Fork and shock analysis

[Polux RSV]

Hi,
My bike is fitted with both potentiometers. Everything is working and I got reports in I2.
I could interpret the basics: end of fork travel on braking, balance during accel, chain effect during reaccelleration.

But I lack some advanced knoweledge. I could use some external tools, like Matlab, but don't know what to look for. Speed and frequencies ? Ok, but which values will be ok? What is the best behaviour to reach ?

Is there any books, articles or website where I can learn ?

Tanks

Angelo

[Holmz]

Hi,
My bike is fitted with both potentiometers.
...
Angelo

First - I have no idea about bikes...
So I only have some thoughts for your general entertainment.


The book by Milliken and Milliken may be worth a read http://www.millikenresearch.com/rcvd.html, and I have seen them on ebay and amazon.

What is it that you care about?
What is it that you need to understand in order to get improvements?
And what improvements are you looking for exactly?

You may care about control of the motion of the chassis and the wheeIs
I would guess that the force between the tyre and the road surface is probably one of the more important items.
As I suppose it is more of the later... Then:
1) The springs cause a linear effect on the force.
2) The damper's effect on the force is probably more linear with the velocity of the damper (assuming that there is some fixed and known behaviour). Or more likely it is a much more complex cause and effect relationship as the dampers curves are complex.

If you are good in MATLAB you could probably model the acceleration forces and moment forces (which are torques), and apply different theoretical damper curves to then plot that against the expected force between the tyre and the road.

So I see two uses for your data:
1) To get the data for the MATLAB in order to find the optimum damper dyno curves - and then get the dampers tuned to the modeled optimum values.
2) Another way would be to also have a strain gauge (say on the swing arm) to allow you to also have some idea about the force between the wheel and the road in a more direct measurement of tyre force. That may augment the data that the dampers are providing and should provide some empirical evidence as to the cause and effect relationship between the damper settings and having better or more constant tyre patch loading. So you would adjust the damper to get some best fit of tyre contact patch loading to optimise performance, by using the strain gage data.

I could see where you could get to the point where you could run through step #1 on a new track and make adjustments and then verify that you were close using step #2 - or iterating back and forth.

It looks like you are taking a pretty reasoned approach to it, and I am interested to see where you go with it.

Also I know a good mathematician who is MATLAB savvy and may be interested in helping.