Miranda Miller's Prototype Specialized 29er DH Bike - Fort William DH World Cup 2018
The Fort William downhill track is a brutal one, with a surface that looks like a cobblestone street after an earthquake. Specialized's Miranda Miller will be taking on the high speed, rock-riddled course aboard a 29”-wheeled prototype, the same bike that we first caught a glimpse of at the Whistler Bike Park last week. Loic Bruni and Finn Iles will be sticking to their 27.5” Demo races bikes, but I'm sure they'll be spending time on this yet-to-be-released machine in the near future.
The frame design is a distinct departure from the current Demo – it's no longer one-sided, and there's also no concentric bottom bracket pivot to be seen. Instead, the shock is driven by a vertical link that's attached to the seat stays and a horizontal link that's attached to the main pivot. The design keeps the shock positioned close to the bottom bracket, which should keep the bike's center of gravity nice and low.
The shock position, bottom bracket height, and chainstay length can all be adjusted on this prototype aluminum frame.
The concentric BB pivot may be gone, but it does look like an eccentric bottom bracket has been installed, although I doubt that's something that would make it into a production model. Eccentric bottom brackets are more typically used to adjust the chain tension on singlespeed bikes without horizontal dropouts, but they can also be used to adjust a bike's geometry – the BB height and chainstay length can be altered by rotating the device inside the bottom bracket shell. Miranda's bike also has what looks like a flip chip at the front shock mount. It's currently in the middle setting, but I'd be willing to be that there's a high and low option as well, at least for this particular frame.
The Fort William track hasn't been very kind to Miranda - will this be the year she gets redemption?
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but with a CS pivot. They're f*cking with us now. Asymmetric one is amazing. What's happening?
The banshee is a short-link (aka VPP) kinematic with shock operated directly by the lower linkage.
I wonder if knolly will sue them ????
1. "A Knolly simply uses an in-line extension to drive the shock between two similar links"
Not true, on Knollys (obvious on podium and v-tach, a little less on warden, endo, delirium) the shock is driven by a rocker, which is pushed by a floating link between the seatstays and the rocker, which forms a secondary quadrilateral (frame-shock rocker-floating link-upper fsr link) hence the 4-by-four name from Knolly.
Since the the "floating link" has a pivot on both ends (seatstay and shock rocker), it doesn't behave like a rigid extension of the seatstays so the amount of rotation and angular velocity of the 4-bar quadrilateral is different than the one transmitted to the shock rocker by the secondary quadrilateral. In this it is close to Evil delta system, but on a 4-bar kinematic.
That's exactly the same layup as on the new spesh, except the secondary quadrilateral is inscribed inside the fsr quadrilateral for the spesh, and outside for the Ks.
2."This design is using the seatstay to pull a link that is attached to the shock with another link attached to the frame behind the BB"
The fact that the shock is attached to the upper link has no importance. Since this member is a floating one, the shock path is driven by the lower link's arc which is in fact a rocker attached to the frame. The shock is bolted to the frame one one side, to the rocker on the other side, and the rocker bolted to the frame, too. The shock could be bolted at any place along the rocker/lower link, it's angular displacement will be the same (but not the same linear displacement of course). The angular speed gradient is given by the "floating link", still like on knollys and evil.
Who would have predicted that?
(NB I'm still on obsolete wheels).
looks like a shit !