[python] Re: Leaning trike

  • From: Henry Thomas <whpthomas@xxxxxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Mon, 2 Jul 2012 09:10:31 +1000

Hi Patrick,
My jetrike would corner very aggressively, but what I didn't realise was that you really load up the front wheel, so if it slips, you crash - plain and simple. I never did it on tarmac, but once on gravel - although I did have a few near misses. Once when I was avoiding another rider in a group ride, I felt the front go, but it hopped, and gripped again and luckily recovered - I was doing about 28km/h at the time. Sometimes its a good idea to just slow down when taking corners on a trike :)
Also regarding tilt lock - I was contacted by a guy who build a Jetrike style hybrid electric, who had put disk breaks on the rear wheels. He had discovered that putting a single break leaver that drove both rear break lines caused the tilt to lock by simply holding the brake on both rear wheels, this was because the wheels need to turn back and forth in order to tilt. This is a very simple approach and very complementary to riding - you generally want tilt lock when you stop, which involves applying the breaks.
Also the width doesn't change that much, and you are generally heading straight, when you pass through bollards. 

-h

Dr. Henry Thomas

On 02/07/2012, at 7:30 AM, Patrick van Gompel wrote:


Hey Vi,
My idea of my Pythontrike being too stable is caused by the inability to take sharp corners at high speed. On my regular cycling road to work, there is a 90 degree turn and I often tried to take it at higher and higher speeds. But at -let's say- 25km/h I am unable to smoothly lean/steer enough to take the corner. It just doesn't want to lean enough to be able to take the corner at that speed. Only if I start to lean very early in the corner (more than actually needed) and then when being in the middle of the corner add some body weight, I am able to take higher speed turns. Or, another option is to throw myself into the corner forcefully (using body weight). Because of the arms of the jetrike, the rear becomes wider when turning. Estimating the width of your trike, whether you can fit inbetween two poles, becomes harder. I have a general feeling of the width of my trike and trailer, but when I take a corner the width changes and sometimes I hit the edge of a bump/pole or whatever, when I take a corner. And since the width of my trike is rather close to the usual door width of buildings, I always need to put my bike in a straight position when going through it. Just some practical things, but sometimes it's annoying. And yes, when my front wheel is going to slip, the trike becomes rather unstable.
Oh sorry, no, my video was from the rear (delta trike like I have now). There is a little Lego man on it facing the proper position, but that might have been unclear, haha. No I haven't considered a tadpole trike since I definately need two wheels in the rear. The reason for that is that I need to pull a heavy trailer and the best option for a hook is inbetween two rear wheels. That's a nice bike in your video, but I would prefer a separated leaning and steering input for my usage. So that I can change how much I lean when taking a corner. 

Patrick


Date: Fri, 29 Jun 2012 20:42:43 -0700
From: vi_vuong@xxxxxxxxx
Subject: [python] Re: Leaning trike
To: python@xxxxxxxxxxxxx

Hi Patrick,
Please clarify if you mean "pythonjetrike still seems to be too stable ... when cornering" or unstable with track width changing, and also the riding surface (tarmac, dirty, snow...) I am guessing that you meant unstable on a loose surface.
On your video at first glance, the lego prototype looks like a tadpole trike. Have you consider such design? Just FYI, on a tadpole w/ center steer the track is fixed and the upper body leans with the rear frame into the corner to turn, so the motion is more natural and stable compared to non-tilting delta / tadpole trike. Trouble with this design is that FWD is more complicated than RWD (axle or outrigger like this one http://www.youtube.com/watch?v=WTM85zmWPnA) 

Cheers,

Vi
On Jun 28, 2012, at 12:00 PM, Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx > wrote: 

Thanks for the input guys.
Yes Henry, I have been looking at your design before (nice idea indeed). The reason I want a different setup is that I prefer more control over the suspension (especially when a trailer is attached). When using a air spring I can easily adjust tension and rebound, or could even lock it when the trailer is too bouncy on the rear. I hope this new design will solve my problems with high speed cornering too. My pythonjetrike still seems to be too stable and I think I prefer a steady trackwidth when cornering. I am also thinking about front suspension, because -as you say- it gives more benefit to the whole. Though, that will be a different story. 

Greetings,
Patrick


From: whpthomas@xxxxxxxxx
To: python@xxxxxxxxxxxxx
Subject: [python] Re: Leaning trike
Date: Fri, 29 Jun 2012 04:22:39 +1000
Here are some photos of how I resolved the addition of suspension to my tilting trike using elastomers. In reality, the front wheel carried a greater proportion of the riders weight, so the benefits of adding suspension to the rear was limited - though it did make some difference. 

<BILD0453.jpg>

<BILD0455.jpg>

http://jetrike.com/jetrike-mods.html

Kind regards,

-h

On 28/06/2012, at 9:57 PM, Patrick van Gompel wrote:

Hello,
I am planning to build a new leaning Python trike and made a simple setup out of Lego. 
See: http://www.youtube.com/watch?v=uZ7Gv4rE-Vk
Does anyone have experience with this kind of leaning/suspension? Any ideas about pros and cons? 

Thanks,
Patrick

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