Sunday, January 2, 2011

What was & what's next........the story so far

So first comes the forkless steering proof of concept prototype. The image on the left shows the basic idea: take a steel frame (in this case an old Raleigh MTB) and weld on an extension to mount the forkless steering. Originally I had scrounged up some 1.75" tubing from a child's swing set. However Curtis pointed out that mitering the tubing accurately, especially with our $40 Harbor Freight tube notcher, would be extremely difficult so we sprung for some 16ga, 1"x2" steel tubing. The rectangular section will be a lot easier to cut, weld & fixture. It's probably overkill for our needs but it's better to overbuild than have the thing fold on the first test ride. One challenge will be welding the stout rectangular tube to the relatively light gauge down tube.

In preparation for all this we created 'frankenjig' to secure the frame. With a lot of tweaking and applying of spirit levels we can achieve pretty good alignment (or at least good enough for our purposes). The process of building the jig was a lot of fun and we now realize that we could have created something much simpler. The collision of concept and reality is always illuminating. Before this project Jeff & I had never worked on anything together so it was gratifying to see the level of synergy and cohesion in our collective efforts. As I start to learn the layout of the shop and discover where everything is kept this will only get better.

The next stage is to cut, prepare and fixture the rectangular tube and the components needed for the steering mechanism. The steering will require some head scratching. I understand the principle of how this works but I imagine reality will intrude and require some changes. One of the features I have incorporated is the ability to change the 'head angle'. My feeling is that the steering geometry should work just like a conventional bicycle steering where the interplay of head angle, fork offset and the resulting trail should be broadly equivalent but that is just a notion uninformed by experience. The ability to alter one of these parameters will allow for some experimenting without having to grind and weld. The other concern I have is the do with the fact that steering to the right will not feel the same as turning to the left as the plane of the wheel is offset to the right of the head tube. I have no idea if this will be a factor or not. All is yet to be discovered........

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