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Design
Designing a
state-of-the-art, lightweight,
4
wheel, off-road human powered machine is extremely
challenging. Hundreds of design hours have gone into the
Mountain Quad in such areas as the frame, suspension, steering,
driveline, brakes, ergonomics, and ease of transportation and
storage. As a result, several of the unique features have US
patents pending.
To keep the Mountain Quad as light as possible, the frame, rear axle assembly and all other major components are made from high strength, fully heat-treated aluminum alloy. The frame is powder coated which offers a tough and durable finish in many exciting colors. Bright anodizing is used as protection on most of the other aluminum components; except for potential high wear areas where hard anodizing is applied. Only one frame size is required since the cranks are mounted on a telescoping boom with 11" of micro adjustment. The handlebar fore and aft reach is easily altered using a quick release lever. With these simple adjustments, the Mountain Quad can accommodate riders from 5' to 6' 6" tall. This attention to detail results in a total weight of only 58 pounds for the Mountain Quad.
In order to achieve a good balance between traction and handling, proper weight distribution is important. On a 4-wheeled vehicle this meant we had to position the riders weight between the front and rear wheels correctly. In doing so, it was apparent that the rider’s feet and legs would occupy the very space needed for the front suspension. The only way around this was to move the suspension out to the wheels. Action-Tec has been in the business of making superior telescopic head tube suspensions longer than anyone. After talking with Action-Tec, we decided that this front suspension system would be the perfect design for providing enough suspension travel while at the same time freeing up space for the riders’ legs.
With the front suspension system defined, the next step was to work out the steering geometry of the front wheels. Steering, braking, and bump control are all-important considerations. Full Ackermann steering geometry eliminates tire scrubbing while turning, which is very important in a human powered vehicle. The next essential feature was torque-aligning steering for the situation where a single front wheel is braking on gravel while the other front wheel is braking on pavement. If done incorrectly, this can cause the vehicle to "pull" towards the side that has greater traction. We designed the geometry to maintain straight-ahead control with minimum corrective steering on the part of the rider. Bump control is also important so that the steering system doesn't send a sudden jolt to the riders’ hands. The Mountain Quad steering geometry maintains just the right level of feedback to the rider for proper "feel" of the terrain.
The rear suspension took on a completely new challenge. The goal was to get maximum traction and stability, without giving up maneuverability. A solid rear axle was chosen for simplicity. Since this cycle is more like a car than a bicycle, the design for the kinematics of the rear suspension relies on experiences gained in racing technology. Jon Nichols has designed numerous suspension systems for various race cars and trucks even before his career in the automotive industry. With this understanding of vehicle behavior, he set out to define a rear suspension that exhibited all of the necessary characteristics for the Mountain Quad. Thus the rear suspension has been named “NicholsLink Suspension System”.
Some of the important aspects of the rear suspension are not readily apparent to the rider (the mark of good suspension design). For instance, under hard braking the rear suspension will actually maintain its position so the rider won't pitch forward in the seat (anti-lift). At the same time it remains supple for absorbing bumps. Another aspect of the rear suspension is how it steers the vehicle in a corner. Most people think the front wheels are the only part of the vehicle that steer, in reality all 4 wheels are responsible for safely negotiating a corner. The higher the speed, the more critical the rear suspension geometry becomes. On the Mountain Quad, the rear suspension is designed to give understeer while cornering. This creates a stable and comfortable feeling for the rider, especially at high speed. The rear suspension is also designed to counter act the force of acceleration while pedaling (anti-squat). This keeps the Mountain Quad level without the pogo stick feeling each time the pedals are pushed hard.
Another design goal was to have a highly efficient, fully sealed transmission controlled by a single twist shifter that allowed the rider to shift under load or while standing still. The 14 speed, mid-frame mounted, Rohloff Speedhub meets those requirements with the ability to offer a wide gear range and superior torque capability without a huge weight penalty or the need for derailleurs. The final drive is accomplished through a chain driven positive traction rear drive unit. Under straight ahead driving conditions the posi-drive unit transmits torque to both rear wheels equally for optimum traction. Under coasting conditions the posi-drive unit has individual freewheels which allows each rear tire to rotate independently of each other. With 20 inch wheels, the standard gearing ranges from 13.8 through 73 gear inches (1.1 through 5.8 meters/crank rev). The optional Schlumpf Speed Drive crank increases the gearing range to 13.8 through 120 gear inches (1.1 through 9.5 meters/crank rev). Other gearing and 24" wheel options are available.
The Mountain Quad uses 4-wheel, full hydraulic disc brakes with twin piston calipers. Two separate brake levers, one for the front brakes and one for the rear brakes, allow the rider to optimize braking based on the riding conditions.
A great looking carbon fiber bucket seat shell provides excellent lateral support while allowing the upper body freedom to lean into corners. The raised front portion of the bucket seat shell prevents the rider from sliding down in the seat in rough terrain. A built in relief rib eliminates uncomfortable pressure on the tail bone region. The reversible seat cushion is made from practically indestructible material and is removable for washing. The adjustable lumbar cushion offers added comfort on those long rides. The seat uses quick nuts for easy removal and is mounted to the frame using rubber isolators to help soak up the bumps.
For easy transporting and storage, the handlebars fold and all four 20” wheels and seat are quickly removable without the need of any tools. The entire process takes less than one minute.
To keep the Mountain Quad as light as possible, the frame, rear axle assembly and all other major components are made from high strength, fully heat-treated aluminum alloy. The frame is powder coated which offers a tough and durable finish in many exciting colors. Bright anodizing is used as protection on most of the other aluminum components; except for potential high wear areas where hard anodizing is applied. Only one frame size is required since the cranks are mounted on a telescoping boom with 11" of micro adjustment. The handlebar fore and aft reach is easily altered using a quick release lever. With these simple adjustments, the Mountain Quad can accommodate riders from 5' to 6' 6" tall. This attention to detail results in a total weight of only 58 pounds for the Mountain Quad.
In order to achieve a good balance between traction and handling, proper weight distribution is important. On a 4-wheeled vehicle this meant we had to position the riders weight between the front and rear wheels correctly. In doing so, it was apparent that the rider’s feet and legs would occupy the very space needed for the front suspension. The only way around this was to move the suspension out to the wheels. Action-Tec has been in the business of making superior telescopic head tube suspensions longer than anyone. After talking with Action-Tec, we decided that this front suspension system would be the perfect design for providing enough suspension travel while at the same time freeing up space for the riders’ legs.
With the front suspension system defined, the next step was to work out the steering geometry of the front wheels. Steering, braking, and bump control are all-important considerations. Full Ackermann steering geometry eliminates tire scrubbing while turning, which is very important in a human powered vehicle. The next essential feature was torque-aligning steering for the situation where a single front wheel is braking on gravel while the other front wheel is braking on pavement. If done incorrectly, this can cause the vehicle to "pull" towards the side that has greater traction. We designed the geometry to maintain straight-ahead control with minimum corrective steering on the part of the rider. Bump control is also important so that the steering system doesn't send a sudden jolt to the riders’ hands. The Mountain Quad steering geometry maintains just the right level of feedback to the rider for proper "feel" of the terrain.
The rear suspension took on a completely new challenge. The goal was to get maximum traction and stability, without giving up maneuverability. A solid rear axle was chosen for simplicity. Since this cycle is more like a car than a bicycle, the design for the kinematics of the rear suspension relies on experiences gained in racing technology. Jon Nichols has designed numerous suspension systems for various race cars and trucks even before his career in the automotive industry. With this understanding of vehicle behavior, he set out to define a rear suspension that exhibited all of the necessary characteristics for the Mountain Quad. Thus the rear suspension has been named “NicholsLink Suspension System”.
Some of the important aspects of the rear suspension are not readily apparent to the rider (the mark of good suspension design). For instance, under hard braking the rear suspension will actually maintain its position so the rider won't pitch forward in the seat (anti-lift). At the same time it remains supple for absorbing bumps. Another aspect of the rear suspension is how it steers the vehicle in a corner. Most people think the front wheels are the only part of the vehicle that steer, in reality all 4 wheels are responsible for safely negotiating a corner. The higher the speed, the more critical the rear suspension geometry becomes. On the Mountain Quad, the rear suspension is designed to give understeer while cornering. This creates a stable and comfortable feeling for the rider, especially at high speed. The rear suspension is also designed to counter act the force of acceleration while pedaling (anti-squat). This keeps the Mountain Quad level without the pogo stick feeling each time the pedals are pushed hard.
Another design goal was to have a highly efficient, fully sealed transmission controlled by a single twist shifter that allowed the rider to shift under load or while standing still. The 14 speed, mid-frame mounted, Rohloff Speedhub meets those requirements with the ability to offer a wide gear range and superior torque capability without a huge weight penalty or the need for derailleurs. The final drive is accomplished through a chain driven positive traction rear drive unit. Under straight ahead driving conditions the posi-drive unit transmits torque to both rear wheels equally for optimum traction. Under coasting conditions the posi-drive unit has individual freewheels which allows each rear tire to rotate independently of each other. With 20 inch wheels, the standard gearing ranges from 13.8 through 73 gear inches (1.1 through 5.8 meters/crank rev). The optional Schlumpf Speed Drive crank increases the gearing range to 13.8 through 120 gear inches (1.1 through 9.5 meters/crank rev). Other gearing and 24" wheel options are available.
The Mountain Quad uses 4-wheel, full hydraulic disc brakes with twin piston calipers. Two separate brake levers, one for the front brakes and one for the rear brakes, allow the rider to optimize braking based on the riding conditions.
A great looking carbon fiber bucket seat shell provides excellent lateral support while allowing the upper body freedom to lean into corners. The raised front portion of the bucket seat shell prevents the rider from sliding down in the seat in rough terrain. A built in relief rib eliminates uncomfortable pressure on the tail bone region. The reversible seat cushion is made from practically indestructible material and is removable for washing. The adjustable lumbar cushion offers added comfort on those long rides. The seat uses quick nuts for easy removal and is mounted to the frame using rubber isolators to help soak up the bumps.
For easy transporting and storage, the handlebars fold and all four 20” wheels and seat are quickly removable without the need of any tools. The entire process takes less than one minute.