Everything You Need to Know About Norco's New DH Bike

Alright, it's not really a ''first look'' given that we spotted Norco's new downhill bike, or an iteration of it at least, back in October of 2016. At the time, Sam Blenkinsop and a handful of smart people from Norco were testing the design at a mostly deserted Whistler Bike Park; mostly deserted except for one eagle-eyed rider and his potato phone, that is. And after much pestering on my part, Norco finally let me into their North Vancouver HQ in February of last year to see the prototype and throw a bunch of questions at their engineers.





There are two complete bikes to choose from, with the BoXXer World Cup and X01 DH-equipped Aurum HSP 1 going for $7,999 USD, and the Aurum HSP 2 selling at $5,499 USD with its BoXXer RC and GX 7-speed drivetrain. But don't forget that each can be had on 27.5'' and 29'' wheels, too, so there are actually four complete models to choose from.

And if you want to build up your HSP with parts of your choosing, a frame kit (incl. shock, headtube insert, axle) costs $3,299 USD.


Ross Bell photo

Suspension Design

If you're not familiar with Norco's previous bikes, the Aurum HSP's 200mm-travel, high single-pivot and idler layout is their first radically different, non-Horst Link bike that they've designed since 1995 when the FTS-1 was released. That's twenty-two years of Horst Link'ing... and now this, which begs the question: why the drastic change?

According to the press release, ''The high-single pivot design provides a rearward axle path, lengthening the wheelbase when the suspension is engaged and thus carrying maximum speed through the rough without compromising on control,'' which kinda matches what we've been told about high-pivot bikes for ages. It's also a theory that others have put to good use, of course, from Sunn to, more recently, Commencal, and a bunch of others in between.




What makes the HSP different to those examples, according to Senior Design Engineer, Owen Pemberton (who has since left Norco), is its suspension geometry, and particularly its progressive nature: ''The kinematics are so different in a way, and the forces that they generate are really high,'' he said when I questioned him.

The HSP's linkage actually works the opposite way to the bike you're probably thinking of, Commencal's Supreme DH V4. So instead of compressing its shock from below as on the V4, the A.R.T pull-link tugs on a rocker that compresses the shock from above to deliver 200mm of get-out-of-trouble.


The high main pivot would also cause a boatload of chain growth and pedal kickback if Norco didn't use an idler pulley to route the chain up and over the pivot, which is why most of these types of designs require exactly that. It likely also has something to do with that time Blenkinsop was spotted running an interesting looking idler pulley add-on setup on his Norco Aurum at a New Zealand National race back in January of 2016. Norco also says that ''tailored anti-rise makes the bike squat under heavy braking to counteract the forward rider inertia.''


Ross Bell photo


Frame Details

This bike's predecessor, which also goes by the Aurum name, looks downright conventional compared to the HSP's ultra-low slung, swoopy frame. I mean, could the top tube drop down any more than it already does? If it wasn't for the fin-like seat mast, you might mistake the thing for an adult-sized run-bike on 'roids. The frame went straight from computer to rideable carbon prototype, which is a first for Norco and not how it's usually done. No steel or aluminum test mules, or even a rapid-prototyped model, were created; it was all or nothing... No pressure, though.

''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,''' Pemberton said when I interviewed him back in 2017. He was largely referring to the 'wings' that extend down from the swingarm to where the pull-links are attached, a part of the frame that, according to Norco, proved to be virtually impossible to prototype out of metal. It's probably safe to assume that there was more than just a bit of suspense as the first HSP frame came out of the mold.


Ross Bell photo

The carbon frame is made using the same 'Smoothcore' mandrel technique that's employed to make some of Norco's other high-end bikes. In short, rather than using bladders that can sometimes not provide enough compaction in complicated areas inside the frame while it's in the mold, a heat-sensitive mandrel is placed inside that's said to apply more evenly spread pressure to the layup. This technique should result in a smoother surface inside the frame, hence the Smoothcore name.


Ross Bell photo

Norco is far from being the only brand having their frames made using this method, of course, but they are doing something else that's pretty interesting... Rather than building all the frame sizes with the same carbon construction, each size gets a unique layup. In Norco's own words: ''Size-Scaled Tubing enables our engineers to calibrate frame stiffness to the weight of the prospective rider by increasing tube profile dimension in proportion with frame size.''

So, because the large-sized frame is obviously longer than a small, it'd require more material than the small to meet rigidity requirements and vice versa. They're also using a resin that they call 'ArmorLite' during the bonding process that, according to Norco, is especially resistant to impacts. There's a bolt-on guard on the lower end of the downtube, too.




When I visited Norco's HQ last year to learn about the new Aurum, they were especially keen to point out a few mechanic-friendly features that the prototype was sporting, and those have also been carried over on the production version, too. The locking main pivot, which should refuse to come loose, is clever, and they went with externally routed housing front to back to have upkeep be headache-free. More interesting are the small reliefs machined into the inner face of the bores that will make it easy to get the old bearings out.



Two Wheel Sizes, Two Different Frames

When I read that Norco was going to offer the HSP with both 27.5'' and 29'' wheels, I assumed that the frame was the same for both and the deed was done by way of a geometry adjustment feature of some sort. That'd be the most cost-efficient method, I assume. Instead, each wheel size gets its own front and rear triangles but, because Norco can change the pivot locations between the two, they can use the same suspension linkage (in an ever so slightly altered layout) regardless of wheel diameter. This is arguably a more optimized approach, of course, but there won't be any swapping between wheel sizes on the same frame.




The HSP's suspension isn't adjustable as far as different shock mounting points go, but the bike's geometry can be tinkered with by way of an insert at the headtube that changes the reach number by 8mm. If you do decide to go longer, you'll also be dropping the bottom bracket by 1.3mm, increasing the stack by 1mm, and the wheelbase by 7mm.

Geometry is, as you'd expect, all about going warp speed down steep, fast terrain. There's a 62.5-degree head angle across the board, and a M/L frame sports a 445mm reach with 27.5'' wheels (the numbers vary slightly on the 29er). You can also add 8mm with the aforementioned offset headset cup. One number that might stand-out to you is the HSP's rear-center length that probably looks quite short; it's just 420mm on the M/L. It's not actually that tight, though, because that measurement is taken with the bike's rear suspension fully unweighted and extended, just as with any other bike. But with such a high main pivot, the rear-center length is going to grow as the bike goes into and through its 200mm of travel, so 420mm at top-out is actually shorter than it'll be at its sag point.




And speaking of rear ends, Norco is also doing size-specific rear-center lengths, something they call 'Gravity Tune' that was also used on the previous version of the Aurum and other models. ''Traditional frame designs disregard rear-center lengths when changing size, forcing riders to compensate over the bike,'' they explain. ''Gravity Tune adapts the front-center/rear-center ratio across all frame sizes, effectively optimizing geometry and rider weight distribution regardless of rider height,'' so the small-sized HSP gets a tiny 400mm chainstay length (at top-out) and Norco adds 10mm to the back end of each frame size up to 430mm for the L/XL.




I think there are a few notable things to buried in the Aurum HSP's debut, aside from the bike itself. Norco is still one of the few companies that vary rear-center length for each frame size with their Gravity Tune geometry, and the different carbon layups for each size is also worth mentioning again. Most important, though, is that rather than including some sort of geo-adjusting add-on, they've gone and manufactured different frames for 27.5'' and 29'' wheels while also tweaking the suspension on each to keep the feel consistent. Having not thrown a leg over the HSP yet, I don't have a clue as to how it performs, but you can't say that Norco didn't cover the details.

So, what do you make of the Aurum HSP and its high single-pivot suspension design?

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