route despite the fact that this is an all-new design front to back, one that includes some tricky to manufacture features. But, contrary to what the average person might expect, it was these exact features that forced Norco to go straight from conception to carbon. ''It was when we were going through the whole process, it was like, 'I think we're going to be handcuffed to just go straight to carbon,''' Senior Designer Engineer Owen Pemberton said of the risky sounding decision. ''It was agreed within the company that it's okay we take it to carbon, and if it doesn't work it's an R&D cost. We'll learn from it; we'll write it off. And we're still, to be honest, at that point. We haven't made that decision that we're not writing this off,'' he went on to say about the project.




So, without an aluminum mule, or even a rapid prototyped but unrideable frame, the development team's hand was forced by the very design that they penned. One area of the frame in particular, the 'wings' that extend down from the swingarm that the pull-links are attached to, proved to be virtually impossible to prototype out of metal, says Pemberton: ''If the shape of these weren't pretty similar, you wouldn't be able to get the geometry, and the geometry is pretty unique on this bike. If you didn't have that you wouldn't be testing what we want to test. If we tried to weld some wings hanging down this far, with the amount of force that the suspension design generates, it's just going to rip itself to pieces.'' That's a pretty clear hint that you probably won't be seeing a less expensive aluminum version of the new bike.

Frames tearing themselves apart is best avoided, of course, and while Norco's new downhill bike sports a similar silhouette to what Commencal are producing, Pemberton was quick to point out that the leverage ratio they've put to use is unlike anything else out there right now. ''The kinematics are so different in a way,'' he said of the team's work, ''and the forces that they generate are really high.'' High enough, it seems, that an aluminum version of the frame would require so much material that the geometry and layout Norco wants simply wouldn't be possible due to clearance issues, which partly explains their trip straight to the carbon ovens of Asia.




Testing The Real Thing
Manufacturing challenges aside, another concern of the engineer team's was more obvious: if you're not testing the real thing, why bother testing at all? During the early days of a bike's development, it's not uncommon for aluminum prototypes to be made using donor tubing borrowed from existing models; a toptube diced up here, or the downtube or forged elements there. The goal is to save time and money while creating a usable proof of concept, but what if your concept can't be proved by doing this? ''When you're trying to prototype a bike, and you're trying to prototype with aluminum, you're doing it cheap and using straight tubes and things like that,'' explained Pemberton of the challenges of trying to validate a carbon bike out of aluminum. ''Can you achieve the suspension kinematics with the layout that you want? Are you getting a true representation of the bike?''

That means that for Norco to build their new downhill machine out of aluminum, they'd have to open tubing molds. This is less expensive than going down the carbon route, but it's certainly not a small investment.




Let's not forget that one can't exactly just whip out some quick forgings when it comes to the linkage elements, meaning that they'd need to CNC machine parts that are actually designed to be made by a forging process that can't be used for only a few pieces made strictly for testing purposes. This prototyping stuff is tricky business, it seems.


It turns out that the new bike's relatively compact suspension linkage, at least compared to what the Aurum uses, is actually one of the reasons that Norco was confident enough to go straight to carbon. On the Aurum, the suspension elements consist of the rocker link and both the seatstays and chainstays, and you don't need to be an engineer to know that the latter two obviously do more than just control suspension kinematics. But on the new bike, the main job of its two smaller linkage sections is exactly that, which freed Norco up to commit to a full carbon fiber swingarm.

''This design allows us to be so creative with the actual feel of the suspension, just by changing the linkages,'' Pemberton said of the compact pull-link and rocker arm setup. ''We've been through, on the computer, probably close to a hundred different iterations now. What we've actually prototyped is a first suite of four with very differently shaped curves,'' which is essentially doing bracket testing of sorts but with the bike's linkage rather than just shock setup. This would have been much, much more difficult had they stuck to a four-bar, Horst Link design as used on Aurum, simply because its suspension elements do far more than only suspension-type stuff.


Margus Riga photo




An Expensive Risk
The declining costs of carbon molds also played a factor in the decision to go straight to carbon, although Norco has cut only two molds at this point - a small for Pemberton, and a large-sized mold for their other team riders. While the costs are lower than they used to be, it's still an expensive investment; the small and large-sized molds is, according to Norco, just enough investment to sort out testing and work through kinematic iterations and suspension tuning on the trail. When everything is added up, from the large, steel external molds, all of the internal mandrel molds, bonding jigs, machining fixtures, etc, the investment in a full size run of a new carbon chassis can easily get into the six figure range.




That number puts Norco's venture, or any company who invests in carbon frame production for that matter, in a new light. It likely also had Pemberton sweating bullets while he waited for the first carbon frames to come out of the mold and be built up, and he made sure that he was the first one to swing a leg over his creation. ''There was a lot of nervousness in how it was going to ride,'' he described of that first day on the bike.

''I wanted to be the first person to ride it, especially because it is so different. I wanted to be first, but especially before we put pro racer on it,'' which is an understandable concern when you're hoping that a few top World Cup racers are going to be more than just okay with what you've put together.


Margus Riga photo

And how did it perform? After some early fiddling with linkage and shock combinations, Pemberton came away extremely happy, he said. Only then was Blenkinsop given the go-ahead, which is when we spotted him pushing the new machine onto the chairlift at the Whistler Bike Park. The word from Pemberton is that, after a brief getting to know each other period, Sam was impressed. But, regardless of the new bike's performance, Norco stressed that they'll be keeping the Aurum in their catalog for the foreseeable future. That's not a shock given their investment in the Aurum, and especially because of the race-focused goals of Blenkinsop's new machine.

We'll have more on Norco's new downhill bike in the near future, including all the details of its suspension, geometry, and construction.

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