[python] Re: Rear Suspension
- From: "dirk@xxxxxxxxxx" <dirk@xxxxxxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Wed, 23 Feb 2011 14:08:06 +0100 (CET)
Hi,
yes, basically you are right. But don't forget, that a front fork also needs to
handle braking forces. In the case of mtb forks, you could brake on a normal
bike up to the point of rear wheel lift off, which should put quite some stress
on the fork. The same goes for hitting the curbside.
The bike in the picture seems to have some welding spots on either side of the
fork, about where the brakes sit. It looks to me that someone shortened the fork
for another wheel size....
On a python, most load is one the front wheel, which only gets more in case of
braking.
Also, you could have a damper between the frame and the seat. Reducing pressure
to 2bar would probably result in more rolling resistance.
greetings,
DirkS
Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx> hat am 23. Februar 2011 um
13:36 geschrieben:
>
> Hello,
>
> My triangular frame is very stiff and although I have 2" fat tires (@3-4bar)
> and some seat suspension, I do feel annoying vibrations on some roads.
> Probably it would help if I went to 2 bar for my tires and a thicker seat
> cushion.
> When I first saw the Python project with a front fork used in the back, I
> thought this couldn't be very stable/safe. The loads are at a 90 degrees angle
> of what it is designed for. But apparently it works and is strong enough. How
> does it ride with heavy loads? I thought it would be a bit like a women's bike
> compared to a men's bike: women's bikes are less stiff and can't really handle
> heavy loads when cornering.
> A problem could be kinda like this picture:
> http://jasondoesitall.com/bikewith2brains/2005704BrokenFork.jpg ; A front fork
> is not designed for heavy side loads. That wouldn't be the case for a Python
> though, it would bend in the other direction.
>
> Greetings,
> Patrick
>
> Date: Wed, 23 Feb 2011 12:05:37 +0100
> From: dirk@xxxxxxxxxx
> To: python@xxxxxxxxxxxxx
> Subject: [python] Re: Rear Suspension
>
>
>
>
>
>
>
>
> Romptekst bericht
>
>
>
> Hi,
>
>
>
>
>
> if you have a triangle between pivot, seat conection and brake mount/rear
>wheel, this should be stiff enough even with thin tubing. Also, you could
>design this triangle with just one tube going round and weld in a normal bike
>fork which also gives you brake mounts. Standard forks are quite optimised in
>terms of suspension.
>
>
>
> A fat rear wheel (which needs less pressure compared to thinner ones) also
>makes up for a fine suspension with low failure and maintance potential :-)
>
>
>
> greetings,
>
> DirkS
>
>
>
>
>
>
>
>
> Jaculus <jaculusbent@xxxxxxxxx> hat am 23. Februar 2011 um 11:45
>geschrieben:
>
>
>
> > no cracks, but the rear part of the jaculus is way to rigid. Riding
>
> > over anything but asphalt gives a headache because of the vibrations.
>
> > I would use smaller tubing for the next one, saves weight and improves
>
> > the ride.
>
> >
>
> > For the rear part of a (distant) future brother of the jaculus i was
>
> > thinking of two straight tubes from eighter side of the rear axle to
>
> > the sides of the pivot. These two should probably be connected just
>
> > before the rear wheel (also brake mount) for the top support of the
>
> > seat, and at the pivot.
>
> >
>
> > Jaculus
>
> >
>
> > 2011/2/23 Jürgen Mages <jmages@xxxxxx>:
>
> > > Hello Rod,
>
> > >
>
> > > it is not a bad idea to leave out the rear suspension. Considering
>the mount
>
> > > of effort, weight and the possibility of failure it seems not really
>worth
>
> > > to include a rear suspension.
>
> > >
>
> > > So, I am thinking of revising my building side:
>
> > >
>
> > > http://www.python-lowracer.de/construction.html
>
> > >
>
> > > The goal is, to simplify the building process and to save weight.
>
> > >
>
> > > As I never rode unsuspended Pythons, I am curious to hear some
>experiences
>
> > > from you and other riders. Any cracks of the rear frame yet?
>
> > >
>
> > > Cheers,
>
> > > Jürgen.
>
> > >
>
> > > On 22.02.2011 01:35, r.mccrady@xxxxxxxxxxx wrote:
>
> > >>
>
> > >> My wheel base is 114cm, with 26" (mountain bike standard) wheels. I
>
> > >> built it following the P3 instructions from Jurgen, but I didn't
>
> > >> include the rear suspension.
>
> > >>
>
> > >> -Rod McCrady Los Alamos, New Mexico, USA
>
> > >
>
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>
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> http://dirk.steuwer.de ;
http://dirk.steuwer.de
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