Why two top tubes ?

Why two top tubes ?

http://tinyurl.com/37sbwo

Rik O'Shea wrote:
Why two top tubes ?

http://tinyurl.com/37sbwo

Two tubes are better than one:
http://tinyurl.com/2wghpd

On Oct 25, 6:18 am, Rik O'Shea wrote:
Why two top tubes ?

http://tinyurl.com/37sbwo

They must have given up on the "laterally stiff but vertically
compliant" nonsense.

wrote:
On Oct 25, 6:18 am, Rik O'Shea wrote:
Why two top tubes ?

http://tinyurl.com/37sbwo

They must have given up on the "laterally stiff but vertically
compliant" nonsense.

English roadsters 24.5" frames "for the taller gent" were built with
double top tubes. Tradition? IMHO they wanted to make stiffier frame...

C.

Coaster wrote:
wrote:
On Oct 25, 6:18 am, Rik O'Shea wrote:
Why two top tubes ?

http://tinyurl.com/37sbwo

They must have given up on the "laterally stiff but vertically
compliant" nonsense.

English roadsters 24.5" frames "for the taller gent" were built with
double top tubes. Tradition? IMHO they wanted to make stiffier frame...

C.
NIce bike with double TT:
http://www.uscoles.com/bikepix/073stpashleyl.jpg

C.

Rik O'Shea wrote:
Why two top tubes ?

http://tinyurl.com/37sbwo


two tubes are twice as stiff as a single tube
It's easy to build as you can use the same tubes and lugs (with a bit of
grinding on the seatlugears)


--
/Marten

info(apestaartje)m-gineering(punt)nl

Rik O'Shea schreef :
Why two top tubes ?

http://tinyurl.com/37sbwo

A strong man needs a strong bike!

http://picasaweb.google.com/koertmar...59047640721090

Koert

On Oct 25, 8:40 am, M-gineering wrote:
Rik O'Shea wrote:
Why two top tubes ?

http://tinyurl.com/37sbwo

two tubes are twice as stiff as a single tube
It's easy to build as you can use the same tubes and lugs (with a bit of
grinding on the seatlugears)

--
/Marten

info(apestaartje)m-gineering(punt)nl

Well, about 30% stiffer laterally, and way stiffer vertically
depending on the geometry. The question is, why double the top tube?
The down tube makes much more sense.

On Oct 25, 6:18 am, Rik O'Shea wrote:
Why two top tubes ?
http://tinyurl.com/37sbwo

wrote:
They must have given up on the "laterally stiff but vertically
compliant" nonsense.

Coaster wrote:
English roadsters 24.5" frames "for the taller gent" were built with
double top tubes. Tradition? IMHO they wanted to make stiffier frame...

Raleighs were built both with single and with double top tubes, the dual
top tube version not sold in USA. I tried to add some to a container of
bikes. They declined even though they were shipping dual tube models to
selected 3d world markets at the time. Raleigh's official statement,
"It's fashion".
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

On Thu, 25 Oct 2007 10:18:15 -0000, Rik O'Shea
wrote:


Why two top tubes ?

http://tinyurl.com/37sbwo

Dear Rik,

Partly for style, since double top tubes were popular around 1910:

http://www.fixedgeargallery.com/morley/04.jpg

http://www.fixedgeargallery.com/morley/06.jpg

Partly for strength for carrying loads slung across the top tube, a
popular habit in what the caption refers to as developing countries,
where riders may sling 200-300 pounds of cargo across the top tube and
trundle down a bumpy dirt road.

Cheers,

Carl Fogel