Mating head tube to novel fork

EXECUTIVE SUMMARY
I want to use a fork constructed of small diameter tubes in the form
of an elongated diamond running all the way up to the stem. The
question is how to mate this fork to the very tall head tube,
preferably without using a full length steerer tube, which would be
superfluous as the four small diameter tubes of the fork diamond
provides all the stiffness and strength required.

THE STORY SO FAR

1. Chalo related in another context that triple clamp forks for
motorcycles have done away with the steerer tube, leaving only stubs.

2. Clive mentioned the Maverick DUC32 fork as an example, but
unfortunately the photographs at the Maverick site are of such low
resolution that I learned nothing useful.

3. "rcousine" (Ryan Cousineau?) referred me to
http://www.tonyfoale.com/gallery/Fro...elever_jpg.htm
which is interesting (and more ingenuity on the same site), though I
want something much, much simpler; and I don't need any suspension.

IDEAS?


Andre Jute
Looking for Ms Eureka...

On 09/08/2010 22:39, Andre Jute wrote:
EXECUTIVE SUMMARY
I want to use a fork constructed of small diameter tubes in the form
of an elongated diamond running all the way up to the stem. The
question is how to mate this fork to the very tall head tube,
preferably without using a full length steerer tube, which would be
superfluous as the four small diameter tubes of the fork diamond
provides all the stiffness and strength required.

THE STORY SO FAR

1. Chalo related in another context that triple clamp forks for
motorcycles have done away with the steerer tube, leaving only stubs.

2. Clive mentioned the Maverick DUC32 fork as an example, but
unfortunately the photographs at the Maverick site are of such low
resolution that I learned nothing useful.

Try looking a bit further.

http://www.maverickbike.com/cms_images/file_7.pdf

You'll still want something going through the frame.

On 9 Aug, 22:39, Andre Jute wrote:
EXECUTIVE SUMMARY
I want to use a fork constructed of small diameter tubes in the form
of an elongated diamond running all the way up to the stem. The
question is how to mate this fork to the very tall head tube,
preferably without using a full length steerer tube, which would be
superfluous as the four small diameter tubes of the fork diamond
provides all the stiffness and strength required.

THE STORY SO FAR

1. Chalo related in another context that triple clamp forks for
motorcycles have done away with the steerer tube, leaving only stubs.

2. Clive mentioned the Maverick DUC32 fork as an example, but
unfortunately the photographs at the Maverick site are of such low
resolution that I learned nothing useful.

3. "rcousine" (Ryan Cousineau?) referred me to
*http://www.tonyfoale.com/gallery/Fro...elever_jpg.htm
*which is interesting (and more ingenuity on the same site), though I
want something much, much simpler; and I don't need any suspension.

IDEAS?

Tequila slammers!


Andre Jute
Looking for Ms Eureka...

Andre Jute wrote:

I want to use a fork constructed of small diameter tubes in the form
of an elongated diamond running all the way up to the stem. The
question is how to mate this fork to the very tall head tube,
preferably without using a full length steerer tube, which would be
superfluous as the four small diameter tubes of the fork diamond
provides all the stiffness and strength required.

Pedersen bicycles use a rod end bearing and yoke (or something very
similar) on the bottom. There is no reason I can tell that one could
not be used similarly on the top, as long as it was rated to tolerate
the anticipated peak thrust loads.
http://www.pedersen-bike.dk/images/ped15a.jpg

A right angle spherical bearing might be simpler to implement and
possibly more satisfactory in your application:
http://www.mcmaster.com/#60745k661/

See also the unorthodox steering bearings on the Strida folder:
http://www.strida.nl/english/admin/f...a_blog_UK2.jpg

Chalo related in another context that triple clamp forks for
motorcycles have done away with the steerer tube, leaving only stubs.

The ones I remember having seen were not recent, but probably early
'80s vintage at the latest. I tried and failed to find a picture for
you.

Ryan Cousineau referred me to
*http://www.tonyfoale.com/gallery/Fro...elever_jpg.htm

Here is a bicycle-centric version:
http://files.myopera.com/chernobel/a...prst-4-lrg.jpg

Chalo

On Aug 9, 10:55*pm, Clive George wrote:
On 09/08/2010 22:39, Andre Jute wrote:





EXECUTIVE SUMMARY
I want to use a fork constructed of small diameter tubes in the form
of an elongated diamond running all the way up to the stem. The
question is how to mate this fork to the very tall head tube,
preferably without using a full length steerer tube, which would be
superfluous as the four small diameter tubes of the fork diamond
provides all the stiffness and strength required.

THE STORY SO FAR

1. Chalo related in another context that triple clamp forks for
motorcycles have done away with the steerer tube, leaving only stubs.

2. Clive mentioned the Maverick DUC32 fork as an example, but
unfortunately the photographs at the Maverick site are of such low
resolution that I learned nothing useful.

Try looking a bit further.

http://www.maverickbike.com/cms_images/file_7.pdf

You'll still want something going through the frame.

Thanks, Clive. I can now see the DUC32 works by removing the top
crossbrace, slipping the head tube over the steerer substitute, and
bolting the top brace back. This is exactly what I don't want to do
when my fork is constructed of a bunch of small diameter tubes --
that's a ballsup waiting to happen. But all the same I'm glad to make
the acquaintance of the DUC 32, which is novel and appears robust. --
Andre Jute

On Aug 10, 7:06*am, Chalo wrote:
Andre Jute wrote:

I want to use a fork constructed of small diameter tubes in the form
of an elongated diamond running all the way up to the stem. The
question is how to mate this fork to the very tall head tube,
preferably without using a full length steerer tube, which would be
superfluous as the four small diameter tubes of the fork diamond
provides all the stiffness and strength required.

Pedersen bicycles use a rod end bearing and yoke (or something very
similar) on the bottom. *There is no reason I can tell that one could
not be used similarly on the top, as long as it was rated to tolerate
the anticipated peak thrust loads.http://www.pedersen-bike.dk/images/ped15a.jpg

I like your idea below about the tie rods better. The yoke looks
clumsy, too self-consciously techy-freak-geek.

A right angle spherical bearing might be simpler to implement and
possibly more satisfactory in your application:http://www.mcmaster.com/#60745k661/

This is a superior idea, Chalo. It can be implemented with a fully
built fork soldered at all points (as I explained to Clive, I don't
want to have to disassemble any part of the fork to attach it to the
bike), with two horizontal plates soldered inside the fork to hold the
rod ends. Simple and clean.

You'll be amused to know that I woke up this morning thinking, "Rose
joints are not only for hot rods."

See also the unorthodox steering bearings on the Strida folder:http://www..strida.nl/english/admin/...a_blog_UK2.jpg

The Strida appears not so much simple as crude.

Ryan Cousineau referred me to
*http://www.tonyfoale.com/gallery/Fro...elever_jpg.htm

Here is a bicycle-centric version:http://files.myopera.com/chernobel/a...prst-4-lrg.jpg

Too complicated and ugly for me. (I did on several occasions though
spend an inordinately amount of time trying to find a large size NOS
Look Fournales parallelogram fork...) Anyway, I don't need suspension.
The Big Apples and the sprung Brooks saddle will do me. I am trying
not to lose from sight that I started on this odyssey to achieve the
simplest, most maintenance-free bike possible within my functional
requirements.

Andre Jute
Down with the spoilsport Telemachus!