This is just a start of the frame build. This entire project has been about using what is available first and then filling in the gaps as I need things. As a result of also imposing the one-off criteria the frame jig will be used once. So it has sort of a DIY look to it.
The bench was an old TV stand from a friend that I put wheels on. The main beam is folded steel left over from a Land Rover project and the upright was snagged at the recyclers.
So here are some numbers. The base is 3 inches in height. The rear wheel is a stock 18 inch Honda DID rim. The upright is 2 inches wide. The height from the bench to the rim gives me a starting tire sidewall of 3. So to get a feel of the placement in relation to the spine tube the distance from the back edge of the spine is about 5 5/8 inches, which should give me plenty of room for a tire side wall of up to 4 ½ inches. Of course I have to do some more checking on available tires before I commit to those dimensions.
The gear box and engine are going to be close coupled with alloy plates with the gear box adjustment for chain tension to the engine main shaft on the top. The bottom of the box will pivot on a mount point near the base of the spine tube. Well I hope. If things work out the general gear box engine ground clearance should be a bit over 3 inches.
What I’m trying to get is a fairly short and stiff rear triangle. I’m not flat tracking this so stiff in the rear hind quarters should build in less flex in a light weight frame. At the front end will be a head tube rack of from 20 to 28 degrees. From the head tube will be a down tube to a bracket which will carry the front engine plate. So the engine and the gear box bolted together will become a stressed member of the frame.
With the girder fork at the front the trail should be in the range of 31/2 to 4 inches with the 19 inch front rim and a tire side wall of from 3 to 4 1/2 inches.
We will see. There is much work, fiddling, blocking, measuring and such before tubes start getting cut and welded along with cutting alloy plate and the list goes on.