[python] Re: AW: Re: Questions about Python-Trike geometry (project similar to Howard Stevens foldable Python trike)

  • From: Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx>
  • To: <python@xxxxxxxxxxxxx>
  • Date: Mon, 1 Aug 2011 15:12:34 +0200

Ah, thanks for your explanation! Yes, having just rear brakes on a trike is not 
a good idea. A front brake will make all the difference.

I can't help you with the geometries, as I haven't tried (many) different 
setups.
My 'magic moment' was there when I temporarily attached two wheelchair wheels 
on my Python. Although the construction was weak and the track was too small, 
it did give me a sudden insight of how the Python was steered. On this trike 
the cycling was very easy. It appeared to me that steering wasn't the actual 
problem, but keeping balance was. That might sound like an open door, but when 
you steer on a Python your centre of gravity is actually shifted to the outside 
of the corner. That means that you have to lean more than on a conventional 
bike. I still have problems with that when I make sudden sharp corners.

Thanks,
Patrick


> Date: Sun, 31 Jul 2011 21:34:39 +0100
> To: python@xxxxxxxxxxxxx
> From: Rhisiart@xxxxxxxxxxxxxx
> Subject: [python] Re: AW: Re: Questions about Python-Trike geometry (project 
> similar to Howard Stevens foldable Python trike)
> 
> Hi Patrick,
> 
> Well since I wrote, I've put the trike back-end back on my Python, 
> just to have another think about it.
> 
> It rides really well, and I have literally instant control; had it 
> from the very first try out in fact, and went out on the road in 
> traffic that first day.
> 
> So what I'm doing now is putting a brake on the front wheel (I hadn't 
> done that before) and I'm fixing a method to pull on both back brakes 
> by a single hand lever. I may also try two brakes on the front wheel, 
> operated by both hands, if the back brakes are just hopeless. I'll 
> report results.
> 
> I must say too that being able to bank all of the trike, except the 
> rear-wheels frame, into bends, just like on the bike, is a real plus. 
> (Erik Wannee's training back-end photo shows you exactly the design 
> principle) It feels just like riding the bike, except that you have 
> those brawny handle-bars, fixed to the back end, to push down/pull up 
> on. I find that I do both at once when I feel myself going over. Just 
> like pushing frantically against the ground with your stretched 
> fingertips, but so powerful by comparison that you can stop all 
> fall-overs dead before they get going.
> 
>   And I've already noticed, even on my fairly short total time on the 
> banking trike that there is indeed a training effect for staying 
> balanced, so that you begin to be able to lift your hands slightly 
> off the bars for a few metres at a time. I suspect that with plenty 
> of use of the trike I should be able to ride the bike with 
> confidence, before long.  You can see from the videos that there's a 
> knack; that first-time riders suddenly get it. That's the magic 
> moment that I'm shooting for!
> 
> It does occur to me, though, that since we've all made our Pythons 
> ourselves, to no standard design, might it be that subtle, quite 
> small variations in bike geometry make all the difference between an 
> easy, sweet-riding bike where you get the knack easily and within 
> minutes, and a really tough dog? I seem to have made a tough dog. 
> Anyone got any ideas about that, based on experience with several 
> slightly differing geometries?
> 
> Hwyl,   Rh
> 
> >Are you saying that you abandoned a beautifull trike design because 
> >of rear wheel skiding when braking? I want to build a python trike 
> >myself, so I wonder why you would worry about it. I mean, if just 
> >the front wheel is enough for braking, then why bother about the 
> >rear? My two wheel Python doesn't even have a rear brake. Or is it a 
> >safety concern? Though, you could always fit multiple brakes on just 
> >the front.
> >Please let me know you thoughts,
> >Patrick
> >
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