During my reading of Tony Foale's book (titled "Motorcycle Handling and Chassis Design"), the connection between the head tube and the frame was clearly identified as being a weak spot in almost all frame designs, and he overcame this weakness using full triangulation. If you have access to the book, it's chapter 10. I'm not quite sure this applies to bicycles in general, but given I'm using front-wheel drive ....
So when I first pictured
the design of my bike, I envisaged using full triangulation similar in principle to his designs, and allowed for the extra height of the triangulation by raising the top tube of the frame to give it it's unique look. This also allowed quite a large area below it for mounting the batteries. The battery housing would take the form of a big "V", mounted in such a way as to give the appearance of being a structural member ÃƒÂ la Ducati.
The triangulation would also appear to be a "tank" as seen on a motorcycle, and I decided I would utilise the space for the controller and other wiring once enclosed.
So, once all the work on the front forks had been completed, this remaining weak spot was tackled. I ordered several metres of 14 mm tube from the local steel supplier, and after 17 days, 1/2" tube finally rolled up
. In the overall scheme of things the different diameter was neither here nor there, and so working from the rear of the frame to the front I tack welded, heated and bent this tubing to fit. Where a dramatic change in angle was required, a short piece of 1/2" tube was tacked in position to the top tube before the longer tube was heated and bent. Once the left-hand side had been completed, I started on the right-hand side. That's when I remembered to take a photo
After completing this part, I realised I hadn't left enough room to mount the rear brake caliper and to make matters worse, there wasn't enough clearance for the chain to fit on the 11T rear sprocket. Missed by this much : index finger and thumb held slightly apart :
Oh well, I'll fix for next discussion
Still to do on this is fully welded all joins, attach two crossmembers at the base of the triangulation, and add a tab at each corner of each triangle to attach the bodywork to. Originally, it was going to be either fibreglass or wire meshing, but now it will be very thin sheet aluminium which will either be painted matte black or anodised black (if I can figure out how to do anodising - I know there's a link on AJ's build somewhere).