I have a couple of drawings which were given to me, but after much deliberation did not use them as I did not trust the dimensions.
I also did a full size tracing of a Slater Egli frame owned by a local Vincent club member. He bought the kit about 20 years ago but never assembled it. It has a 22 degree headstock angle which I did not like, in fact I'm not even sure it can work. The front wheel could hit the engine when the suspension compresses.
In the end I designed my own frame and built it around the engine. As for the upper frame, it was more or less a case of connecting the dots. The swing arm or rear frame was a real head scratcher as I wanted to improve on both original Vincent geometry and dual shock Egli geometry by adding progressive suspension to the setup, and also to make it work with a modern mono shock. Also, a big offset had to be built into the swing arm to get chain clearance with the 180 rear tire.
And the whole excercise was to drop weight while adding stiffness. This was achieved with the use of thin wall large section stainless box tubing.
The headstock angle I used is 27 degrees. Terry Prince told me that was what he and Fritz Egli chose for the original Egli-Vincents. The reason they went with that angle was that it is the same as a Norton Manx racer, a bike that has been proven again and again to have terrific handling properties.
I found this bike to be almost effortless to ride fast. On twisty mountain roads, I much prefer it to my 05 Triumph Daytona 955.
