[python] Re: question about pivot angle - 63-65 degrees
- From: Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx>
- To: <python@xxxxxxxxxxxxx>
- Date: Thu, 4 Oct 2012 11:10:35 +0200
Hey Matteo,
I am not really sure what you want. That's probably because your english is a
bit hard to understand, but also because you might not know what you exactely
want.
So here is something you might want to consider:
1) Yes, for a trike the pivot angle is still important, although less than for
a 2-wheeled Python. I think 63-65° is ok for a trike. It will handle
differently if you for example go to 50 or 80° but you will be able to cycle on
it. It is not as critical as for a Python.
2) What exactly do you mean with self centering effect? Usually when we talk
about a Python, the self centering effect means that the steering goes straight
(when sitting on the bike and doing nothing). But the video you show is a
leaning trike. Self centering for leaning is also possible. A very good website
on that is: http://jetrike.com
Although both leaning and steering interact, I think it is best to take them as
a separate design idea. So my question would be: do you want a leaning trike?
There are quite a few options for that. The Jetrike is one of those options.
That Bacurra (the picture you sent), might be another, but I can't really see
what the pivot point is. To me it seems like a combination of a
leaning/steering rear pivot, a bit like a Jouta trike
(http://www.joutaligfietsen.nl). The Sirio trike (in the video you sent) is yet
another option. By the way, the video shows two different leaning trikes: 1 has
the leaning and steering separate, 2 has a combination of steering and leaning
(leaning of the seat).
So, what kind of setup are you actually considering and discussing?
3) No, I don't think that the seat should be lower than the front wheel axle
and it doesn't have to do much with the self centering effect of the steering.
Even if you would place the seat at 10 metres for a normal Python, the self
centering effect of the steering would still work. Though, the Python would be
very very hard to handle (consider cycling a unicycle of 10m high).
But as Gerald said: for most trikes, a low center of gravity is preferred,
because otherwise the trike might flip in a corner. In my eyes: if you are
considering a leaning trike, things are quite a bit different. In theory, a
leaning trike can't flip, because you either lean enough in the corner and all
goes well, or you don't and you can't make the corner (much like a normal
bike). So in my opinion the centre of gravity (thus; the seat) can be higher
than for a normal trike.
If you want more help, I think it's best to make it more clear what you want.
Make a sketch of the pivot points and joints. Not just take a picture from the
internet. If you are going to build a trike you will need a good drawing of the
design anyway (at least, that's what I think). If you don't have the programs
for that, just use pen and paper and make a picture of it. I still do that for
most designs I make. Later on, you can always make a fancy PC drawing.
Hope this helps,
Patrick
> Date: Wed, 3 Oct 2012 22:30:29 +0200
> From: bepb@xxxxxx
> To: python@xxxxxxxxxxxxx
> Subject: [python] Re: question about pivot angle - 63-65 degrees
>
> Hi Matteo,
> I have to admit that the details of the steering and frame of your trike
> are no clear to me, not from the picture or the description.
> But I maybe I can still help a bit.
> 1) 63° is a fine pivot angle for a two wheel python. For the python
> trike I made good experience with a pivot angle of about 50°.
> 2) Again the point about the "couple of connection between the 2 frames"
> is not clear to me.
> 3) In general, its good for a trike to have a as low a center of gravity
> as practical possible.
>
> BR
> Gerald
>
>
>
> On 27.9.12 10:48 , mtzolo@xxxxxxxxx wrote:
> > Hi
> >
> > I'm here asking a question about the pivot angle.
> > I'm bulting a trike like baccura
> > http://kb7mxu2.home.mindspring.com/images/baccura.jpg
> > in that case, with 2 point linking front frame + seat (single block)
> > TO rear frame,
> >
> > 1. about 63-65° of the pivot near front wheel are still significant to
> > self centering effect?
> > 2. well.. here it still exist a self centering effect (I mean, with a
> > couple of connection between the 2 frames?)
> > 3. the seat should be lower than the front wheel axle? Or the point to
> > self centering effect still remain the pivot angle?
> >
> >
> > I know.. that questions are beyond pyhon design, but they concern the
> > world of recumbent anyway!
> >
> > many thanks
> >
> > Matteo
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