[python] Re: NT, Pivot Angle, and handling question

Tim k wrote:
> Hi everyone,
>  
> I'm new to the list and trying to learn more about pythons, with the
> possibility of trying to make one sometime this summer.
>  
> Anyway, I had a question about the handling of a bike --- all things
> being equal (which I know they almost never are)  is the handling of
> the bike all about the seat rising effect?
>  
> For example, a bike with 14cm of NT and a 60 degree pivot angle has
> about the same amount of seat rise as a comparable bike with 30cm of
> NT and a 78 or so pivot angle. All things being equal (center of
> gravity, wheelbase, wheel  size, etc), would these two bikes more or
> less handle the same?
I believe the self centering AND the angle counts for the feel of the bike.

When you increase the head angle, you will have a benefit in the
maneuverability, but on the down side you'll have more pedal induced
steering (78degrees sounds very high, its nearly straight up).

But with all these different geometries, and many different opinions it
is difficult to say what is really better. It has a lot to do with what
you are used to (both non-maneuverability and pedal induced steering are
compensated largely by skill and habit).

I know two models with about the same self centering and same angle, but
with different trails and wheel sizes (I am talking about the monty
(16") and the baby python (20")). These two bikes have a slightly
different feel, but are very much exchangeable. When I try the monty, it
is only the first moment it feels different, after that it's like I've
never  ridden another python.

That a different self centering and but same angle does make a
difference showed me the experience with "Marc Python" (bigger self
centering because the trail rises from 14cm to 16cms(?) and a shorter
wheelbase (110 -> 100)). The bike felt very much different, and me being
used to my baby python, I didn't like it much. I found my bike to be
much more forgiving.

A friend of mine has a home built flevo racer (26"), and made a
contraption so he can change the head angle from 45degrees to somewhat
higher (may be 60-70degrees, the positive trail goes also down as a side
effect --so it is unfortunately not a clear experiment with head
angles). Both me and him found that the bike is *much* easier to
control. And that even though we are used to the typical 45degrees of
the flevo.
>  
> Thanks! I apologize if this has been covered before. I've been trying
> to make my way through the archive, but there's just so much
> information to go through.
Not mention it. The NT, angle, etc, and what or what is not important is
still a mystery and there is no consensus.

A lot is decided when you choose the front wheel. After that you can
tweak only a little with the NT and the angle, as you will want to have
the pivot as near to the front wheel as possible, minimizing the NT for
an certain angle (probably some will disagree with me here ;-) ). You
can then further diminish the self centering by lengthening the bike.

best regards and good luck designing your bike,
Dirk

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