NIne Bikes has secured a patent for its Constantly Varying Arc suspension technology (and if you want to geek out, the it’s patent No. 7,934,739). According to Niner, in addition to being designed specifically for 29ers, CVA’s advantages include efficiency across all gears, which is important with the growing usage of 2×10 drivetrains.
“The timing on this is great,” said Chris Sugai, president of Niner Bikes. “As we predicted when Niner was founded, 29 is now a significant focus in the industry. Our early commitment to this platform means that we have the only patented suspension system developed specificall around big wheels.”
CVA is designed to be efficient in all chainrings. Because of the location of the lower pivot (under the BB) chain torque effectively isolates and cancels out the forces acting to create inefficiency in pedal stroke.
Unlike some parallel link suspension designs, the CVA’s “instant center” location is in front of the drivetrain. With the lower pivot under the bottom bracket, the force at the rear axle resulting from chain tension pulls the two linkages in opposite directions in all gear choices, effectively isolating the drivetrain from the rear triangle.
Past the rearward-most position at sag, the axle path moves in towards the bike at a gradual, constantly varying arc, which insures that there is minimal chain growth throughout the length of travel. This also means minimal pedal feed back in the drivetrain while cycling the suspension, again, essentially isolating it from the fully active movement of the suspension design.
The CVA design is featured on all Niner’s full-suspension bikes.