[python] Re: Evolution Bike

  • From: Pascal Buenzli <pascal.buenzli@xxxxxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Thu, 17 Feb 2011 21:32:57 +0800 (WST)

Hi All,
The pivot looks more like a flevo bike and one may expect quite a bit of wheel flop with such wide pivot angles (almost horizontal), as described in the python wiki page <http://en.openbike.org/wiki/Wheel_Flop> ?
I think it would be safe to assume indeed that the planetary gears of the NuVinci-like bottom bracket (BB) gear hub serve to crank up the speeds (surely they have checked that you can go > 10km/h...). Such BB hubs seem to be yet rare on the market, I haven't seen this one, it might be their own design. However, I have seen two-speed ones mentioned on sheldonbrown, produced by a swiss company called Schlumpf: <http://www.schlumpf.ch/hp/schlumpf/antriebe_engl.htm> <http://www.sheldonbrown.com/harris/schlumpf.html>
In fact, the design of the 'evolution bike' seems virtually identical to the idea of Kretschmer (2000), with perhaps a more streamlined touch. If you own a copy of "Bicycling Science", by Wilson and Papadopoulos (2004), look at Figure 9.18. Alternatively, Kretschner's full-text article is freely available there (see p.11): <http://www.ihpva.org/HParchive/PDF/hp49-1999.pdf> 
A (discrete) 11 gear BB hub is also described in that article.

I actually like that idea. No chain = no pain.

All the best,
Pascal

On Thu, 17 Feb 2011, George Durbridge wrote:


Assuming that the Evolution used an unmodified Nu Vinci CVT and a 26"
driven wheel, I worked out that it would have gearing from 13" to 47",
which is very low, leading to the scenario Uipko described. The Nu Vinci
site suggests doubling these numbers by driving their gearbox through a
40-tooth chainwheel and a 20-tooth sprocket, but that is impractical
with the Evolution design.

(I think that 13" gearing is equal to about 1 metre development, and 47"
to about 3.5 metres. The gear inch measurement is the diameter of an
imaginary wheel, and I think the development is the circumference of the
same wheel.)

Following up Marek's link, I now see the gearbox contains a planetary
stage, as well as the CVT stage, more or less like putting a Schlumpf
transmission into the same housing as a Nu Vinci. It won't be light,
cheap or stepless, but it should lift the gearing to a useful range. The
Nu Vinci exists, but Marek is right to ask whether any such combined
transmission is on the market.

On Thu, 2011-02-17 at 12:20 +0100, Ronald Hongsermeier wrote:

Hi George,

Curious as to your reasoning?

regards,
Ron


On 17.02.2011 09:38, George Durbridge wrote:

It looks like the Nu Vinci continuously variable transmission.  It
exists, but won't work very well in that application.

On Thu, 2011-02-17 at 09:19 +0100, bnmm@xxxxxxx wrote:

Hi,



Evolution bike

better quality photos at:
www.behance.net/RoelVerhagen/frame/633553

I wonder if the front hub transmission is only a design idea, so far.


Cheers,
Marek




============================================================

This is the Python Mailinglist

//www.freelists.org/list/python

Listmaster: J???rgen Mages jmages@xxxxxx

To unsubscribe send an empty mail to
python-request@xxxxxxxxxxxxx
with 'unsubscribe' in the subject field.

============================================================



-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1204 / Virus Database: 1435/3448 - Release Date: 02/16/11





-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1204 / Virus Database: 1435/3448 - Release Date: 02/16/11

============================================================

This is the Python Mailinglist

//www.freelists.org/list/python

Listmaster: Jrgen Mages jmages@xxxxxx

To unsubscribe send an empty mail to
python-request@xxxxxxxxxxxxx
with 'unsubscribe' in the subject field.

============================================================




============================================================

This is the Python Mailinglist

//www.freelists.org/list/python

Listmaster: J??gen Mages jmages@xxxxxx

To unsubscribe send an empty mail to
python-request@xxxxxxxxxxxxx
with 'unsubscribe' in the subject field.

============================================================



============================================================

This is the Python Mailinglist

//www.freelists.org/list/python

Listmaster: Jürgen Mages jmages@xxxxxx
To unsubscribe send an empty mail to python-request@xxxxxxxxxxxxx 
with 'unsubscribe' in the subject field.

============================================================

Other related posts:

  1. Home
  2. python
  3. Archive
  4. 02-2011