Why two top tubes ?
Cycling Equipment · Public discussion
Why two top tubes ?
Thread navigation
Jump through the discussion
Go to the original post, the replies on this page, or the latest preserved contribution.
Thread details
What we know about this thread
- Original section
- Cycling Equipment
- Published
- 25 October 2007
- Last activity
- 27 October 2007
- Original author
- Rik O'Shea
- Posts
- 33
- Discussion status
- Public discussion
- Total views
- 458
- Views / 30 days
- 0
The navigation and discussion metadata provide context. Posts remain in their original chronological order.
-
-
Rik O'Shea said:
Why two top tubes ?
Two tubes are better than one:
http://tinyurl.com/2wghpd -
Rik O'Shea said:
Why two top tubes ?
They must have given up on the "laterally stiff but vertically
compliant" nonsense. -
Quoted message said:
Rik O'Shea said:
Why two top tubes ?
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 said:
Quoted message said:
Rik O'Shea said:
Why two top tubes ?
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.jpgC.
-
Rik O'Shea said:
Why two top tubes ?
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)--
/Marteninfo(apestaartje)m-gineering(punt)nl
-
Rik O'Shea schreef :
Quoted message said:
Why two top tubes ?
A strong man needs a strong bike!
http://picasaweb.google.com/koertmarinissen/Fiets/photo#5016259047640721090
Koert
-
Rik O'Shea said:
Why two top tubes ?
Why not?
(Oh, and those freakishly long, thin head tubes, too.)
-
M-gineering said:
Rik O'Shea said:
Why two top tubes ?
Quoted message said:
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)--
/Marteninfo(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. -
Quoted message said:
Quoted message said:
Rik O'Shea said:
Why two top tubes ?
http://tinyurl.com/37sbwoQuoted message said:
Quoted message said:
They must have given up on the "laterally stiff but vertically
compliant" nonsense.Coaster said:
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 <[email hidden]>
Quoted message said:
Why two top tubes ?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
-
Rik O'Shea said:
Why two top tubes ?
Quoted message said:
On this particular bike, i think it's a mistake, as the frame seems to
be a 23" (58.5cm) c-t frame. The top tube is the least-stressed tube
on the bicycle, because it's under compression. The downtube is the
most-stressed tube.However, when the seat tube and head tube get very long, I think there
are a lot of twisting stresses on these tubes (because, for example,
all my indexed / spalled / fretted / whatever headsets are on bikes
24" or larger ... whereas none of my smaller bikes ever had this
problem.)- Don Gillies
San Diego, CA -
In article
<[email hidden]>,Quoted message said:
M-gineering said:
Rik O'Shea said:
Why two top tubes ?
Quoted message said:
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)--
/Marteninfo(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.And putting gussets on the bottom bracket shell even more sense
but it is not done. Any frame makers here to comment?--
Michael Press -
Quoted message said:
Quoted message said:
Quoted message said:
Rik O'Shea wrote:
> Why two top tubes ?
> http://tinyurl.com/37sbwoQuoted message said:
Quoted message said:
M-gineering said:
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)
info(apestaartje)m-gineering(punt)nlQuoted message said:
Quoted message said:
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.Michael Press said:
And putting gussets on the bottom bracket shell even more sense
but it is not done. Any frame makers here to comment?The examples I can think of (3Rensho, Zunow) with cast gussets didn't
sell well. I believe you may yet have a frame made with the 3Rensho
flanged-sides BB casting from Jackson-Hetchins.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971 -
Michael Press said:
In article
<[email hidden]>,Quoted message said:
M-gineering said:
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)--
/Marteninfo(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.And putting gussets on the bottom bracket shell even more sense
but it is not done. Any frame makers here to comment?Anything makes more sense than a double toptube, until you add the
constraint that you have to use existing parts only. And if it sells:
problem solved--
/Marteninfo(apestaartje)m-gineering(punt)nl
-
On Thu, 25 Oct 2007 12:10:09 -0700, Michael Press <[email hidden]>
Quoted message said:
And putting gussets on the bottom bracket shell even more sense
but it is not done. Any frame makers here to comment?There's a couple guys who know a _lot_ about metallurgy who I'm sure
can comment!:-)
-
On Thu, 25 Oct 2007 10:18:15 -0000, Rik O'Shea <[email hidden]>
Quoted message said:
Why two top tubes ?
Retro? Lots of olde bikes had dual top tubes.--
Posted via a free Usenet account from http://www.teranews.com -
In article <[email hidden]>,
(Donald Gillies) said:
Rik O'Shea said:
Why two top tubes ?
Quoted message said:
On this particular bike, i think it's a mistake, as the frame seems to
be a 23" (58.5cm) c-t frame. The top tube is the least-stressed tube
on the bicycle, because it's under compression. The downtube is the
most-stressed tube.It seems to me that tubes do not fail, typically.
Joints fail.
* down tube -- head tube.
* down tube -- braze on.
* any tube -- bottom bracket.
* chain stay -- drop out
* chain stay -- brake bridge
* seat stay -- seat tube--
Michael Press -
Michael Press said:
It seems to me that tubes do not fail, typically.
Joints fail.
* down tube -- head tube.
* down tube -- braze on.
* any tube -- bottom bracket.
* chain stay -- drop out
* chain stay -- brake bridge
* seat stay -- seat tubeno tubes, no joints
--
/Marteninfo(apestaartje)m-gineering(punt)nl
-
Quoted message said:
M-gineering said:
Rik O'Shea said:
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)--
/Marteninfo(apestaartje)m-gineering(punt)nl
Well, about 30% stiffer laterally, and way stiffer vertically
depending on the geometry.10 points.
Quoted message said:
The question is, why double the top tube?
The down tube makes much more sense.a bigger diameter down tube and a triangulating [as opposed to parallel]
second top tube makes more sense still.
Active in the last 60 minutes
Active in this thread
0 users · 0 guests ·0 bots ·0 total
No signed-in users are active right now.
No known search crawlers active right now.