Course of Power

Pedaling forces generated at the left-sided crank are transferred to the left sprocket of the StitesHub via the top chain.  This sprocket is directly attached to the left universal joint shaft.  The left shaft spins in a bearing supported by the main frame.

Torque is transferred across the center of the universal joint to the right shaft.  The right shaft spins in a second bearing supported by the steer tube/fork assembly.  The right StitesHub sprocket is attached to the end of this shaft.  This sprocket transfers power, via the down chain, to the front wheel.

Universal Joint

U-joints are ubiquitous in automotive technology, as well as many other fields.  They are typically used to transfer torque at a fixed angle.  Part of the novelty of the universal joint application in the StitesHub is the constant variation of the angle of deflection based on real time steering.  These angle variations do not hinder torque transfer as long as they remain within the specified tolerance - about 25 degrees in each direction. Since the Chameleon ECO leans and rides like a bicycle, the steering deviations are similar, and often within +5 or -5 degrees of turn.  Thus, the vast majority of time the u-joint is straight or only slightly flexed.

Torque can be efficiently transferred during turning as per the intended function of the universal joint.  While torque to drive the front wheel is being propagated by the rotating shaft, the u-joint flexes to accommodate rotations of the steer tube/fork assembly.

The efficiency of this mid-drive system is supported by the fact that the StitesHub behaves like a solid shaft when the u-joint is straight or nearly so.

Worm Hole

The center of the u-joint is somewhat of a StarTrekian worm hole.  It contains a precise point where power can transfer from the elements fixed to the frame [cranks, top chain, left side of StitesHub], to the mobile steering elements [right half of StitesHub, down chain, front wheel] ... with no influence on steering.

Q Lowracer

The worm hole is a magical point, that is defined by the intersection of the axis of rotation of the u-joint shaft with the axis of steer.

Notice that the u-joint is aligned directly over the center of the steer tube.  In this way, the torque propagated across the shaft is perpendicular to the steering axis ... and does not create any moment arms or other forces about the steering axis.

Again, no influence upon steering.  One can pedal hard and travel in a straight line with no steering stabilizing or dampening.  To put it another way, you can cruise with no hands on the Chameleon while jamming on the pedals.

No Chain Twist

Note also that because the right half of the StitesHub moves with the steer tube/fork, the planes of the down chain and the front wheel always remains parallel.  Therefore, there is no chain twist upon steering.

No Reaction Forces

One would expect some steering effects from the down chain pulling the cassette on one side of the wheel.  However, there is no asymmetrical chain pull upon the front wheel.  This is because the right StitesHub sprocket is supported by the steer tube ... so there are no reaction forces between this sprocket and the cassette.  The down chain is intimated into the steer tube/fork assembly, and thus cannot possibly cause forces that could induce an undesirable steering rotation.

This is an important and counterintuitive result.

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.