[python] Re: pivot quality

..and the flevobearings very much resembles wheelbearings. I'm sure you can 
get both housing, axle and bearings at http://www.ligfietsshop.nl/. More 
expensive than wheelbearings, though - but a carhub and wheelaxle is'nt 
normally suited to be used on a  bike :-)
Cheers,
Torben

-----Original Message-----

From: Thomas P Jahn <tpj@xxxxxx>

To: python@xxxxxxxxxxxxx

Date: Wed, 11 Apr 2007 09:54:04 +0200

Subject: [python] Re: pivot quality





Hey August,



you name it. I was thinking of such a pivot using "aircraft
rods". I just didn't know, how they are called. :-)

The idea was to use two of them in order to have an adjustable
pivot angle without changing other aspects of the geometry. The lower
bearing could be fixed and the upper one should be movable forth and
back.



www.aurorabearing.com/products/aerospace-military/aerospace-series/rod-ends/male/default.html



I am a little in doubt though that 2 "aircraft rods"
will give sufficient strength/support. Therefore, I was thinking of
using a ball bearing from a cars front wheel suspension as the lower
bearing. Those bearings are very stable and carry 300 kg when the car
is just standing still. The dynamic forces must be much higher.



http://www.yatego.com/atv-schiffke/p,44c9c353c6afa,434630b1776d88_0,vw-traggelenk-vw



I think that should work.



cheers

Thomas











I was looking over
various pivot designs on all the Phyton bikes and was wondering about
the aircraft type rods they look pretty simple to consruct but.is
there any info on how they work and hold up I relize aircraft spec
parts are extremly strong but they were never inteaded to be use
as pivot bearings under so much weight is that a
proplem?


----- Original Message -----

From: Torben
Scheel [mailto:torben@xxxxxxxxxx]

To: python@xxxxxxxxxxxxx [mailto:python@xxxxxxxxxxxxx]

Sent: Tuesday, April 10, 2007 11:42 PM

Subject: [python] Re: pivot quality



Hi Dirk!



It is ball bearings, right? Roller bearings is a lot
better for the purpose, but the stress on the pivot _is_ extreme. I
have not ridden my Python enought to say if the Flevopivot is better,
but I'd expect it, even if it isn't designed for the tilting
force.

As for the rust - you'll notice that a lot of the danish
bikes is coated with a layer of a chemical (usually pigmentated)
called "paint". It helps in some extent - the powder version
is the toughest, but it kind'a limits your tinkering, when it's
applied :-)



Cheers,

Torben


-----Original Message-----

From: dirk.bonne@xxxxxxx

To: python@xxxxxxxxxxxxx

Date: Tue, 10 Apr 2007 21:54:53 +0200

Subject: [python] Re: pivot quality

Hi Jürgen,



To make a good photo of such a little thing is easier asked then
done.

It rises far above my abilities with the camera to make a photo of
the

small dents in the bearing cap. I attached my best result ---still

better then some of the UFO photos but not a lot. With a little bit
of

good will on your side, you can see the dents at regular distances
on

the inner cap. I can easily feel the dents by going over the cap
wall

with my finger nail. The dents are nearly all around with some
places

are worse (I suspect the front or back). All the caps have dents.



Now for the reason, I do not want to give the full fault to the

bearings. I have mistreated them by heating them up (I did not braze
on

the shell directly, but I remember welding my handlebar tube on
the

frame while having the bearings in and that may have been near
enough).



Anyway I do not think this pivot solution is so neat: These bearings
are

not sealed, and even though I filled the pivot up with grease, there
was

still a lot of sand in it (I attached a photo of the pivot shell
where

you see the flimsy sealing solution I choose: just a spacer above
and

below). You can also see the rust: Denmark has not only a lot of sand
it

is also very salty...



liebe Grüße,

Dirk



Jürgen Mages wrote:

> Hej Dirk,

>

> did you use these bearings:

>

> http://dirkb.dnsalias.net/image/python/skf_7201B.half.jpg 
[http://dirkb.dnsalias.net/image/python/skf_7201B.half.jpg]

>

> As far as I remember, Eduardo from Brazil used the same

> type of angular contact ball bearings (Schrägkugellager).

>

> If so, these pivot types are left for the choice:

>

>  - tapered roller bearings

>  - rod end bearings

>  - cartridge bottom bracket

>

> Could you please send us a photo of the destroyed bearings?

>

> Groetjes,

> Jürgen.

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