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Gracey Hemstreet, Lucas Cruz and Mark Wallace have been testing an all-new prototype aluminum downhill bike from Norco, featuring a 6-bar linkage suspension layout. And, Lucas Cruz just won the Canadian Downhill National Champs aboard his. Here’s what we’ve gleaned so far.
Norco’s Prototype 6-Bar Linkage Downhill Bike
Until now, Gracey Hemstreet, Lucas Cruz and Mark Wallace have been piloting the Norco Range DH at UCI Downhill World Series events, which is essentially a long-travel version of the Range Enduro Bike, adapted for the demanding tracks with a 200mm travel dual- crown fork and a longer stroke shock. Now, it seems, the team is to benefit from a dedicated downhill bike that runs an all-new suspension design.
Bidding farewell to the linkage-driven single-pivot of the Aurum HSP, and the four-bar linkage of the Norco Range, the as-of-yet un-named prototype sections a 6-bar linkage design, wherein the main pivot is positioned high on the seat tube. Indeed, Norco is sticking with a high-pivot, seemingly very happy with the majority rearward axle path it delivers.
It does of course mean that an idler pulley is required to route the chain close to that main pivot, dissociating conflicting forces from the drivetrain and suspension – ie, reducing kickback pedal. On the prototype, an idler pulley positioned concentric to the pivot, is utilized – with 22 teeth, it is very large by current industry standards.
Only the Nicolai Nucleon 16 with the Lal Bikes Supre Drive runs an idler pulley this big, in a presumed bid to reduce friction.
On the Norco prototype’s linkage, we count seven pivots, if you include the one on the short yoke (dark blue) that is driving the shock. The shock is positioned very low in the frame, driven by that yoke that is itself driven by a link (orange) that will rotate counter-clockwise about the main pivot as the bike is pushed through its rear wheel travel.
Connected to that link, about two thirds of the way up its length, is a bar (pink) that couples the movement of the lower linkage (blue) to the orange link. It moves through space as the lower linkage (which importantly is not articulating about a BB concentric pivot) extends away from the front triangle to extend the bike’s effective rear-center length as it is pushed through its travel. And, let’s not forget there is a pivot on the chainstay, as well.
I shan’t be commenting on what kind of kinematic is likely to arise from such a layout, but it seems to work nicely with both air and coil shocks. Lucas Cruz just won the Canadian National Champs aboard this Norco prototype, sprung by a RockShox air shock running a very, very large air can – as compared to the modestly-sized air can we see on the Super Deluxe Ultimate Air Shocks, that is. Meanwhile, 2nd place Mark Wallace’s bike was coil-sprung.
Also noteworthy is that a Norco Development Engineer involved in the creation of this bike, Kirk McDowall, filled third place on that same podium. Chapeau.
Unfortunately, Gracey Hemstreet suffered a suspected head injury, and did not complete a race run.
The snippets of information we’ve collated from the Norco Factory Team’s social media indicates that the team will be switching to this new bike for the rest of the Downhill World Series, kicking off in Pal Arinsal, Andorra, on the 24th August.
Until then!
norco.com
