[python] Re: Moving the Pivot point behind the seat?
- From: "25hz" <25hz@xxxxxxxxxx>
- To: <python@xxxxxxxxxxxxx>
- Date: Mon, 17 Apr 2006 22:16:58 -0400
NP Jurgen. I looked at the project page and it amazes me how many
variations there are, subtle or otherwise, on your original design. I still
like to hang off to the rear and slightly to the side and watch Marcel ride.
The python is such a unique looking bike, especially when being ridden. I
need to take a few more measurements on the pythons and send you the stats
so everything is updated like weight bias, BB to axle and EOS, and turning
circle.
Marcel is funny with regards to the latest (and hopefully last) changes to
his python. He's very picky about what he likes and doesn't like when
dealing with handling, yet he keeps making changes. Part of his beef before
making the latest changes was he felt the python wasn't handling right after
his 50kph+ wipe-out into a guard rail. We thought we'd got all the kinks
out of it, but he still wasn't happy. I think too many things were bent a
little bit, which ended up with big handling issues when all the little bent
things were added up. On the final mods, we made sure everything was
absolutely lined up before welding it up. The slightly shorter wheelbase
and the steeper pivot angle made it a little "faster" reacting than he was
used to, but he's pretty happy with it now.
The low ground clearance would have been an issue with the frame the way it
used to be, because there was a little bit of bounce in it. It made for a
nice ride, but when 100kg guys like me rode it, or Marcel hit a bump hard,
it would bottom out. Never caused a big problem though. With the new frame
configuration, he immediately complained about how "rough" the ride was.
Mine rode like that from the beginning so I just kept calling him a whiner.
LOL Anyway, he's used to the stiffness now, and I think he likes the firm
feel when he's pedalling hard. Marcel is a pretty light guy, about 70kg,
but he's very strong for his size, so with the stiff frame and his light
weight, I don't think he'll ever have a problem with bottoming out on it
now.
As for his brakes, every time we did a mod, I tried to add a second brake,
but he always stopped me :) Not sure why, but he's a bit of a "weight
weenie" and he's never had any more than one brake on it for road use, and
doesn't believe he needs the extra weight or stopping power. When
decellerating, he likes to use his left hand on the brake and right hand for
downshifting. For me, I use my right hand on the rear brake until I am
pedalling too slowly for the gear I'm in, then switch to braking with my
left hand while I gear down with my right. Sort of complicated and it
doesn't make for smooth emergency braking yet, but I;m working on it :)
When we turned Marcel's into the ice racer, it was the only time he had 2
brakes on it. It's hard to see in the picture, but it has a rim brake just
above and in front of the pivot, and the second one just behind and below
the BB.
http://www.fleettrikes.com/md%20ice%20python%20side%202.jpg
As soon as the ice racing was done, we did the frame conversion and he cut
both the brake mounts off - so now he had zero. He decided to go with a 16"
rear wheel but didn't want me to shorten the rear forks, so we decided to go
with a disc brake on the front instead of more rim brakes.
Marcel did the holes primarily to try to lose some weight because the frame
was way overbuilt for his weight. I don't think it even saved a kilo of
weight, but I think it looks kind of swanky. :) That's the primary reason
why I did the same thing to mine, plus maybe losing a little frame weight.
As for the small wheels, I'm not much of a conformist and symmetry will
never be one of my strong suits. For me, I wanted the python to be as easy
to put in my van as possible, and that meant lighter weight and shorter
length. An easy way to do both was to simply drop a smaller rear wheel on
it so that I could lighten and shorten it, but still keep the same wheelbase
I was used to/liked riding. Marcel was doing a major frame change, so he
said to heck with it and went for the small wheel too. We both have very
high PSI tires (100 to 110psi) on the rear wheels so as far as we can tell,
they roll every bit as good as the high pressure 26" wheels we used before.
The only reason we stopped at 16" is because it's nearly impossible to find
good wheels and high quality tires in the 12" size :)
As a side note, I'm working on getting a Baron clone ready for racing in a
few weeks, and once it's rideable, I'm going to get the PC2 back on the road
by converting it back to a "normal" python. I'll send you some final
pictures with all the stats once that is completed.
Happy trails :)
> Thanks Tim,
>
> I updated the specs on the project side and changed the pictures.
> It is always a pleasure to read your reports :-)
>
> Now that Marcel´s python changed its pivot angle from 70 to
> 63, are there any changes in riding and turning behaviour?
>
> The low ground clearance does not seem to be an issue for Marcel.
> Also the lack of a rear brake ;-)
>
> The holes in the frame are really stylish.
> Also your small rearwheels are very unique! When I first saw them,
> they did not match my sense of symmetry, but now I am beginning
> to like them.
>
> Cheers,
> Jürgen.
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