ARC8's Prototype Downhill Bike Uses a Sliding Shock Mount
ARC8 is a boutique brand based in Switzerland, best known for eye-catching paint schemes on their carbon XC and trail bikes, but recently at the Craft Bike Days, they brought along an alloy prototype with 200mm of travel. Massive plates support the front triangle while housing a sliding mechanism that actuates the shock.
The sliding bars are used to control the leverage rate and the two plates, which are bolted to the front triangle, allow for faster turnarounds when testing various pivot locations.
Similarities between the raw finish and suspension mechanism might draw you back to Yeti’s Rail-series of bikes, but this isn’t ARC8’s first go with a sliding shock. Their shorter travel bikes, the Evolve FS XC and Essential trail bikes use a production version of the system.
Jonas Muller, part-founder of ARC8 went on to explain their design ethos, “The main features are the two plates that are bolted to the down tube and top tube which incorporate all the suspension points and the BB. This allows us to independently change any suspension characteristic or geometry number by changing those plates, which are relatively inexpensive water-jet cut parts.
The current pivot locations and rail system produce a rising rate that is linearly-progressive. Along with the plated mounts, the rail system allows ARC8 to tune the kinematics.
The geometry on this prototype in particular has a 465mm reach, 622mm stack, and a 62.5-degree head tube angle. It’s also rolling on dual 29” wheels with 450mm chainstays and a 25mm BB drop - standard numbers according to Jonas.
 | It is really simple to individually tune travel, progression, anti-squat/anti-dive with that system. In current form we have 200mm of rear travel, but anything is potentially subject to change with this project. |
Bjorn Aeschlimann of Dead Rabbit Bikes built this prototype in Switzerland using 7005 alloy on the welded sections.
ARC8 admits this layout isn’t necessarily their best work because the bike is far from production. As it stands, the design team has decided that this is the optimal construction method to reach their goals.
There’s no timeline for the development of this bike and since it’s still a fresh idea, pricing and availability isn’t on their list of top priorities yet. A final version will likely look entirely different and may not follow suit with the rest of ARC8’s bikes using carbon construction either.
Will ARC8 have a World Cup downhill team in 2024? Racing is the main focus of this project and a creating team is something they would like to build towards. They’ll be drawing on a past World Cup winner to provide feedback in the meantime.
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Who writes this shit? Linearly progressive? That's the definition of oxymoron. It's also redundant, the rising rate part tells us the ratios change, don't need to add progressive unless it curves, except if it's linear then it doesn't curve...
And rising (shock) rate is never used in mtb anymore (needs a very very rampy air shock or high HBO force), unless they're using that term from the wheel's perspective, but then the -gressivity wouldn't be progressive, it would be regressive.
A _flat_ line is constant, a straight line is linear, a line that curves towards the end rate is progressive (or regressive depending on if it's a rising or falling rate, and from which perspective: shock or wheel).
This is something many bikes strive for, if you follow Neko's Frameworks project this was a subject of importance he wanted to achieve.
You could have two bikes with the same % of progression but how the curve from 0mm to end travel can allow them to feel very different from each other.
A coil shock is linearly progressive actually, as the amount of force required to compress it increases, but at a linear rate… equaling your straight line graph.
Something tells me the author has a VERY good understanding of what both progressiveness and linearity mean....But that's just my ¢¢
If we then wanted to describe how the progressive it is, we might encounter that the spring ratio (Force/compression) increases linearly. One could then call this "linear progressive" as in the article, but we could also talk about the motion ratio and say that it increases which I find a lot more precise.
Destined to be another 'innovation' that has no measurable benefit. Remember the Yeti sliding shock, cannondale driving the spring and damper via different links, um... what else in the innovation graveyard?
Switch infinity isn't dead, but it's also only there because of patents
www.mtbr.com/threads/what-model-is-this.694529