[python] Re: Self Centering vs. Wheel Flop

Hej Dirk,
i'm not the best in theoretical physics, even not a good mathematician, so let me thank you for your lessons. Be honest if you think my skills are to low to understand these things or i am just boring you with that ! 

dirk.bonne@xxxxxxx wrote:

Hi Stephan,


Stephan Schöling wrote:

Hej Dirk,

please, can you explain why you see a system with two weightpoints ?
I only see the Center of Gravity (CoG) and can´t understand why the BB
should be important.

Well it is only to model the weight of the bicycle and the weight of the
rider. Some of it is on the front part and some of it is on the rear
part.
Ok, i got that. We can measure the wight of the bike and the proportion front/rear easily. But how can we do this with a rider ? We would need 2 persons to read the scales under the wheels at _exactly_ the same time, which is nearly impossible. So we have no usable data of the weight proportions of the bike with the rider, or has anyone ? 
 It is not enough to concentrate everthing in the CoG, because the
bicycle is devided at the pivot. I proposed the CoG and the BB because
that is easiest to guess or measure how the weight is distributed.
I think i would help to reduce the system to easy static parts to examine the static basics and then put everything together to calculate the dynamic system. The frame isn't divided if you look at it as a static system in some situations from having the frameparts in line to completely "flopped". 
So you can calculate the forces while having the riders weight in CoG.
Good idea ?

Now, my way to think is to add some weight in the CoG till the frame
stabilizes.

Yes but the model is artifically, you need explicitly add a weight to
the front part otherwise there will not be any wheel flop.
You're right. Can we use the the measured weights of the riderless bike for that ? 
Then i add the riders weight minus the weight i added before for
stabilization. Now i have the weight that  produces the
Self-Centering-Force (Stabilization-Force).
If i loose weight  (e.g. loss of gravity because of a deep pothole ;-)
) i loose stabilization force. (   %  <-- sign for "python crashed" ?)

A very very deep pothole. Sounds more like a cliff to me ;-)
Oh no, but you know what i mean. With every downward movement the weight decreases, even if it is only 1 cm. It is another question to discuss the behavior of the python bike in free fall. With my motorbike i once researched that the problem isn't the flight, but the hard landing... 
I hope i am right, when i assume, that it doesn't matter where the
rider is placed and where the points are, which transfer the forces to
the frame as long as i know where the CoG is.
What is missing in my system ?

Cheers,
  Stephan

(BTW, i see us sitting in a pub discussing all that
flop/effect/force/gravity-stuff and the guys next to us wondering
about how worse things alcohol can cause ...)

who knows may be we will once? :-D


What about the idea of Jürgen (?) to meet at Spezi in Karlsruhe ?
Or let us find a nice Irish Pub, good reachable fore everyone interested ?

groetjes,
Dirk

cheers,
   Stephan
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