Hypothetical Frame Question

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

Dear John,

Several answers are likely.

A) You'd need an accelerometer to measure the vibrations. Here's a
post with some links to accelerometer results that claim Specialized
frames reduce vibration:

http://groups.google.com/group/rec.bicycles.tech/msg/d6903803e6a3ce50

Many people argue quite reasonably that the tires, handlebar tape,
gloves, shoes, socks, and seat would mask any differences in how the
metal frames transmit vibrations.

On the other hand, wood, aluminum, titanium, and composite baseball
bats show very different behavior when they whomp leather-covered
chunks of yarn wound around rubber centers:

http://www.kettering.edu/~drussell/bats-new/compalum.html

B) But with identical dimensions, the steel frame would be heaviest
and thus damp vibrations more.

C) Building frames with identical dimensions out of different
materials defeats the point of using different materials. Aluminum
frame tubes are larger for a reason.

D) The rear wheel isn't likely to move much closer to the seat, given
the rear frame's strength in the vertical plane. But how much the
frame-and-front-fork flex may have a perceptible effect. Back to A),
where accelerometers can shed more light on the question.

E) Some of us treat this as an enjoyable academic exercise, but can't
really imagine noticing the difference. It's been claimed that the
surface of my daily ride is badly weathered:

http://home.comcast.net/~carlfogel/download/047_spot_the_goathead.jpg

And I admit that there are a few hundred cracks per mile:

http://home.comcast.net/~carlfogel/download/038_goatheads_in_crack.jpg

But I'm used to these surfaces and happily run 120-125 psi at 20-25
mph.

The only time that I notice a ride problem is when I drift over onto
the rumble strip. I doubt that any frame would make that mistake
pleasant.

Cheers,

Carl Fogel

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

The one with the largest useable tires inflated to the lowest practical
pressure?

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

Those materials shouldn't be built to the same specs as they have very
different properties. Any one should be plenty comfy if built right.
I'd ridden more overbuilt and jarring aluminum bikes, but I've owned
one that rode smooth as can be.

So the most comfortable frame would be the one that fits right and has
some supple tires. Skinwalls will generally ride nicer than gumwalls or
other thick sidewalls.

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

The question isn't useful. If you built an aluminum frame with the same
diameters and wall thicknesses as an average steel (say chromoly,
because thicknesses vary quite a bit among different steel tubes)
frame, it wouldn't function as a frame. If you built a chromoly frame
with the same diameters and thicknesses as an average aluminum frame,
it would be the stiffest, heaviest bike frame you ever saw.

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

if you were to build an infinitely stiff frame it would ride about the
same as a "real" frame. in the absence of suspension with macroscopic
travel, comfort is a function of components, fit and geometry.

JS said:

Quoted message said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

I would ask it this way:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of size and geometry with all other things being
equal, i.e. built around the exact same wheels, components and tires,
all running the same pressure, which frame would be the most
comfortable to ride?

In article
<[email hidden]>,

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

The __________ frame will be more plush and responsive.

Such frames will not tell you anything. Build frames with
tubing sized for the particular material. Steel, aluminum,
and titanium have different bulk properties. Al frames
typically have larger diameter tubes than steel, for
instance.

--
Michael Press

In article
<[email hidden]>,

landotter said:

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

Those materials shouldn't be built to the same specs as they have very
different properties. Any one should be plenty comfy if built right.
I'd ridden more overbuilt and jarring aluminum bikes, but I've owned
one that rode smooth as can be.

So it's true? That some Al frames were palpably different?
How do you characterize the ride, and what about the frame
design made it `harsh and jarring.' What makes a well
designed Al frame?

--
Michael Press

Nate Knutson said:

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

The question isn't useful. If you built an aluminum frame with the same
diameters and wall thicknesses as an average steel (say chromoly,
because thicknesses vary quite a bit among different steel tubes)
frame, it wouldn't function as a frame. If you built a chromoly frame
with the same diameters and thicknesses as an average aluminum frame,
it would be the stiffest, heaviest bike frame you ever saw.

The question was asked for a reason. Of course you can't build
different material frames to the same specifications. It was asked to
dispell the myth of frame comfort having anything to do with materials.
The question came up after some discussions I had with a friend who
adamantly believes that material is the determining factor for comfort.

Quoted message said:

From looking at the properties of the different materials, I'm guessing

that aluminum would be the softest and most comfortable and steel woul
be the least comfortable if we stick to the same wall thickness and
diameters. Would this be correct?

R Brickston said:

JS said:

Quoted message said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

I would ask it this way:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of size and geometry with all other things being
equal, i.e. built around the exact same wheels, components and tires,
all running the same pressure, which frame would be the most
comfortable to ride?

Okay. You stated the question much better than I did!

Michael Press said:

In article
<[email hidden]>,

landotter said:

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

Those materials shouldn't be built to the same specs as they have very
different properties. Any one should be plenty comfy if built right.
I'd ridden more overbuilt and jarring aluminum bikes, but I've owned
one that rode smooth as can be.

So it's true? That some Al frames were palpably different?
How do you characterize the ride, and what about the frame
design made it `harsh and jarring.' What makes a well
designed Al frame?

What makes a well designed frame is up to the individual riding it, but
one I had that was spectacularly harsh, was a city bike. Even with 35mm
tires you could really feel the road. On the other hand, it climbed
like a stallion, and had no wobble even with a huge load on the rack.

In my experience, the more money you pay for aluminum, the less
overbuilt and nicer riding it'll be--up to a point of course.

There are all sorts of ways to build aluminum, the ride characteristics
can be changed with butting, geometry, tube diameter, and even tube
shape. Best way to see if you like it, is to ride it.

I just sold an aluminum bike with fairly large tubes that were ovalized
at the headset and BB, and it was a great riding bike. Just sold it as
I wanted a change, not because it was a bad bike.

I've ridden nice and awful steel as well. The old cheap dept store
"gaspipe" frames are pretty harsh as well.

JS said:

Nate Knutson said:

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

The question isn't useful. If you built an aluminum frame with the same
diameters and wall thicknesses as an average steel (say chromoly,
because thicknesses vary quite a bit among different steel tubes)
frame, it wouldn't function as a frame. If you built a chromoly frame
with the same diameters and thicknesses as an average aluminum frame,
it would be the stiffest, heaviest bike frame you ever saw.

The question was asked for a reason. Of course you can't build
different material frames to the same specifications. It was asked to
dispell the myth of frame comfort having anything to do with materials.
The question came up after some discussions I had with a friend who
adamantly believes that material is the determining factor for comfort.

Quoted message said:

From looking at the properties of the different materials, I'm guessing

that aluminum would be the softest and most comfortable and steel woul
be the least comfortable if we stick to the same wall thickness and
diameters. Would this be correct?

It depends on what the tube specs are. Say we're talking about a
common, economical type of aluminum for bike frames, like 6061-T6. You
specify tubes with regards to that material's properties that allow the
frame to be reasonably strong. That frame, like all frames that are
reasonably strong, is basically not going to have any vertical
compliance at all. Strength and stiffness are related like that.

What happens if you replace the aluminum with steel or ti? It will be
really godamn heavy and still have no vertifcal compliace. Will it be
less comfortable due to being stiffer vertically? I don't think so but
don't really know. However, I do have a Surly Instigator with a rigid
fork, which may be about as close as it gets in terms of steel bikes
where speccing aluminum with the same tubing diameters and wall
thicknesses would yield a functional bike, and it's plenty comfortable
for me (it's set up able to be sat down on with full leg extension,
fyi). I've only ridden it with fat tires, but wouldn't expect it to be
unpleasant with skinnier ones.

R Brickston rb20170REMOVE.yahoo.com@ said:

JS said:

Quoted message said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

I would ask it this way:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of size and geometry with all other things being
equal, i.e. built around the exact same wheels, components and tires,
all running the same pressure, which frame would be the most
comfortable to ride?

Depends. If the tube walls and sizing were appropriate for steel, the
ti bike would be light, but VERY flexy and not much fun to ride. The
aluminum bike would be very light, but positively suicidal (subject to
catastrophic failure), therefore I would be very UNcomfortable riding
it.

If the walls and tube diameters were appropriate for aluminum, the
steel bike would be quite a bit heavier, as would the titanium bike.
The steel bike would be very stiff laterally, to the point it would be
a good choice for a virtual 800 pound gorilla. The ti bike would be
similar - still more than stiff enough for the biggest, strongest
rider, but not quite as stiff laterally.

And if you measured the bare frames in a lab, you'd see that there is
a difference in the vertical compliance... it's just that it wouldn't
mean squat when you mask it by bolting on a bunch of positively
squishy parts (tires, saddles, bars, bar tape).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

On Fri, 15 Sep 2006 21:06:31 -0700, Mark Hickey <[email hidden]>

Quoted message said:

R Brickston rb20170REMOVE.yahoo.com@ said:

JS said:

>If we were to build a steel, titanium and aluminum frame to the same
>exact specifications of wall thickness and tubing diameters, built
>around the same wheels and components, which frame would be the most
>comfortable to ride?

I would ask it this way:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of size and geometry with all other things being
equal, i.e. built around the exact same wheels, components and tires,
all running the same pressure, which frame would be the most
comfortable to ride?

Depends. If the tube walls and sizing were appropriate for steel, the
ti bike would be light, but VERY flexy and not much fun to ride. The
aluminum bike would be very light, but positively suicidal (subject to
catastrophic failure), therefore I would be very UNcomfortable riding
it.

If the walls and tube diameters were appropriate for aluminum, the
steel bike would be quite a bit heavier, as would the titanium bike.
The steel bike would be very stiff laterally, to the point it would be
a good choice for a virtual 800 pound gorilla. The ti bike would be
similar - still more than stiff enough for the biggest, strongest
rider, but not quite as stiff laterally.

And if you measured the bare frames in a lab, you'd see that there is
a difference in the vertical compliance... it's just that it wouldn't
mean squat when you mask it by bolting on a bunch of positively
squishy parts (tires, saddles, bars, bar tape).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

I think what he OP is aiming for are identically sized bikes, i.e
standover height, rake, tube lengths, etc. The frame tubing would be
of dimensions neccessary for each material to fabricate a frame for
the explicit size.

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

My vote is for the aluminum frame. Until it breaks, assuming it is
built with wall thicknesses suitable for steel and Ti. It would be very
squishy and most probably would have an automatic transmission where
gear changes would happen automatically based on how hard you push the
pedals. Kind of like a Vitus 979!

Joseph

JS said:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of wall thickness and tubing diameters, built
around the same wheels and components, which frame would be the most
comfortable to ride?

John

Must be getting colder where you are....

R Brickston rb20170REMOVE.yahoo.com@ said:

I think what he OP is aiming for are identically sized bikes, i.e
standover height, rake, tube lengths, etc. The frame tubing would be
of dimensions neccessary for each material to fabricate a frame for
the explicit size.

I dunno - we've answered that one about a hundred times a month around
here already... I figured it was just a new direction for the
discussion.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Nate Knutson said:

JS wrote:

Quoted message said:

Quoted message said:

Quoted message said:

From looking at the properties of the different materials, I'm guessing

that aluminum would be the softest and most comfortable and steel woul
be the least comfortable if we stick to the same wall thickness and
diameters. Would this be correct?

It depends on what the tube specs are. Say we're talking about a
common, economical type of aluminum for bike frames, like 6061-T6. You
specify tubes with regards to that material's properties that allow the
frame to be reasonably strong. That frame, like all frames that are
reasonably strong, is basically not going to have any vertical
compliance at all. Strength and stiffness are related like that.

What happens if you replace the aluminum with steel or ti? It will be
really godamn heavy and still have no vertifcal compliace. Will it be
less comfortable due to being stiffer vertically? I don't think so but
don't really know. However, I do have a Surly Instigator with a rigid
fork, which may be about as close as it gets in terms of steel bikes
where speccing aluminum with the same tubing diameters and wall
thicknesses would yield a functional bike, and it's plenty comfortable
for me (it's set up able to be sat down on with full leg extension,
fyi). I've only ridden it with fat tires, but wouldn't expect it to be
unpleasant with skinnier ones.

Actually, there might actually be a demonstrable difference in ride
quality in this one case - if you make the steel frame heavy enough,
it'll help the ride quality by increasing the sprung weight (that is,
a given size bump will deflect the tire that much less because there's
more weight pushing down on it).

I can remember testing this premise coming back from college in my
trusty old Pinto station wagon, loaded to the gunwales with all my
stuff. I had installed a headphone jack (1/4" of course), and was
wearing a pair of heavy, sealed Koss headphones. The combination of
eliminating all the squeaks and rattles, and of increasing the sprung
weight by 500 pounds resulted in a luxury car ride.

Well, maybe not from a prestige viewpoint... ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

"R Brickston" <rb20170REMOVE.yahoo.com@> wrote in message
news:[email hidden]...

Quoted message said:

On Fri, 15 Sep 2006 21:06:31 -0700, Mark Hickey <[email hidden]>

Quoted message said:

R Brickston rb20170REMOVE.yahoo.com@ said:

On 15 Sep 2006 12:41:14 -0700, "JS" <[email hidden]> wrote:
>
>>If we were to build a steel, titanium and aluminum frame to the same
>>exact specifications of wall thickness and tubing diameters, built
>>around the same wheels and components, which frame would be the most
>>comfortable to ride?

I would ask it this way:

If we were to build a steel, titanium and aluminum frame to the same
exact specifications of size and geometry with all other things being
equal, i.e. built around the exact same wheels, components and tires,
all running the same pressure, which frame would be the most
comfortable to ride?

Depends. If the tube walls and sizing were appropriate for steel, the
ti bike would be light, but VERY flexy and not much fun to ride. The
aluminum bike would be very light, but positively suicidal (subject to
catastrophic failure), therefore I would be very UNcomfortable riding
it.

If the walls and tube diameters were appropriate for aluminum, the
steel bike would be quite a bit heavier, as would the titanium bike.
The steel bike would be very stiff laterally, to the point it would be
a good choice for a virtual 800 pound gorilla. The ti bike would be
similar - still more than stiff enough for the biggest, strongest
rider, but not quite as stiff laterally.

And if you measured the bare frames in a lab, you'd see that there is
a difference in the vertical compliance... it's just that it wouldn't
mean squat when you mask it by bolting on a bunch of positively
squishy parts (tires, saddles, bars, bar tape).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

I think what he OP is aiming for are identically sized bikes, i.e
standover height, rake, tube lengths, etc. The frame tubing would be
of dimensions neccessary for each material to fabricate a frame for
the explicit size.

No he wasn't. Read his post at the top above. He was explicitly setting up
the problem to obtain a response that would focus on how the frame materials
would perform at the same tubing diameters and wall thicknesses.

Cal