[python] Re: Handlebars mounted
- From: "25hz" <25hz@xxxxxxxxxx>
- To: <python@xxxxxxxxxxxxx>
- Date: Fri, 8 Apr 2005 21:52:59 -0400
Aye, I built myself a 5 speed unicycle for myself when I was 12 out of a
scrapped 20" bike. Even though it was "scary tall" initially, I was sort of
surprised how easy it was to learn to ride it.
My friend and I were sitting looking at his python (with the same
considerations for mine) and decided on a plan of attack.
1) make seat mount extensions to raise the seat and thereby the CoG. We'll
start with 2", then 4", etc, and we'll see at what point, or if, he notices
that the python gets a little easier to control. Hopefully the fact that
he's spending more time on it won't cloud the advantage of changes in CoG
height, if any. Another friend can almost ride the python, so we can also
see if the increased seat height aids his learning curve as well. I will
also try it and see if it helps. Once confidence is gained, we'll
experiment with lowering the pythons back to their original seat heights.
2) remount the handle bars because we definitely need someplace to mount
gear changers and brakes. They will be mounted much more robustly so as to
actually provide a solid item vs the semi-wobbly ones that we initially
installed. We will also make them replaceable as they definitely take a bit
of a beating during the learning curve.
3) depending on the success of item "1)", we will mod the pivot angle, as
mentioned in the previous post, by notching the frame, closing the gap, and
welding it back up. We measured the pivot at between 69 and 70 degrees. As
the frame on the MD python flexes a little for passive suspension, it
probably ends up around the 68 degree mark. The frame on mine is a little
stiffer, so it likely stays closer to 70 degrees. By notching the main
frame section under the seat, one cut should take 4 to 5 degrees out of the
pivot angle and leave us with something in the 64 to 65 degree range. After
that, we'll try riding them again and see if the handling has
changed/improved. We'll then try the 2" and 4" seat height extensions as
well.
The end goal is for all three of us to ride the pythons back and forth to
work. We want to take rigid 1/2" foam, glue up rigid tailbox/saddlebags,
and lay up a layer of fiberglass on the inside and outside of each for
stiffness. These will act as a tailfairing, rear fender and storage for the
items we need to transport to and from work. The route is about 25 km one
way and we're looking forward to ripping down the road in a three bike pace
line.
> > With a higher CoG, the bike needs to lean a
> > larger distance left or right before you wipe out, and that gives the
> > rider
> > more time to react with smaller correction inputs. With a low bike, it
> > seems that you have very little time to react to balance issues and
> > your
> > corrections need to be more precise than with a higher bike.
>
>
> Riding different unicycles from 20" to 36" (probably the largest air
> filled tyre being produced) I recognise this very well. On the big
> wheel you have more time to correct a sudden imbalance but it is also
> heavy to do so, when leaning too much away from centre line you might
> as well jump off. This is essentially the broom stick effect where it
> is much easier to balance a broom stick on your finger tip than for
> instance a pencil. If you're riding a giraffe (a very high unicycle)
> this effect will have even greater influence. One can speculate that
> the riders of Penny Farthings in the late 1900-century had much use of
> this effect when riding along bumpy bridleways on their 50–60 inch
> wheels.
>
> olaf
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