Truss instead of tube in bicycle frame?

John Thompson wrote:

Actually, bikes *ARE* built that way; just not a large volume of them.

The only one I've ever seen is a Moulton -- which are interesting but pointless.

I suspect that manufacturing costs of a truss frame are more likely
to be the reason why we don't see many of them on the road. There
are *MANY* more joints to deal with on a trust frame than on a simple
diamond frame, and all those joints take time to prepare (cutting,
mitering, cleaning) and join (braze/weld/whatever) than the three
main joints on a diamond frame.

This is true, but I still think the reason we don't see them is the design
presents no advantage. If it did, radiologists would be lining up to pay $6000
for them, or whatever it took.

Matt O.

In article ,
John Thompson wrote:

On 2004-10-20, Ryan Cousineau wrote:

Well, the Trek Y-foil disagrees with you. It was a UCI-legal aero
design, but was discontinued after a rule change made it illegal
(mandatory seat tubes, dontcha know):

Some of the UCI rules are pretty arbitrary. I remember when we built
track bikes for a US Women's team to compete in the World's back in 1984,
we had to rush to build new frames for them because the ones we had built
for them to use in North America turned out to be non-UCI compliant. Many
of the frames were quite small (54cm) and did not meet the UCI requirement
of a 55cm front-center measurement (distance from the center of the front
axle to the center of the BB spindle). We replaced them with frames that
did comply with this requirement, but they didn't fit the riders as well
as the ones we had designed for their body measurements.

In the future, you may want to check on that. The UCI has a rule (I'm
not going to look it up) that permits "morphological exceptions", which
essentially means that tall and short riders are allowed to have bikes
that fit them, as long as they are in the spirit of the rules.

--
Ryan Cousineau, http://www.wiredcola.com
Verus de parvis; verus de magnis.

"Matt O'Toole" writes:

Tim McNamara wrote:

"Matt O'Toole" writes:

Moultons may be intersting, but only as a design exercise. If
they were really that good, they and their imitators would be
everywhere. After all they've had 40 years to do it.

Well, the Moulton patents prevent duplication.

They're still in effect?

The patents on the technologies used in the New Series bikes (e.g.,
the Flexitor front suspension links, which in turn were based on a
suspension developed for the British military by Moulton) are still in
effect- only a few years old, actually. The original suspension
system was complex enough that probably no one would want to try to
duplicate it. The Brompton rear suspension is fairly similar to the
Moulton Type III rear suspension- indeed, all elastomer rear
suspensions (non-Horst link) are pretty similar to the Moulton Type
III.

But the principle of suspended small wheeled bikes is flourishing-
the Brompton, Birdy, Airnimal coming to mind readily. Not to
mention the 800 pound gorilla of small wheel bikes in the US, Bike
Friday.

Actually, the 800 LB gorilla is Dahon, which outsells all these
brands put together in the US, and before long probably everywhere
else. They're doing a great job coming out with new products, and
improving them along the way. IMO, the only folder company that has
anything special to offer over Dahon is Brompton, which is still the
smallest, easiest folder for bus/train/etc. It's probably only a
matter of time before Dahon is eating their lunch too.

Not in the performance market- at least not yet, although Dahon has
made some serious inroads in the past couple years- but you're correct
in that Dahon's sales probably exceed the entire rest of the folding
bike industry combined. If Dahon has a problem, it's that they spawn
and eliminate models like Apple did in the Gil Amelio days.

"Matt O'Toole" writes:

John Thompson wrote:

Actually, bikes *ARE* built that way; just not a large volume of
them.

The only one I've ever seen is a Moulton -- which are interesting
but pointless.

No, not pointless. The small, suspended wheel design has some merit.
People find them very pleasant for both short and long rides,
including around-the-world tours. They've been used successfully in
racing against "regular" bikes and in HPV record attempts. I'm
surprised Doug Milliken hasn't jumped in, since he knows as much about
Moultons as anyone except perhaps Sir Alex.

I suspect that manufacturing costs of a truss frame are more likely
to be the reason why we don't see many of them on the road. There
are *MANY* more joints to deal with on a trust frame than on a
simple diamond frame, and all those joints take time to prepare
(cutting, mitering, cleaning) and join (braze/weld/whatever) than
the three main joints on a diamond frame.

This is true, but I still think the reason we don't see them is the
design presents no advantage. If it did, radiologists would be
lining up to pay $6000 for them, or whatever it took.

Well, they are. Moulton apparently sells every bike it can make and
demand exceeds sales. I think US$6000 is lowballing the price.

I think the question is whether the design presents a *compelling*
advantage. At least in my case, it does not. I've ridden several
Moulton F frames and several AMs, and the ride is very nice indeed. I
have a Birdy which has a very similar ride, but rarely use it because
it attracts so much attention (I am 6'4"/215 lbs and look a little
strange on a bike at the best of times, but especially so on a bike
with wheels only a little bigger across than my shoes are long). If
the ride was vastly better, I'd ride it more. The folding is handy,
though.

Tim McNamara wrote:

"Matt O'Toole" writes:

Tim McNamara wrote:

"Matt O'Toole" writes:

Moultons may be intersting, but only as a design exercise. If
they were really that good, they and their imitators would be
everywhere. After all they've had 40 years to do it.

Well, the Moulton patents prevent duplication.

They're still in effect?

The patents on the technologies used in the New Series bikes (e.g.,
the Flexitor front suspension links, which in turn were based on a
suspension developed for the British military by Moulton) are still in
effect- only a few years old, actually. The original suspension
system was complex enough that probably no one would want to try to
duplicate it. The Brompton rear suspension is fairly similar to the
Moulton Type III rear suspension- indeed, all elastomer rear
suspensions (non-Horst link) are pretty similar to the Moulton Type
III.

It sounds like the patent is about suspension, not trussing (which is hardly
surprising). I have not followed the thread closely, but in a quick perusal I
did not note a discussion regarding cost. I wonder if all the trussing with all
the tubings special bends, and the additional but necessary weld and/or brazing
joints don't increase the cost quite a bit. The reason trussing may not be seen
in bicycles may be cost rather than technical. In any case, it would seem that
the more simplistic standard diamond frame (two triangles, where truss design
has many more triangles) has sufficient rigidity/strength. As "simple as
possible" for the given purpose is the Ockham's razor of engineering. There is
no reason to assume that diamond frames have not dominated for over 100 years
for very pracitcal reasons.

The question would have to be: is trussing worth it? I think the absence says
it is not worth it in the mass market. Perhaps for very large frames (long
spans) and very heavy duty service the truss might be more practical. But
"trussings" absence in the mass market is conspicuous.

gwhite wrote:

In any case, it would
seem that the more simplistic standard diamond frame (two triangles,
where truss design has many more triangles) has sufficient
rigidity/strength. As "simple as possible" for the given purpose is
the Ockham's razor of engineering.

Ultimately, I think this is it.

Matt O.

On Wed, 20 Oct 2004 16:58:27 -0700, Ryan Cousineau
wrote:

In article ,
"Matt O'Toole" wrote:
snip

Well, the Trek Y-foil disagrees with you. It was a UCI-legal aero
design, but was discontinued after a rule change made it illegal
(mandatory seat tubes, dontcha know):

http://www.chainreaction.com/Y-Foil.htm#Nomoreyfoils

snip

This design was killed because of racing? Do people really pay
attention to that?

Michael J. Klein
Dasi Jen, Taoyuan Hsien, Taiwan, ROC
Please replace mousepotato with asiancastings
---------------------------------------------

In article ,
Michael J. Klein wrote:

On Wed, 20 Oct 2004 16:58:27 -0700, Ryan Cousineau
wrote:

In article ,
"Matt O'Toole" wrote:
snip

Well, the Trek Y-foil disagrees with you. It was a UCI-legal aero
design, but was discontinued after a rule change made it illegal
(mandatory seat tubes, dontcha know):

http://www.chainreaction.com/Y-Foil.htm#Nomoreyfoils

snip

This design was killed because of racing? Do people really pay
attention to that?

With bikes specifically designed for racing, they do.

More particularly, the Y-Foil's core market was surely time triallists,
though I assume a fair number of riders bought them just because they
were neat, with no competition intentions (hey, it would be the coolest
bike on the charity ride...). Once they had no incentive to buy the
bike, nobody really wanted the machine.

The Y-foil was a fine design, but didn't have any particular merit aside
from aerodynamics, and I suspect (without checking) it was heavier than
conventional designs.

--
Ryan Cousineau, http://www.wiredcola.com
Verus de parvis; verus de magnis.

John Thompson Wrote:
On 2004-10-20, Ryan Cousineau wrote:

Well, the Trek Y-foil disagrees with you. It was a UCI-legal aero
design, but was discontinued after a rule change made it illegal
(mandatory seat tubes, dontcha know):

Some of the UCI rules are pretty arbitrary. I remember when we built
track bikes for a US Women's team to compete in the World's back in
1984,
we had to rush to build new frames for them because the ones we had
built
for them to use in North America turned out to be non-UCI compliant.
Many
of the frames were quite small (54cm) and did not meet the UCI
requirement
of a 55cm front-center measurement (distance from the center of the
front
axle to the center of the BB spindle). We replaced them with frames
that
did comply with this requirement, but they didn't fit the riders as
well
as the ones we had designed for their body measurements.

--

-John )

The front-center min was not all that arbitrary-deliberately designed.
Following Frances Faure's domination on a recumbent, that was one of the
minimum dimensions UCI legislated in 1934 to keep recumbent-like aero
bikes out of competition:

http://www.bikepathoutfitters.com/bent_history.htm


--
meb

On Sat, 23 Oct 2004 10:32:15 +0800, Michael J. Klein
wrote:

On Wed, 20 Oct 2004 16:58:27 -0700, Ryan Cousineau
wrote:

In article ,
"Matt O'Toole" wrote:
snip

Well, the Trek Y-foil disagrees with you. It was a UCI-legal aero
design, but was discontinued after a rule change made it illegal
(mandatory seat tubes, dontcha know):

http://www.chainreaction.com/Y-Foil.htm#Nomoreyfoils

snip

This design was killed because of racing? Do people really pay
attention to that?

Apparently they do. All over this sport you see people basing their equipment,
training and even nutritional decisions on what's effective or required for
racing, even though that is not what they do.

Ron