Big-wheeled mountain bike specialist Niner Bikes is soon to release a cleverly simple new eccentric bottom bracket design for singlespeeds and a lightweight carbon fibre fork for 29-inch wheels.
Niner’s new Bio-Centric EBB steps away from traditional wedge-type or Bushnell-style eccentric designs with a two-piece clamshell layout that is far simpler in construction. The two halves are inserted into a standard eccentric bottom bracket shell from either side while a single offset bolt connecting them nominally maintains alignment between the bottom bracket cups during adjustment, secures them together and also pulls the outer flanges tightly against the ends of the shell to prevent unwanted rotation.
Niner says the simple design runs creak-free and eliminates the possibility of bottom bracket shell ovalisation caused by an overtightened conventional eccentric. Moreover, the full-circumference outer flanges supposedly seal the shell interior from contamination and the system is also lighter than usual. Compared to traditional eccentrics – which can weigh upwards of 300g (even Bushnell’s new Featherweight design is still 140g) – the Bio-Centric is just 117g including its single stainless steel bolt.
Though Niner has obviously designed its system with its own 29in mountain bike frames in mind, the Bio-Centric can also be used with similarly equipped 26in-wheeled frames or even tandems. According to Niner’s Steve Domahidy, the Bio-Centric has been thoroughly tested in the field and has also passed the grueling CEN chain torque fatigue test with no issues. Retail price is surprisingly reasonable at just US$80 (approx £55).
29in rigid fork
Niner’s pending full-carbon rigid 29in fork is still in the development phase but nearing completion with some impressive early details. According to Domahidy, the new disc-only fork is “carbon from top to bottom” including the steerer, crown, legs and even dropouts, and final weight is estimated to be in the neighbourhood of 550g.
Stainless steel faces on the forward-facing dropouts will prevent damage from serrated hub axle ends and quick-release skewers, post mount disc brake tabs will eliminate the need for most caliper adapters, and brake hose routing will be directly integrated into the left leg.
Despite the feathery weight (roughly 1.2kg lighter than most 29in suspension forks) Domahidy says the fork has “far exceeded any standard testing parameters” and the company has conducted more than six months of field testing on various prototypes (we spotted one at the 24 Hours of Moab last year).
“We’ve gone above and beyond what anybody is doing in rigid fork technology and we are really using carbon in the way it was intended,” said Domahidy. “[The] super-stiff steering precision coupled with the damping characteristics of carbon make this fork wickedly strong but still forgiving for a rigid fork. The fork blades have been designed to maximise the strength of carbon while still allowing for that damping quality that carbon is known for.” Pricing is still being finalised but Domahidy estimates it will be around US$350 (approx £245).