All bicycles and trikes are articulated at the fork. This allows the fork to move in one degree of freedom, rotation about the steer axis. This provides for steering of the vehicle.

The Chameleon concept may be described as "double articulated". In addition to the fork articulation, there is an articulation to allow leaning. The front sub-frame [orange] supports the seat, and is the leaning portion. The rear sub-frame [black] does not lean, maintaining the two rear wheels on the ground.

The axis for the lean articulation is at the center of the rear top tube [black]. It runs parallel to the ground, and along the long axis of the vehicle.

The lean articulation is comprised of two pivots. The aluminum pivots clamp onto the square top tube [orange] of the front sub-frame. They also lightly clamp onto the rear top tube [black], about which they pivot.

Delrin acetal plastic bushings are interposed between the aluminum pivots and two Stainless Steel surfaces on the rear top tube [silver on black]. This bushing arrangement provides for a smooth and predictable glide. Friction is adjustable by tightening or loosening the lower bolt of each pivot.

Elsewhere in this website, the two pivots are referred to as "front articulation" and "rear articulation".

The handlebars are mounted within the rear sub-frame [black], and are thus part of the non-leaning portion.

Leaning is controlled by applying vertical forces into the handlebar. This induces rotation of the front sub-frame about the horizontal axis of lean. Since the rider is seated and pedalling upon the front sub-frame, the body weight is shifted to the inside of a turn for balanced cornering.

So-called Lean-Steer vehicles must have an angled, i.e. non-horizontal, axis of lean. This is required in order to impart some turn of the front wheel for steering.  In these vehicles, the proportion of lean-to-steer is fixed: for every X degrees of lean, there is Y degrees of steer.  This becomes undesirable and dangerous when cornering outside the limited prescribed speed ranges for these vehicles.

The axis of lean in the Chameleon is horizontal.  This is an important distinction as leaning does not impart any steering effect.  Steering is achieved by the fact that the front wheel is independently steerable within the front sub-frame.

In this way, the rider's brain can control lean and steer independently for optimum balance and dynamics ... just like on a bicycle.

Time Rollback ... circa 1997-98

Bill Stites carving a hairpin turn on the original Chameleon

Steering is controlled by applying horizontal to-and-fro forces into the same handlebar. This pushes and pulls the steering rod and induces turning of the front wheel.

Yes, leaning and steering are independently controlled through the same handlebar. Your brain's ability to seamlessly combine these controls for smooth bicycle-like riding is the secret to this trike's success.

This is one of the most outstanding elements of the Chameleon design.

Although the seat is located above the rear sub-frame, it is mounted to the front sub-frame via the square top tube [orange]. Since the seat is fixed with the leaning front sub-frame, the rider's body 'becomes one' with the front sub-frame.  The rider remains vertically balanced over the front wheel in all riding maneuvers ... just like a bicycle.

Lean Lock

Rear close-up view of Lean Lock plate.

Quick release lever to lock down.

"Radial Arc" refers to the new type of suspension afforded by the lean articulation.

Lean lock quick release lever [black] fixes square top tube of front sub-frame to a Stainless Steel plate on the rear sub-frame. This achieves lockout of the lean capabilities.

Tab at rear end of front bottom tube [orange] is bolted into bottom of rear articulation.

Square top tube [orange] provides for seat mounting.

The articulated frame provides an important new additional benefit - we call it 'Radial Arc Suspension'.
The purpose of suspension is to provide relative movement between the wheels and the frame so that irregular road surfaces can be comfortably accommodated. Most suspension systems utilize springs or cylinders to allow some vertical motion of individual wheels. Control and balance are maintained by keeping all wheels in contact with the ground.

Radial Arc Suspension is new and non-traditional in that it utilizes a suspension axis that is parallel to the ground, and runs along the long axis of the trike. The frame parts rotate radially about each other, providing relative wheel movement. Traditional suspension moves the wheels along a suspension axis that is roughly perpendicular to the ground.

Heavy front vs. Light rear

The goal during riding is to maintain balance of the front sub-frame as it contains most of the 'essence', i.e. the rider mass, the drive system, the steered wheel.

The bulk of the rider mass is with the front sub-frame, since it contains the seat and cranks. The rear sub-frame is relatively light and well controlled by the rider through vertical manipulations of the handlebars. The fact that the handlebars are mounted in the rear sub-frame provides the rider with tremendous control of the overall orientation of the vehicle.

The simple rear sub-frame is, in a way, subservient ... it exists to assist the front sub-frame in maintaining stable motion, especially balance.

The handlebars and the rear wheel axle always remain parallel.  Thus, a rider learns to feel the height of the rear wheels through the handlebars.  This provides excellent feedback of the vehicle's orientation.  The rider is then able to input compensatory forces as the vehicle moves over irregular surfaces.  

It is an active suspension with the world's most powerful controller - the human brain.

The goal of balance and verticality in the front sub-frame is readily achievable with little effort.

An extreme example is shown with one rear wheel up on a curb, but with a balanced and vertical front sub-frame.

This capability was present even in the first Chameleon.

As noted earlier on the 'Chameleon' page,

In Summary

This design achieves full independence of its three [3] main systems:

Drive - pedaling the FWD system causes no effects to steering nor leaning.

Steer - steering the front wheel causes no effects to driving nor leaning.

Lean - leaning the front sub-frame causes no effects to driving nor steering.

This represents the keystone of the Chameleon design.