Monotubes vs Triangulation

Alan Mushnick said:

Isn't there an inherent structural advantage of
triangulated frames over monotubes? This seemed to be a
big part of the discussion of the Easy Racer vs. Rans
V2 debate.

Both the Easy Racers Tour Easy/Gold Rush Replica/TiRush and
the RANS Velocity Squared/Formula have triangulated frames.

RANS Force 5 versus the Bacchetta Strada and Corsa would be
a more apt comparison.

I do not know what a "Rans" is, so I can not comment on it.

--
Tom Sherman – Quad Cities (Illinois Side)

Tom, "Rans" is the company that denies the seat
problems ,once this is resolved it will again become
"RANS" 🙂 Ben fox

"Tom Sherman" <[email hidden]> wrote in message -"]news:[email hidden]-
berlin.de...

Quoted message said:

Alan Mushnick said:

Isn't there an inherent structural advantage of
triangulated frames over monotubes? This seemed to be a
big part of the discussion of the Easy Racer vs. Rans V2
debate.

Both the Easy Racers Tour Easy/Gold Rush
Replica/TiRush and the RANS Velocity Squared/Formula
have triangulated frames.

RANS Force 5 versus the Bacchetta Strada and Corsa would
be a more apt comparison.

I do not know what a "Rans" is, so I can not comment on
it.

--
Tom Sherman – Quad Cities (Illinois Side)

"Alan Mushnick" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Isn't there an inherent structural advantage of
triangulated frames over monotubes?

I think there is typically a weight penalty to make the
monotube as strong and stiff as a triangulated or "space"
frame. The Lightning P 38 and Phantom would be a good
example of this. My guess is that the Phantom monotube frame
is about 10% to 15% heavier than the P 38 frame with the
same geometry and size.

skip

[QUOTE]Originally posted by Ben Fox
[B]Tom, "Rans" is the company that denies the seat
problems ,once this is resolved it will again become
"RANS" 🙂 Ben fox

"Tom Sherman" <[email hidden]> wrote in message -"]news:[email hidden]-
berlin.de...

Quoted message said:

Alan Mushnick said:

Isn't there an inherent structural advantage of
triangulated frames over monotubes? This seemed to be a
big part of the discussion of the Easy Racer vs. Rans V2
debate.

Both the Easy Racers Tour Easy/Gold Rush
Replica/TiRush and the RANS Velocity Squared/Formula
have triangulated frames.

RANS Force 5 versus the Bacchetta Strada and Corsa would
be a more apt comparison.

I do not know what a "Rans" is, so I can not comment on
it.

--
Tom Sherman – Quad Cities (Illinois Side) [/B]

Tom Sherman said:

I do not know what a "Rans" is, so I can not comment on it

Bald-headed guy in cartoon series. Flies on dinosaurs, I
think. Something like that.

Curtis L. Russell Odenton, MD (USA) Just someone on
two wheels...

All the comments so far have been dead on. It's best to
think of this in terms of compromise. Triangulation gives
you the best stiffness and strength for the amount of
material that you use. You can flip that around and use more
material to make a monotube frame every bit as stiff and
strong, but it will weigh a lot more. (The old "if black
boxes always survive the airplane crash, then why aren't
airplanes built like black boxes?" thing.)

This is why the Catrike frames are triangulated...it lets us
build a much lighter frame without sacrificing strength or
stiffness. Frames that are not triangulated must by
definition be heavier in order to carry the required loads
and not be too flexible. This is the biggest reason why non-
triangulated trikes weigh so much more.

Note that tubing shape and size also come into play. The
greater the diameter of the tube, the stiffer it is. Look at
the the fat-tube Cannondale DFs... the fat tubes are
necessary because aluminum is not as inherently stiff as
steel, so you need to compensate by using fatter, somewhat
heavier tubes...more compromise. Bacchetta's egg-shaped tube
is stiffer in the vertical direction than it is laterally.
This lets them get the stiffness of a much larger tube in
the direction where the most loading is, without using the
larger tube. So, a little bit of weight is saved.

Box sections are stiffer than round tubes when it comes to
bending, but not as resistant to torsional (twisting)
forces. This is why George Reynolds gave the early Wishbones
a box shape. I had a Wishbone Classic and it was incredibly
stiff. (He made it out of folded sheet CrMo, not heavy drawn
tubing...so it was also quite light.)

Note also that a typical triangulated bike frame like the
Easy Racers is triangulated in only one plane (the vertical
one). Laterally, it's just a collection of tubes laid down
next to one another. It will be enormously stiff and strong
in that vertical plane, but not nearly as stiff or strong in
the lateral direction. I'd bet that the V2 frame is actually
stiffer and stronger laterally than the Easy Racers frame,
because the main tube is larger (therefore stiffer in all
directions) and the brace tubes are offset from the
centerline, which gives it triangulation in three
dimensions.

Andy Douglas Catrike

Andrew Douglas said:

Note also that a typical triangulated bike frame like the
Easy Racers is triangulated in only one plane (the
vertical one).

Not quite. The lower tube on the Tour Easy and Gold Rush
bikes is actually two tubes side by side, about 1cm apart,
all the way from the bottom bracket to the rear wheel. That
makes it very stiff laterally.

TY for pointing that out so I didn't have to 🙂

Gabe

"Joao de Souza" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Andrew Douglas said:

Note also that a typical triangulated bike frame like
the Easy Racers is triangulated in only one plane (the
vertical one).

Not quite. The lower tube on the Tour Easy and Gold Rush
bikes is actually two tubes side by side, about 1cm apart,
all the way from the bottom bracket to the rear wheel.
That makes it very stiff laterally.

[email hidden] (Andrew Douglas) wrote in message news:<[email hidden]>...

Quoted message said:

All the comments so far have been dead on. It's best to
think of this in terms of compromise. Triangulation gives
you the best stiffness and strength for the amount of
material that you use. You can flip that around and use
more material to make a monotube frame every bit as stiff
and strong, but it will weigh a lot more. (The old "if
black boxes always survive the airplane crash, then why
aren't airplanes built like black boxes?" thing.)

This is why the Catrike frames are triangulated...it lets
us build a much lighter frame

Are you really serious here? A trike as a speed bike
compared to a bike like the Bacchetta Aero? My Aero is 22
lbs. Pretty light for a 'bent. And The flex thing is not a
big deal for a person who can spin. I weigh in at 155 lbs
and am probably not the typical recumbent rider. I find that
the Aero Monotube design is both simple and stiff enough and
a great bike for all day rides. Lets see RANS sponsor some
riders like Bacchetta does and let them come to places like
Monkey Island or some of the other race venues! More 'bent
[censored] and it never seems to end.

And, Trikes are a joke as far as speed machines go and I
know the fat old guys will jump on this one! Don't get me
wrong trikes are cool and I like some of the neat designs
out there but don't go telling people that they are the
cutting edge in bent speed design. The fastest unfaired
bikes only have two wheels. Sorry to burst the FOG's bubble.

"meb" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

A monotube is lighter weight since only a single tube is
involved and it is more flexible giving a built in
suspension. But it lacks the support available from a
triangulated truss. For a strong heavy flexible metal such
as chromoly steel this is often the best bent frame
structure since it saves weight and lets the steel flex.

The triangulated Rans Force5 frame is noticeably lighter
than the steel monotube hiracer frames on the market.

"Gabriel DeVault" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

TY for pointing that out so I didn't have to 🙂

Sorry about that...I remembered that fact right after I hit
the "post" button.

Just to clarify, I didn't mean to imply that the TE frame
(or any other conventional safety bicycle-type frame) is
weak laterally...far from it. Only that plane trusses are
very stiff and strong in the direction in which they're
triangulated, but less so at right angles to that plane.
Even with the pair of side-by-side lower tubes, the TE frame
is going to be stiffer and stronger in one plane than it is
in the other. To make a bicycle frame as stiff and strong
laterally as it is vertically, you'd have to build a space
frame as wide as it is tall.

The basic design of the diamond-frame bicycle (which the TE
is an extension of) has proven itself to be very robust over
many, many years. It's a really elegant way of solving the
design problem...much more efficient in terms of use of
materials than a plain monotube. So relative differences in
strength and stiffness in one plane vs. the other are really
academic: the thing is plenty strong enough.

The TE's side-by-side lower tubes are (please correct me if
I'm wrong...I don't own one) literally side-by-side and not
separated, which if I understand the forces involved would
make them behave approximately like a single oval tube of
similar dimension to the two together...stiffer in the
direction of the major axis than it is in the direction of
the minor axis.

I believe (not entirely sure about this) that the overall
dimensions of the truss directly impact its stiffness and
strength. So, for example, a wide truss (TE frame) will be
stronger and stiffer in the vertical dimension than a narrow
truss (V2 frame) if all else is equal (similar tube sizes
and materials). RANS uses a fat main tube, so that changes
things, making the narrow truss stronger and stiffer (and
heavier) than it would otherwise be. The V2's lower tubes
are separated and braced, which adds to the lateral
stiffness.

Of course, I may be completely out of my skull. Wouldn't be
the first time. ;-)

Please feel free to correct me if I'm wrong.

Andy Douglas Catrike

"nogoslow" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Are you really serious here? A trike as a speed bike
compared to a bike like the Bacchetta Aero? My Aero is 22
lbs. Pretty light for a 'bent. And The flex thing is not a
big deal for a person who can spin. I weigh in at 155 lbs
and am probably not the typical recumbent rider. I find
that the Aero Monotube design is both simple and stiff
enough and a great bike for all day rides. Lets see RANS
sponsor some riders like Bacchetta does and let them come
to places like Monkey Island or some of the other race
venues! More 'bent [censored] and it never seems to end.

Randy designed a triangulated steel hiracer frame that is
much lighter than the Strada/Corsa frame.

I don't get your insistence on "sponsoring riders". We can
all ride and compare bents at our nearest dealers.

Alan Mushnick wrote;

Quoted message said:

Isn't there an inherent structural advantage of
triangulated frames over monotubes? This seemed to be a
big part of the discussion of the Easy Racer vs. Rans
V2 debate.

Hi Alan

Designers make choices all the time about how to balance
the sometimes conflicting goals of weight, stiffness,
aerodynamics etc. of frames.

Many times frame geometry and material, or the style of
bike (or trike) and wheelbase make the designers
choices easy.

Two entirely different stiffness issues are involved
here, those against pedaling forces (fairly important
IMO) and vertical stiffness. I have ridden truss
frames out there that are very vertically stiff, but
have wagging/twisting bottom brackets from a lack of
horizontal stiffness. Pedaling forces act on frames in
both the horizontal and vertical plane.

Vertical stiffness is not always a good thing on
bicycles, you have to consider that you have a human
engine on board, and bumpy roads to contend with. If a
frames stiffness against pedaling forces also makes the
frame a jackhammer vertically, you only have the tires
and the seat cushioning to act as springs between you
and the road.

Also, making a frame lighter by triangulation can make
a bike slower by increasing the frontal area of tubes
under the rider, and also by requiring lower pressure
(generally wider, heavier, lower performance) tires
for equivalent rider comfort. A bikes frontal area and
the tires rolling resistance are the two dominant
factors in efficiency on most courses.

Weight undoubtedly sells bikes- but improved
aerodynamics and lower rolling resistance makes them
more efficient on the road.

As far as triangulation always yielding lighter
frames... the bare titanium Bacchetta Aero frame weighs
3.5 lbs and has what I feel are the ideal tradeoffs of
weight, low frame frontal area under the rider, and
some passive suspension vertically...but still stiff
enough against pedaling forces for high transmission
efficiency.

Our steel frames weigh about 3 lbs more and are stiffer
vertically, but still have a good amount of passive
suspension to augment the tires and seat cushioning's
road shock absorbtion...VERY important to our bikes
performance!

That's what is great about the world of recumbents
today, everyone can make a different choice about what
is most important to them, and choose bikes with
greatly different characteristics and abilities!

Rich Pinto
Bacchetta Bicycles

Andrew Douglas said:

The TE's side-by-side lower tubes are (please correct me
if I'm wrong...I don't own one) literally side-by-side and
not separated,

I'm not 100% sure about the TE, but on the GRR they are
separated. Its two tubes, about 1cm in diameter each and
with a 1cm gap between them. They are joined at the bottom
bracket, and have a few supporting beams welded to it
along the way.

Great post Rich, You always do a great job of explaining
your position. Obviously you prefer Bacchetta bikes but you
state that in such a way you don't trash your competitors.

"RCPINTO" <[email hidden]> wrote in message news:20040416105652.17588.00000351@mb-
m20.aol.com...

Quoted message said:

Alan Mushnick wrote;

Quoted message said:

Isn't there an inherent structural advantage of
triangulated frames over monotubes? This seemed to be a
big part of the discussion of the Easy Racer vs. Rans V2
debate.

Hi Alan

Designers make choices all the time about how to
balance the sometimes conflicting goals of weight,
stiffness, aerodynamics etc. of frames.

Many times frame geometry and material, or the style
of bike (or

trike) and

Quoted message said:

wheelbase make the designers choices easy.

Two entirely different stiffness issues are involved
here, those

against

Quoted message said:

pedaling forces (fairly important IMO) and vertical
stiffness. I have

ridden

Quoted message said:

truss frames out there that are very vertically stiff, but
have wagging/twisting bottom brackets from a lack of
horizontal stiffness.

Pedaling

Quoted message said:

forces act on frames in both the horizontal and
vertical plane.

Vertical stiffness is not always a good thing on
bicycles, you have

to

Quoted message said:

consider that you have a human engine on board, and bumpy
roads to contend with. If a frames stiffness against
pedaling forces also makes the frame

a

Quoted message said:

jackhammer vertically, you only have the tires and the
seat cushioning to

act

Quoted message said:

as springs between you and the road.

Also, making a frame lighter by triangulation can
make a bike slower

by

Quoted message said:

increasing the frontal area of tubes under the rider,
and also by

requiring

Quoted message said:

lower pressure (generally wider, heavier, lower
performance) tires for equivalent rider comfort. A bikes
frontal area and the tires rolling resistance are the two
dominant factors in efficiency on most courses.

Weight undoubtedly sells bikes- but improved
aerodynamics and lower rolling resistance makes them
more efficient on the road.

As far as triangulation always yielding lighter frames...
the bare
titanium Bacchetta Aero frame weighs 3.5 lbs and has what I
feel are the

ideal

Quoted message said:

tradeoffs of weight, low frame frontal area under the
rider, and some

passive

Quoted message said:

suspension vertically...but still stiff enough against
pedaling forces for

high

Quoted message said:

transmission efficiency.

Our steel frames weigh about 3 lbs more and are
stiffer vertically,

but

Quoted message said:

still have a good amount of passive suspension to augment
the tires and

seat

Quoted message said:

cushioning's road shock absorbtion...VERY important to
our bikes

performance!

Quoted message said:

That's what is great about the world of recumbents
today, everyone

can

Quoted message said:

make a different choice about what is most important to
them, and choose

bikes

Quoted message said:

with greatly different characteristics and abilities!

Rich Pinto
Bacchetta Bicycles

Ted said:

Great post Rich, You always do a great job of explaining
your position. Obviously you prefer Bacchetta bikes but
you state that in such a way you don't trash your
competitors.

I agree. A clear explanation of what he perceives to be
the best choice among several alternatives, and all
without coming across as simply biased and against the
designs of the other bikes. The combination results in a
great deal of credibility, not to mention cravings for
the bikes in question!
--
Larry Varney Cold Spring, KY
home.fuse.netlarryvarneyOpen ↗

(nogoslow) said:

Are you really serious here? A trike as a speed bike
compared to a bike like the Bacchetta Aero? ... Don't get
me wrong trikes are cool and I like some of the neat
designs out there but don't go telling people that they
are the cutting edge in bent speed design.

Huh? I neither said nor implied any such thing!!! Did you
even read the post? I didn't say the Catrikes are "cutting
edge in bent speed design," nor did I compare its speed with
any bicycle. For that matter I said nothing about the speed
of anything. Just where did you get that idea?

All I said was that trangulated structures are stiffer and
stronger for the amount of material used than monotube
structures. That goes for bridges and buildings and radio
towers and the Eiffel Tower as well as bicycles. Regarding
the Catrike reference, ALL I said was that we can use
lighter/less material to get the required degree of
stiffness and strength because it's triangulated. If we
built a non-braced frame, we'd have to build it heavier to
get the same properties. That doesn't mean we couldn't make
it just as strong and just as stiff...we'd just have to
trade weight in order to do that. The same goes for any
other manufacturer of any design. We're not special.

I also said NOTHING WHATSOEVER about monotube structures not
being strong enough. Of course they are strong enough if
designed properly!

But if you take the same mass of titanium that's in your
Aero and build a triangulated truss out of it, it will be
stiffer and stronger than the monotube is. That's NOT THE
SAME THING as saying that the Aero isn't stiff enough and
strong enough to begin with. It also does not mean that a
triangulated structure will necessarily achieve the intended
design goals. As Rich pointed out, when you start hanging
all those tubes out in the breeze you have other things to
think about (aerodynamics, etc.).

Triangulation is simply another way of solving the design
question. It's not inherently "better" or "worse." It's
DIFFERENT. It's a design tool, nothing more.

I'll gladly retract any incorrect statements I make, but
geez, PLEASE don't go putting words in my mouth!

Andy Douglas Catrike

Quoted post said:

Originally posted by Timh

The triangulated Rans Force5 frame is noticeably lighter
than the steel monotube hiracer frames on the market.

Volae Sport 27.5 vs. Force 5 LE 28.0-28.4
Volae Club 26 (No intermediate Force 5 model)
Volae Team 24 vs. Force 5 XP 25.6-25.9

Are you suggesting the Volae models save weight with much lighter componetry?

I am a newbie to bent riding after many thousands of miles
on wedges. I am not an expert in cycling architecture, but
after a couple of hundred miles on my Corsa, it seems like a
great balance between pedaling efficiency and vertical
compliance. I really enjoy the feel of the input through the
pedals and the way in which the bike flexes over the common
undulations in the road. More abrupt bumps, of course, are a
real pain in the butt, but overall, what a nicely engineered
mono tube bike structure. I'm amazed at the the fine tuned
engineering of my Bacchetta.

[email hidden] (RCPINTO) wrote in message news:<20040416105652.17588.00000351@mb-
m20.aol.com>...

Quoted message said:

Alan Mushnick wrote;

Quoted message said:

Isn't there an inherent structural advantage of
triangulated frames over monotubes? This seemed to be a
big part of the discussion of the Easy Racer vs. Rans V2
debate.

Hi Alan

Designers make choices all the time about how to
balance the sometimes conflicting goals of weight,
stiffness, aerodynamics etc. of frames.

Many times frame geometry and material, or the style
of bike (or trike) and wheelbase make the designers
choices easy.

Two entirely different stiffness issues are involved
here, those against pedaling forces (fairly
important IMO) and vertical stiffness. I have ridden
truss frames out there that are very vertically
stiff, but have wagging/twisting bottom brackets
from a lack of horizontal stiffness. Pedaling forces
act on frames in both the horizontal and vertical
plane.

Vertical stiffness is not always a good thing on
bicycles, you have to consider that you have a human
engine on board, and bumpy roads to contend with. If
a frames stiffness against pedaling forces also makes
the frame a jackhammer vertically, you only have the
tires and the seat cushioning to act as springs
between you and the road.

Also, making a frame lighter by triangulation can
make a bike slower by increasing the frontal area of
tubes under the rider, and also by requiring lower
pressure (generally wider, heavier, lower
performance) tires for equivalent rider comfort. A
bikes frontal area and the tires rolling resistance
are the two dominant factors in efficiency on most
courses.

Weight undoubtedly sells bikes- but improved
aerodynamics and lower rolling resistance makes them
more efficient on the road.

As far as triangulation always yielding lighter
frames... the bare titanium Bacchetta Aero frame
weighs 3.5 lbs and has what I feel are the ideal
tradeoffs of weight, low frame frontal area under the
rider, and some passive suspension vertically...but
still stiff enough against pedaling forces for high
transmission efficiency.

Our steel frames weigh about 3 lbs more and are
stiffer vertically, but still have a good amount of
passive suspension to augment the tires and seat
cushioning's road shock absorbtion...VERY important
to our bikes performance!

That's what is great about the world of recumbents
today, everyone can make a different choice about
what is most important to them, and choose bikes with
greatly different characteristics and abilities!

Rich Pinto
Bacchetta Bicycles