MJPriceisright said:
great post, very informative. thank you.. yeah your right when it simply comes down to riding style. those stock footrest hangers have some thickness to them, not quite sure what im going to do about those just yet.
MJ - I started the final strip of the donor bike yesterday and had a good look at the area in question.
Without question the whole assembly is tied in one to the other. Footrests [ via engine cases ], to seat frame, to main frame.
The footrest hangers are far more substantial than required for just hanging the footrests - have you felt the weight of them ! They are bolted securely to the cases and then there is another substantial chunk - the seat support frame. This acts as a girdle around the cases [ via the footrest hangers ] and then is bolted directly back to the main frame. Take ANY one part out of the equation and it makes for a far less substantial structure.
In my very early days as a design engineer I was taught by a very respected tutor to exagerate ALL forces and stresses to see what the outcome could be - then dilute the findings down to the working level. A sort of safety factor if you like, but exagerating the design allowed you to easily see the "what ifs" and show up any marginal design.
The frame IS fuggin uggerly, no question. In my aplication - no problem as I will have side panels inkeeping with a 60's look. IF I were looking at an alternate for a modern take on a Cafe Racer [ and I did at one time] I think I'd go for a Duke style trellis frame.
I even went so far as to look at the frame on a spare BMW K1100 with relevant forks, 4 pot Brembos etc.
I'll take some pix of the area in question in the next few days - food for thought.
Would the cut down system fail ? Probably not. Would it put additional strain on the integrity of the engine cases - undoubtedly.