[python] Re: Evolution Bike

  • From: Jürgen Mages <jmages@xxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Wed, 27 Mar 2013 14:14:01 +0100

Thanks for understanding my bad english explanations ;-)
Regarding the optimum height of the BB above seat level there is a lot of discussion. It depends on the seat angle, sportive attitude and personal feeling. 20 cm with 35 degrees seat angle is my personal favorite. 

Here is a list with some python BB-Seat Diff. examples:

http://www.python-lowracer.de/projects.html

Jürgen.

On 27.03.2013 13:33, Tihamer Juhasz wrote:

Hi Jürgen,

I see. So optimum BB height is somewhere around seat height. As your say,
too low should be bad indeed for aerodynamics and pushing the rider up in
the seat.

Thanks.

Tiha



On Wed, Mar 27, 2013 at 1:32 PM, Jürgen Mages <jmages@xxxxxx> wrote:


Hi Tiha,

first argument pro high BB is better aerodynamics and second is better
force input.

I once rode the airbike which has a low BB. Especially when climbing, the
applied pedalling force is pushing my body up from the seat.

Jürgen.


On 27.03.2013 12:14, Tihamer Juhasz wrote:


Hi,

Please enlighten me. Why is a low BB compared to the seat a problem? Until
now I thought that a BB should go as low as possible, as long as the heels
don't hit the wheel or the ground when turning. A low BB has the
advantages
that pushing down from the higher seat is easier especially for climbing
compared to pushing upwards.
Furthermore when the BB is low, the angle between the steering axis and
imaginary line between the BB and the seat (the line along which you push
the pedal) is shallower and thus the pedal induced steering effect is
weaker.
These are two advantages of the low BB I know of. What are the
disadvantages?

I think that this steering angle will not work good in practice indeed.

Best, Tiha



On Wed, Mar 27, 2013 at 1:04 PM, Jürgen Mages <jmages@xxxxxx> wrote:

  Design is indeed nice and clean. Performance would be not so good. BB is

too low compared to the seat and even worse: the steering angle is too
small which causes the front wheel to flop in curves.

Jürgen.

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