Originally Posted By: Shannow
You do good work.
A frame carved out of billet would be awesome
Thanks... an carved from billet frame would be awesome but
unfortunately it would be stiff as marble and lack feel... the trick
is design a degree of tune flex quality to the chassis employing
billet and extruded aluminum pieces... allow me to elaborate because I
know this all sounds alien to someone use to 4 wheels...
In the 1980 as tires improved and engine outputs increased, the forces
involved in braking and accelerating started to overwhelm the old
flexy steel chassis and so frame builders started to make their new
aluminum frames stiffer and stiffer thinking there was no limit to the
degree of stiffness a rider could handle... thats why some riders
prefer the stiff as marble feel of the RC30 chassis but it comes at a
cost of nervousness...
In the 1990s the chassis builders started to encounter the oppostie
problem of flex as their frames got stiffer and stiffer, the bike
started chattering and vibrating, making handling terrible, especially
when leaned over, when the suspension of a bike ceases to work, being
in the wrong plane. And so the concept of flex was introduced, adding
sufficient flexibility to allow the bike to absorb some of the bumps
while leaned over, but still stiff enough to keep the chassis stable
in a straight line and under braking. Since the late 1990s, and
especially since the four-stroke era began, a huge amount of work has
gone into engineering in exactly enough flexibility in specific areas,
while retaining the stiffness in the planes where it is needed.
As tuneable flexibility has become increasingly important, the
attractiveness of alternatives to aluminium has also grown.
Traditional aluminium has the benefit of being light and easy to work
with, but as chassis designers push the limits, they also run into a
few limitations. Engineering in flex is a matter of designing chassis
elements with a specific thickness and shape, but the underlying
properties of aluminium mean that at some point, achieving the precise
amount of flexibility required means sacrifices strength. The way to
get around this problem is to by making elements longer, allowing a
mass (usually, the mass of the engine) to use the greater leverage
provided by a longer element (such as an engine spar connecting the
engine to the main chassis beam) to provide the flexibility without
sacrificing rigidity. The RC45 got the benefit of this latest
engineering in tune flex which is why it still feels modern...
1988 RC30 Short ridged front engine mounts
1994 RC45 long flexible front engine mounts
2015 RC213VS long flexible front engine mounts... The goal of tuned chassis flex is very much in evidence in MotoGp today...