[python] Re: Thanks Chris! Any everyone else.
- From: Kelvin Arthur <kelvin.arthur@xxxxxxxxx>
- To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
- Date: Wed, 3 Apr 2013 22:51:56 +1300
Hi Ivan
Nice to have another Kiwi keen to do the python thing. I have built one here
down under, it started out as something of a mongrel and was progressively
modified over about a year to the final version for now.
My thoughts, having read a lot on the web, built, and riden. Don't worry about
suspension, if you're really concerned about a soft ride, build a textile seat
(some sort of sling arrangement), this softens the ride no end without
sacrificing too much in the power department. It is also easy to make and
adjust. I built a curved wooden seat for a Bachetta clone, rear wheel drive
recumbent recently, while a great seat, MUCH more work than the sling and it
makes the position of it much more critical.
As for pivots, I tried steering ball ends, complete disaster, I then went to a
cup and cone bb, less of a disaster, still not very good. I then got 2, 12mm
male tie rod ends and never looked back, easier to construct for, gives you
about 2 degrees of angle adjustment each way and plenty strong enough. The
final version of pythonui has an adjustable bb at the front for leg length, a
sling seat, and even with a 3 metre wheel base (yes, it's a monster!) and my 4
year old boy in the back, I never had the feeling that the pivot wasn't up to
the task. My python was transported by car a lot, being able to undo 2 bolts,
and have the bike split was a real bonus, and allowed me to get it into my
hatchback with ease, even the big version.
On the gears front, my early version had a derailer, while functional, I never
looked back after getting an in hub gear. It's only a shimano 3 speed, but
it's enough. Using an 8 speed hub gear with a coaster brake would have been a
real dream for me, but I built with no budget, scrounging what I could.
When you first build it, build it to be crashed, a LOT, it will save you the
heartache of having to repair your lovely work!
My few cents worth, and sorry for the novel.
Kelvin (yes, it turns out it is a very small world after all!)
Sent from my iPad
On 3/04/2013, at 21:46, Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx>
wrote:
> Hello,
>
> The option I use for an adjustable pivot point is a 'rod end joint'. You can
> see it here: http://cycle.free-creativity.com/images/python5.jpg The rod
> ends are protected by a rubber boot. The cheapest and best seller I have
> found is: http://mcgillmotorsports.co.uk/index.php?act=viewCat&catId=25 They
> have 3 types, but I prefer the 'High Performance'.
> At the moment I use M12 size, which is strong enough, but for my next project
> I am going for M14 as I am building a utility trike and needs to be very
> strong.
> Not sure how many degrees I can adjust the pivot, but it depends on your
> design (the distance between the two rod ends and the size of them). If you
> need detailed info about those rod ends, like thread length or max. angle;
> it's available (just ask).
> Though, you can't adjust the pivot 'on the go'. You need to detach the front
> and rear part and use shims to fit the rod ends on the pivot axle without
> play.
>
> Ivan, I don't think you need suspension. Of course, my big apple 26" tires
> are more comfortable than racing tires, but it is like you compare a ride on
> a mountainbike with fat tires to that of a racing bike, I think. My
> experience with recumbents in general is that a nice seat with a good cushion
> does also give you a more comfy ride.
>
> Greetings,
> Patrick
>
> Date: Wed, 3 Apr 2013 10:53:21 +0300
> Subject: [python] Re: Thanks Chris! Any everyone else.
> From: balamber@xxxxxxxxx
> To: python@xxxxxxxxxxxxx
>
> Hi Ivan,
>
> A working adjustable pivot is technically very difficult to do in my opinion.
> I tried to build a test bike with an adjustable pivot to test different bike
> geometries but it tended to buckle all the time. I would suggest that if you
> really need to change the bicycle geometry, instead of an adjustable pivot
> add front and/or back suspensions with a pretty large range of adjustment and
> use them to raise/lower the front and rear of the bike. This way you change
> the pivot angle as well.
> If anyone has a good idea/mechanism of an adjustable pivot with a +/- 15
> degrees of range or even more please share it. Infinitely adjustable/stepless
> adjustment preferred.
>
> That's my two cents.
>
> Tiha
>
>
> On Wed, Apr 3, 2013 at 10:09 AM, Ivan van Hoof <zl3tiv@xxxxxxxxx> wrote:
> That sounds like one nice seat! Bending ply or snake ply, I will have to make
> my seat out that stuff. Any thoughts on the main pivot? I like the simple
> bottom crank design but I want a design that is simple looking, sleek and
> adjustable angle by a few degrees to account for other riders weights and
> lengths. Good to see the group is active, very quick replies from you guys is
> great!
> I have shown, told a few work mate and friends the web site and they are keen
> to see me finish my python and ride it.( and a few think am crazy.)
> How smooth is the ride of these bike with 700c or 26 inch wheel on the road(
> no off road) would I need suspension? I intend to only use the bike for
> touring on the road. I'm thinking no suspension to save weight.
> Thanks guys for your help.
>
> Ivan van Hoof
> ZL3TIV
>
> Sent from my iPad============================================================
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