Downhill mountain bike racing is full of secret, but not-so-secret mountain bikes. A couple of years ago, we saw Pivot’s unique Phoenix platform, and for years, we’ve seen Specialized working on something rather different. Now, the brand has pulled the covers off its Demo 11, and much like the Levo Evo, it’s built for composure and ultimate predictability, thanks to its very unique HighGear and OBB suspension layout.
Let’s dive into HighGear and OBB
What makes the Demo 11 so remarkably different from other chain-driven downhill bikes currently on the circuit is its HighGear and OBB suspension setup. It’s a kind of gearbox/jackshaft system (that reminds me a lot of Honda’s old bike) that’s said to boost ground clearance by 30mm. while removing drivetrain influence on the suspension… so pedal kickback.
Inside that ‘gearbox’, for lack of a better term, are all of the drive-producing gears. So there’s a small chainring that’s mounted to the crank spindle, which then drives a jackshaft. On the jackshaft is the final drive ring, which transmits power to the rear wheel via a regular ol’ chain. Spesh isn’t going for the Gates Golden Purse here. The brand goes on to say that the position of the final drive ring keeps the chainstay length constant throughout the travel, keeping chain forces well away from the suspension’s movement. The small initial drive ring then allows for that increase in ground clearance, while the cased system protects the forward-most part of the drivetrain from damage.
As for the suspension kinematic, Specialized says that it has achieved a 24% progressive leverage curve. That curve has been chosen to help keep the bike composed while able to cope with heavier compressions.
Then, OBB (Over Bottom Bracket) is a pretty wild linkage setup that has allowed the brand’s designers to really tweak how the suspension works, with each facet (axle path, leverage rate, braking behavior) being independently tunable by the team, apparently. Specialized says that it has managed to develop a bike that’s predictable, composed even under heavy braking, while reducing rider input and saving energy late into lengthy race runs.
You might expect that, with the Demo 11’s high-ish pivot layout, it would produce a rearward axle path, and that’s exactly the case. Apparently, the rearward movement happens early in the travel, while moving closer to the bottom bracket later in the travel. This is to reduce rear-wheel hang-up over sharper terrain while maintaining compsure and maintaining ‘wheelbase stability’ under a lot of load.
OBB then works with the chassis to provide a ‘Self-Aligning Chassis’. It’s a tough one to explain, but the rear wheel pulls on the linkage, which then drives the shock, rather than pushing on the whole system, and no, this isn’t like Fox’s old DYAD pull shock, as the linkage is doing the work here, compressing the shock just like normal. This pulling motion then encourages better chassis alignment, says Specialized, helping the rear wheel track straight, improving predictability and composure.
Everything else is pretty normal (for a downhill bike)
Elsewhere, the Demo 11 is fairly standard. It’s constructed of Spesh’s FACT 11m carbon fibre, which has been tuned to cope with downhill punishment, and it’s loaded full of geometry adjustments. As standard, the bike offers size-specific chainstay lengths, but the user can fettle with the front centre by 6mm, fore and aft, thanks to replaceable headset hubs. The bottom bracket then offers 7mm of height adjustment through a flip chip in the linkage.
On an S4 frame, the Demo 11 offers 475mm of reach in its middle setting, a 62.5-degree head tube angle and a 445mm chainstay. The bike also runs a mixed wheel setup (29″ front, 650b rear).
There are only two Demo 11 offerings available, with the Demo 11 S-Works coming equipped with SRAM’s XX DH Transmission, SRAM Maven Ultimate brakes and the latest RockShox Boxxer and Vivid coil suspension components. On the Roval Traverse Gravity Alloy wheels are a pair of Specialized’s Cannibal tyres with downhill casings. This bike will set you back a not-so-friendly £10,499. It’s also available as a frame only for £6,499. We don’t have UK pricing at this point.
