Hi Stevens,
Pivot angles in the 60s help bike / tilting trike stays up right. As I got
better I found lower pivot angles less nervous (smoother) even on a bike at
moderate speed.
Vi
On Apr 27, 2020, at 10:29 PM, Howard Stevens <hstevens94@xxxxxxxxx> wrote:
I am interested in the pivot angles mentioned. Paul says he uses 56 degrees.
I have made a few trikes and found that I needed a pivot angle of around 55
degrees and not the 62 degrees sweet spot that the Python bikes use. I
suspect that it has to do with weight distribution being different in trikes
and bikes. Howard Stevens
On Tue, Apr 28, 2020 at 3:06 PM FreeLists Mailing List Manager
<ecartis@xxxxxxxxxxxxx> wrote:
python Digest Mon, 27 Apr 2020 Volume: 18 Issue: 008
In This Issue:
[python] Re: Strange behaviour Python trike
----------------------------------------------------------------------
Subject: [python] Re: Strange behaviour Python trike
From: paul needham <paul.2.needham@xxxxxxxxx>
Date: Mon, 27 Apr 2020 21:52:09 +0100
Hi all
Trike shortened by about 30cm and rides much better , thanks for your help.
It probably does not help also that I am 72kg and the pilot of the
problem Python is probably closer to 90kg !
The build is here :-
https://atomiczombie.com/forum/threads/dannys-daily-delta.26/ Dannys ;
daily delta <https://atomiczombie.com/forum/threads/dannys-daily-delta.26/>
An attempt to convert a unsuccessful MBB delta trike into a Python.
regards Paul
On 25/04/2020 20:19, mircosoft@xxxxxxxxxx wrote:
Hi Paul,
If the trike steers uphill, it means its steering pivot gets pulled
downhill by the resulting weight forces acting on it. Uphill steer can be
minimized by moving the rear axle further forward, adding mass behind it,
moving front wheel closer to steering pivot or adding mass in front of it.
I think the last point is the easiest to achieve: all the rider needs to
do is to put his feet back on the pedals. Python's geometry counts on
their mass being there and acts funny if it isn't.
As to the pivot angle effect, I think we can't make any conclusions
without seeing the trike. There are many torques involved and they are not
all directly proportional to the angle.
Regards
Mirek
On April 25, 2020 5:00:33 PM GMT+02:00, Patrick van Gompel
<patrick_van_gompel@xxxxxxxxxxx> wrote:
Hello Paul,============================================================
Not sure if I fully understand, but isn't this a common effect on
non-leaning trikes?
I think it depends on where the Center of Gravity is, but if that point
wants to go down (down the slope). Wouldn't that mean that your trike
wants to go up (up the slope)?
Or am I thinking to simplistic here?
Patrick
________________________________
Van: python-bounce@xxxxxxxxxxxxx <python-bounce@xxxxxxxxxxxxx> namens
Paul Needham <paul.2.needham@xxxxxxxxx>
Verzonden: zaterdag 25 april 2020 16:42
Aan: python@xxxxxxxxxxxxx <python@xxxxxxxxxxxxx>
Onderwerp: [python] Strange behaviour Python trike
Hi all
My trike is a success and does about 1600 km a year.
A friend wanted to try and build one as well , however his has strange
behaviour ? he lives over 4 hours drive away and under the current
circumstances I cannot visit to try it for my self.
He has the ability to change the pivot angle about 10' either side of
the 60' he started with , mine is 56'.
These are his comments :
I have tried a few more simple runs up and down this lower end of my
street. I have taken the opportunity to coast “feet off” in all runs.
I have also taken the trike into the car park yard of the BT exchange
where there is no camber as such but the surface is sloped.
I have the following observations to impart:
1. If there is a slope or camber to the road the front end wants
to go UP the slope (towards the centre of the road).
2. The angle of the pivot magnifies this effect. More vertical
pivot = LESS turning force; more laid-back pivot = MORE turning force.
3. Trying this same coasting with feet off trick travelling in
the wrong direction up/down the road on the wrong side of the road the
Left/Right turn is reversed, the front end still wants to climb the
camber/slope.
This rather suggests to me that it is the fluidity and “relative lack
of friction/resistance even when under load” of the pivot that allows
the behaviour to occur.
Any ideas what might be happening ?
regards Paul
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