Pop quiz: how many bikes employ a Macpherson strut rear-suspension design these days? The answer is not many, but the French Canadians at Resistance Bikes
are working at bringing a new Macpherson strut design to the market, and it's a downhill bike no less. But wait, that's not its only trick... The Insolent features an integrated shock that's located inside
its carbon fiber toptube. Oh, and there's a belt-driven Effigear gearbox bolted to the bottom of the frame.
You know the bike is interesting when its rather exotic gearbox is only a sidenote.
As others have already pointed out, the bike's shock appears to use part of a Fox 40 stanchion tube, which is quite clever when you realize that the integrated shock is much more of a load-bearing element in the frame than if it was activated - and protected from side loads - by a rocker link of some sort. The 40mm diameter of the stanchion no doubt helps matters, but I hope those carbon chainstays are thick and beefy to assist in minimizing the side-loading of the shock. Hey Fox, how do you feel about a 40's stanchion tube being diced up and used for a shock?
If you're wondering about the large swept area of the 40mm stanchion and the added friction that would come from that compared to a standard-sized shock stanchion, I can't see it being an issue.
Afterall, a Fox 40 obviously uses two stanchions and a one-to-one ratio, so I doubt that the friction from a single, short 40mm diameter stanchion would be noticeable when you factor in the bike's leverage ratio that's probably somewhere in the neighborhood of three-to-one.
While Resistance Bikes doesn't supply much information about the design on their webpage yet, it looks like the shock itself is actually a thin aluminum body that's pushed up inside the toptube and then threaded into a cap that serves as its forward mounting point.
There are no non-drive-side photos of the bike, but you can see what looks like a single-sided bolt hole and two air valves if you look closely at the renderings, with an air piston dividing the chamber into two sections.
To support the shock, Resistance Bikes has manufactured a large bushing and sleeve that's either pressed or threaded into the back of the seattube, shown in the photo to the right.
The Macpherson Strut layout requires the seattube to sit well forward relative to the bottom bracket, so it's at quite a relaxed angle to have the seat in the right spot. No word on what they're using to control the stroke, although it looks almost like a shrunk down fork damper has been fitted inside of the shock body. With no traditional link to control the rate curve, we're eager to see some suspension graphs. We'll keep you posted on that one, but Resistance Bikes could be using something off-the-shelf or manufacturing their own damper.
There's no denying that this thing is cool looking and extremely interesting, but I also have to ask "why?" Translating the French on Resistance Bikes' website reveals that they've gone this route because ''the integrated structure of the Resistance Bikes frame reduces the amount of material required to achieve satisfactory rigidity. The direct line between the handlebars and the rear wheel transmits forces optimally.'' In other words, they're saying that the Insolent doesn't need links to achieve the rigidity that they're looking for.
What else? Well, there's that belt-driven Effibox gearbox hanging off the bottom of the bike, and slotted dropouts at the back to tension the belt correctly. It's a single-pivot design, and the main pivot is at the gearbox's output, so there's no tensioning roller required, either.
Resistance Bikes doesn't quote any numbers when it comes to weight, geometry, or travel, but the Insolent likely sports somewhere around 200mm of travel and, because it's a prototype, is probably built heavy enough to brush off any testing abuse.
Of course, this isn't the first bike with a hidden or integrated shock, but you have to admire the sleek lines of this garage-made beauty. There's no word on pricing or availability, but here's hoping that this isn't one of the many one-off prototypes that drop jaws only to drop away into the ether and never be seen again.
Photos from Resistance Bikes