[python] Re: max downhill speed --lost mail, second try

  • From: Dirk Bonne <dirk_bonne@xxxxxxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Wed, 11 May 2005 10:14:31 +0200

Daryl Bender wrote:

> I haven't ridden a Python yet so anything I say is most likely crap
> but wouldn't the wheel wander at low speed if you weren't on the
> bike but just pushing it (no weight on the pivot)? I would think that
> within reason loading the pivot - weight, ground
> effects, whatever, would tend to *try* to keep the wheel straight.

yes. even more so, without the weight of the driver the bike colapses
and is really unwilling. It is first when sitting on it the bike
straightens up, and transforms from just being junk to junk that rides.
May be the name python comes from the fact that it tends to be coiled up
like a snake when left by itself :-\

> The problem I see is that given that speed forces generally happen as
> the square of speed I could also see that this linear approach may get
> you some extra KPH but the inevitable will soon "rear it's head" again
> at a somewhat higher speed. The square forces overpower the unity
> forces no matter how big they initially are and eventually force the
> "shopping cart caster" into its otherwise stable position.

yes, and would like a way to push the problem (whatever it is) out of a
reasonable speed range :-D

> Take rolling resistance (varies with v**2.5). If your front wheel gets
> even slightly off straight isn't that like a front brake applied with
> your wheel turned forcing the bike to want to fold up?

I have only a front brake. I never experienced a problem with it. I have
not found any tendency until now that wanted to collaps the bike. I know
I talked about cart wheels in that video of olaf. But may be I should
have shut up there, because I cannot align it with my experiences:

About a month ago I had an car accident. The car came from the direction
opposite to me and pulled up to his left crossing my pathway. The driver
did not see me coming (I was riding mountain down, sundown in the rear).
So the car came accros my pathway, and I was riding fast. That was
exactly a manouver with hard braking with sharp turning combined. An
ideal opportunity to (1) collapse the bike and (2) get killed.

But the bike did not fail me.

I still slammed into the car, but I managed to turn so far that we hit
side by side, and got away with nothing more that a pair of jelly legs

After that I became a believer ;-)

> I'm guessing we need to pull a correcting "cube" out of our panniers :-D



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