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Vasttech Suspension System
Superior pedaling kinematics, more efficient bump absorption, massively reduced un-sprung mass, with reduced complexity and the lightest frame weight.
Superior Pedaling Efficiency
Greater chain pull force where you need it and zero chain growth where you don’t. More chain pull force to resist pedal bob in the pedaling zone of 20-35% sag provides more direct acceleration and keeps the rear end from squatting on steep climbs and sprints. Zero chain pull in the big hit zone through to bottom out keeps chain growth and the associated pedal kick-back to an absolute minimum. For comparison, at 25% sag the Vasttech bike pictured has 38.7% more chain growth and related anti-squat than comparable linkage driven single pivot designs. Yet its total chain growth which leads to unwanted pedal kick-back is just 13.79mm from rest to full bottom out.
A comparable linkage driven single pivot design of equal travel and identical geometry with its main pivot point 66mm above the bottom bracket, has 17.46mm of chain growth. For the Vasttech design it’s a 21% reduction of pedal kickback for every large impact encountered. The reduced overall chain growth has huge benefits to suspension performance, allowing the suspension to perform unhindered by the mass of the riders’ legs and the bikes crankset. The superior pedaling kinematics and suspension action are achieved by a rear axle travel path that is more rearward than is conventionally achievable at the beginning of stroke and through the pedaling zone.
After the pedaling zone is passed the axle path becomes vertical and then slightly forward through to bottom-out. In this way chain growth ceases in the zone of big impacts.
Bump Absorption / Axle Travel Path
The rear axle travel path has a huge influence on a bike’s ability to absorb square edge bumps. The term ‘Squared Edged’ describes bumps and obstacles encountered where the point of impact on the tyre is some way above nominal ground level. In technical terms the vector of the force exerted on the wheel is perpendicular to the tangent of the point of impact on the tyre. What matters to you and I is that the vector of force directed on the rear wheel is always rearward and upward, and never purely vertical. A suspension system that’s able to move the rear wheel in a manner most closely matching the vector of the force applied by the obstacle will be the most efficient. This increase in efficiency leads to greater control and less loss of forward momentum every time a square edged bump is encountered.
Reduced Un-Sprung Mass
The effects of reducing un-sprung mass are well documented. Un-sprung mass refers to the parts of the bike insulated from the mainframe and rider by the shock. Reducing the mass of these parts reduces their inertia and reluctance to change location, to vertically accelerate up and over the bump. ‘Halve the un-sprung mass and you halve the amount of forward momentum lost every time you encounter a bump’. The un-sprung mass of the Vasttech frame members is less than half that of its closest competitor. The effect felt when riding is immediately obvious. Far greater sensitivity to small bumps, and greatly enhanced plushness and speed over all types of terrain.
Reduced Weight and Greater Simplicity
The Vasttech suspension system allows for a double diamond frame shape for the best possible triangulation of forces with the lowest frame weight. No extra frame reinforcing is required to combat vector changing forces induced by rocker links. Two full size water bottles and a tool kit can be stored within the front triangle, out of the way of flying mud and debris, without compromising the tube shapes of the frame. There are no weight inducing bends in the downtube and no compromising shock length and stroke by using a tiny shock. This is possible even for small sized frames. The Vasttech suspension bike pictured has a shock leverage ratio of 2.2:1, lower than most comparable designs.
The low shock leverage ratio reduces pressure on the seals of the shock and makes for a smoother and more controlled suspension action. Favorable shock leverage curves are obtainable without the need for complex and weighty linkages. A reduction in the number of pivot points allows for a significant reduction in weight and maintenance. Less moving parts means less parts to break or wear out, and the associated expense of repairs.
Some rider quotes after riding the Vasttech Suspension bike:
