Tuesday, 9 March 2010
Picture sourced from www.hubpages.com
With the new found access to laser cutting I've been racking the ol' grey matter to try and come up with an application to exploit the possibilities. I am thinking now about making a set of girders, possibly for the A7, maybe the Chicaralike project.
There's certainly a hell of a lot to consider with regards geometry, materials and strength.
I am looking to build something around 24" in total length, probably out of 16mm (5/8")tube with a single spring/shock unit.
There are a few dimensions that do seem to be pretty much set in stone when it comes to front end design. Consensus seems to have it, that a road bike needs between 110 and 140 mm of trail to be stable and usable. The shorter the trail the "quicker" and more responsive the steering is, at the cost of straight line stability. At the moment this is an academic exercise and a working dimension of 125mm has been chosen. Another critical dimension seems to be the length of the active links, again much wiser people than yours truly seem to feel a length of 100 to 110 mm is the optimum. Also to maintain a smooth and even action through the arc of movement all four links must be exactly equal in length. A look at the picture above shows that uneven lengths top and bottom would cause the wheel spindle to prescribe an almost circular path as the suspension moved through it's stroke. Least ways, I think it would.
There's certainly some thinking to do here, but I find it pleasurable to have something to work through in my mind during those quiet moments........... to be continued
Back number plate bracket drawing was taken 'round the corner today for cutting, hope to see the results tomorrow.