DRIVE -- TILT -- STEERING
Using blue cardboard to simulate a bicycle path, I will attempt to show how the drive and tilt impact the steering.
For the majority of my riding time, while pedaling along straight sections of a pathway, I simply hold the tilt levers to keep the the vehicle in a substantially upright position. No manual ( thumb ) steering input is required. The tilt mechanisms function like a variable lean-lock device which I can adjust to accommodate variations in road surface and slope.
Although It's not observable to me while I'm pedaling forward, I'm aware that the forward rotating front wheels are constantly and freely adjusting ( castering ) to my tilt control inputs which keep the vehicle steered along the straight and narrow.
I try to illustrate this in the following two videos,First I pedal slowly forward in a straight line while holding the tilt levers stationary. In the second video I put both feet down and push to coast backwards in a straight line. No steer inputs are made in either direction.
Well, I actually put my feet down and push twice in the next video.
When entering a bend in the pathway or a sharp corner I increase the tilt just enough to free-to-caster around the bend or corner at my current speed. Again, manual ( thumb ) steer inputs are not required.
In the next video I try to demonstrate the F to C steering action while slowly negotiating a curve to my right. I start by first tilting the vehicle from side to side to indicate that controlled tilting (without manual steer input) will be used.
When I tilt the stationary vehicle there is no change in the steer angle, but as I pedal forward and actuate the seat and levers to tilt the vehicle, the forward rotating front wheels change their steer angle in response to the controlled tilting of their steering axis to follow the curve in the pathway. Although F to C operates at this slow speed, it works much better when accelerating from a stop into higher speeds where it performs smoothly and predictably (always the correct steer angle for the tilt and speed of the vehicle). A bonus is, that actuating the tilt control mechanisms becomes easier with increased speeds as the dynamic forces kick in.
Riding this prototype is quite basic. Unlike the engage/disengage requirement of most steer-tilt- control vehicles, this prototype does not require transitioning from manual to caster and back to manual steering at a certain speed threshold, and there is no obligation to think about the technique of steer/counter steer. I simply control vehicle tilt at all times and rely on free-to-caster steering to get me around the bends, corners and straight sections as F to C operates from full stop to full speed and back to full stop.
Since assembling this prototype and riding it within my neighbourhood, I have found that that manual steering is rarely needed. And when it is used, I just hold the vehicle in a substantially upright position and engage the thumb levers for steering.
In the next video I demonstrate this approach on a curve to my left. I begin by reaching for the tilt levers and press the thumb levers to show what I do to alter the steer angle of the front wheels when riding. I then pedal slowly forward, holding the tilt levers stationary to maintain the vehicle's upright posture and apply steer inputs with the thumb levers. I then maneuver backwards using thumb steering
Operationally, this vehicle is a lot simpler than my previous ones. As shown in the above video, when I'm thumb steering, I'm not tilting. And, as shown in the one before, when I'm tilting, I don't have to steer.
Although I have not yet tested this prototype in all riding situations, I'm satisfied with how it performs so far. But, I'm a little disappointed with its weight. I had hoped that removing the hand cranking drive train and building a lighter two-part mainframe would have reduced the original weight of 36 Kg by more than the 3.7 Kg I succeeded in shedding.
And, although I have constantly looked for ways, I haven't been able to significantly reduce the number of components or their complexity, except for the delta model, which has one less front wheel and spindle, three fewer swingarms, a simplified steering knuckle, and a less intricate nosecone.
I look forward to your replies- especially any suggestions on how I might be able to simplify any of the components.