base2 

Well, it is good to know that one single static property, in one single plane of a dynamic system is the end-all, be-all defining feature of the concept of "comfort." I consider myself schooled and will now throw away all of my steel, aluminum and carbon bikes. What a fool I was to percieve any differences in ride qualities or characteristics between any of them and translate that to comfort or performance.

Next time, I'm getting a $150 gas pipe WallyWorld special because clearly it is every bit as comfortable (as defined by vertical compliance of frame only) as my other bicycles of all manner of construction. It sure is a good thing I stopped in here to get all straightened out.















FWIW: The OP asked about the subjective differences of getting a smaller, better fitting frame. Not the specific merits of frame material on vertical compliance as it relates to "comfort." --Gotta luv BF <3

Trakhak

Why It’s Impossible For Steel Frames To Be More Comfortable Than Aluminium

From that page:

"There are very few tests that have measured the vertical deflection or 'comfort' of a bicycle frame by itself. That’s because experiments are almost always conducted using a seatpost inserted in a frame. After all, we don’t attach our seats directly to our top-tubes!In the 1990s, Bob Bundy did some deflection tests on four 80s road frames. These frames required between 7,158 and 14,316 newtons of force to flex the rear triangle just one vertical millimetre.

Let me put those numbers into context for you. A top carbon flex seatpost will deflect the same distance with just 69N force. That’s literally 100 to 200 times less force."

TC1's willingness to continue his efforts to educate is admirable. I rarely make the attempt any more. But, once more, here's my take on the subject:

The idea that bikes built of different materials differ in comfort arose, I believe, when Cannondale started selling affordable racing bikes with criterium geometry (their Crit series, with ultra-short wheelbase) in the late '80's. Before then, the only people who rode short-wheelbase road bikes were people like me, who raced on expensive mid-'80's Italian criterium-geometry bikes.

So when the Cannondale dealership where I worked started stocking the new Crit series bikes, they felt very familiar---same rocket-ship acceleration, same instant response for maneuvering in a pack. And exactly the same level of "comfort" (not really a word I'd apply to either the Italian steel bike or the Cannondale aluminum bike).

But most people buying the Crit series bikes had never ridden a criterium-geometry steel bike. Most were upgrading from some mid-level sport touring bike with a moderately long wheelbase. To many of those riders, the Crit Series bike felt fast---too fast, in handling terms---compared to the forgiving handling of their previous bike.

In my experience of riding high-end racing bikes since the early '60s, "comfort" equals wheelbase. Longer wheelbase equals more comfort, if that's what you're looking for. It's a crude but reliable measure. As with cars---longer wheelbase, more comfort.

All my bikes with a given wheelbase ride similarly. Frame material doesn't seem to matter. In fact, my favorite bike for all my rides (usually around 4 to 5 hours in length these days) is my fixed-gear Specialized Langster, with oversized aluminum frame and oversized aluminum straight-blade fork. I haven't ridden either of my remaining steel bikes (Reynolds 531 and 853) in 10 years at least.

Since there's no perceptible or measurable difference in comfort for a given wheelbase, all that matters to me is torsional and lateral compliance. The less, the better. As I say, I can't feel any difference in comfort between frame materials. But the difference in the tracking of the wheels and in resisting twisting forces through the handlebars is instantly obvious to me.

Steel bikes are fine. If you're looking for comfort, go for a bike with a sport-touring wheelbase. (They're now marketed as gravel bikes or endurance bikes, interestingly.) Me, I prefer a highly responsive bike, which is why I've switched to aluminum for my bike frames.

Fentuz

basically I either misunderstand what you are trying to explain or I fundamentally disagree.
as I said a frame will deform depending of the design (tube sizing, mounting/connecting point and material properties).
here is a basic final element simulation course using bike frame as an example:

solidworks and ansys will give similar results and yes, the frame deforms depending of the design…

now if you are trying to say the in many cases the frame flex is negligeable compared to the flex of the seatpost, stem, handlebar, fork, cranks then yes, it is most likely the case but this is not what i am reading from your posts.


edit: here is another thing by a licensed mechanical engineer

One Wheel

I'm saying that vibrations propagate, and are not limited to the materials in which they originate.

When one component vibrates it induces vibrations in all the other components connected to it, usually at different frequencies than the original vibration. Those vibrations may be amplified or damped, but they are transmitted to the other components. Vibrations are real, and you do feel them. The part that I don't know is whether having the handlebars vibrate at 430 hz and 514 hz and having the seat vibrate at 485 hz and 520 hz (numbers picked at random) will feel uncomfortable.

Eric F 

I tune my bike to A 440.

Trakhak

Please! A 432! (Hope I'm never stuck in an elevator with an A 432 flat-Earther.)

One Wheel

A 440 will also have harmonics at 220, 660, 880, 1320, 1760, etc. Depending on the natural frequency of any given component it may vibrate at any of those frequencies most strongly, or at an entirely different frequency. My hypothesis is that if, for example, the fundamental frequency of the "road buzz" is 440hz, and the natural frequency of the handlebars is 1320hz, then a steel or titanium frame will transmit and possibly amplify the 440hz buzz, but not the 1320hz buzz that would make the handlebars vibrate strongly. Carbon, and to a lesser extent aluminum, are more likely to vibrate at all related frequencies, this creating more perceived vibration.

Eric F 

I was rolling along with my buddy on his E 659 tuned bike. A guy came up behind us riding a C 523. I told him to move along. I don't ride with minors.

One Wheel

That's a major third, not a minor.

Eric F 

ACE is the Am triad. If I'm A, C is the minor 3rd.

One Wheel

My bad. CE is the major third, but you're right AC is minor. What would you do if a B rolled up? That sounds terrible.

Trakhak

Of course, aluminum and (especially) carbon are inherently superior at damping vibration. It's obvious if you flick your top tube with a fingernail; the steel tube (and, to a slightly lesser degree) the titanium tube will give a high-pitched "ping"; the aluminum will sound approximately as (un)resonant as an aluminum beer can; and the carbon tube will just "thunk."

One Wheel

Where does the acoustic energy from the damped vibration go? Some is lost as heat, some goes in to degrading the frame material, and some is converted into other, not necessarily audible, frequencies.

Trakhak

The point is that less-dense materials damp vibration more effectively than denser materials. Keeping the topic in the realm of bicycles, bike bells made of steel ring for an appreciable period of time; the sound of bells made of aluminum (there have been a few) dies far more rapidly.

One Wheel

It rings for longer because the vibrations aren't converted into other frequencies. On one level it would make sense that propagation of a single frequency (or smaller number of frequencies) would mean that the amplitude of those vibrations would be greater. On another level, my description of how vibration propagation between components of different natural frequencies is one plausible mechanism that would explain the subjective observations that have been made about the differences between frame materials.

If you can't explain how something works, do you dismiss it or try to figure out how to explain it? I prefer the latter.

TC1

I am not expressing my opinion here -- I am relaying scientific fact, that has been proven decades ago and repeatedly since. You can choose to pretend that those facts do not exist, if you like, but that will not make them disappear.

No one suggested that it is. But again, the energy input that discomforts riders occurs in the vertical plane.

Most riders do not turn the pedals while cornering, first of all. And turning the pedals is very much not mutually-exclusive with riding in a straight line, so your first sentence there does not make much sense.

Second, again, for not even the second time, lateral and torsional deflection affect the handling of a bicycle, but not the comfort perceived by the rider -- those are two different qualities.

TC1

You can dispose of whatever bikes the spirit possesses you to, but as I said at least once before, there are good reasons to buy carbon fiber bikes, and there are good reasons to buy steel bikes, and there are good reasons to buy aluminum bikes, and so forth and on. However, none of those reasons are "improved comfort", because the frame's material has no effect on that quality. Again, this was proven decades ago, regardless of whether or not you remain unaware.


No one ever said that no differences exist -- only that those differences are not caused by the material properties of the frame. They are caused first and foremost by the human brain, but ignoring that factor for a second, the contributions to rider comfort, in approximate descending order, are: tire air pressure and volume, seat post stiffness, fork construction, saddle construction, and handlebar construction.


This would be much funnier if you exhibited even the slightest ability to comprehend the topic.

Ibid.

Not only is the title of this thread "Carbon to Ti frame", but the first post concludes with "I know many claims about Ti is great for comfort, others said it is not much different than Aluminium because of close density/Young modulus etc. So although it is very subjective, what is people real life experience between Carbon and Ti?"

Did you, in fact, read any of the thread, or were you just unable to understand any of it?

TC1

Again, of course a bicycle frame will eventually deflect. Humans do not possess the capability to manufacture an object that is infinitely strong. The point is, a bicycle frame will not deflect in the vertical plane before any of the components attached to it.

You can, if you so choose, "fundamentally disagree" with science that has been established for decades, if you like -- but that just makes you wrong.

Yes, that is precisely what I have said, too many times to count. And it isn't "in many cases" or "most likely the case", it is always the case, and that has been proven, time and again, decades ago.

79pmooney

Just a data point here. I have a short wheel base, quite stiff (and not especially light, even by small tubed steel standards) early '80s Pro Miyata. Top of the line tubing but not thin or light. (Miyata home brew so I cannot tell you what it is. One of the Miyata company's branches is a serious steel mill. Probably a far bigger plant than the bikes.) I run a 25c tubular at 98 psi in front and a 23c at 110 in back. (On wonderful, compliant, totally old-school Mavic GP4 rims.) Short wheelbase and an upright geometry, vertically stiff frame.

I feel everything on the road. It has no damping. (The main tubes ring like clear, high quality bells only with simpler sounds. And I find the ride wonderful. (On pavement, not deep gravel but that's the skinny tires.) I rode the week long Cycle Oregon on it in September and loved it. I am quite certain that a bike of the same geometry but "dead" steel tubes would have made for a far less enjoyable week.

Fentuz

No you have been playing on words saying double triangle do not move and I kept saying it does. And yes, I am cautious with some statements hence "most likely the case" because I do not have hard data to make a clear cut decision.
For example saying a seatpost with bend before a frame is simply not true; if the seatpost is fully down because small rider, it won 't flex since the flex is the reaction to a load applied to a beam of a given shape, dimension and material properties.... So Yes, if it most likely to to flex or to be more accurate, it will flex when protruding but will not when fully down...

Fentuz

Frankly, did you?

I asked about frame and frame material ONLY as I will transfer everything from the current frame to the next. And yet you started to that it does not matter because flex and comfort come from the accessories ..

Trakhak

It does not matter, because the flex and comfort do come from the accessories---and from the tires and saddle, of course. If a seatpost is all the way down, that just means that it doesn't contribute its own shock absorption in addition to that provided by the saddle rails and top.

If anyone participating in this thread can provide any rebuttal beyond "Eppur si muove"---that is, can provide quantitative evidence that double-diamond metal bicycle frames (a) differ in vertical shock absorption between materials and (b) flex enough for that flex to be perceptible despite being swamped by, e.g., tire flex---please do so.

Passionate assertions and flowery descriptions of someone's bike with a magical ride are fun to read, but they're up against test results that have consistently shown that double-diamond metal bike frames are effectively perfectly rigid in the vertical plane. Those of you who "believe" otherwise, let's see the test results. Numbers, please. (That includes the speculations concerning interacting "vibrations" somehow affecting ride comfort---let's see the measured numbers.)

TC1

Now you are just being ignorant. From my very first comment in this thread:

There is no subjectivity to the question, either, it is a simple matter of physical properties -- a double-triangle frame will not deflect vertically before:

* your tires collapse onto the wheels and probably debead
* your seatpost deflects
* your saddle rails deflect
* your handlebar deflects
* your fork deflects
* your wheel deflects, probably to the point of permanent deformation
* all of the above ( not necessarily in that order )

Statements which I have repeated here numerous times. If you are unable or unwilling to understand those words, that is increasingly not my problem.

TC1

So what is your problem, then? You asked about frame material -- titling your thread "Carbon to Ti frame" and asking "I know many claims about Ti is great for comfort, others said it is not much different than Aluminium because of close density/Young modulus etc. So although it is very subjective, what is people real life experience between Carbon and Ti?"

I answered that question. You didn't get the answer that you wanted, and are now being petulant, as a result.

If you want to waste money trying to buy a comfortable frame, knock yourself out, it's your money. It won't work, but that's clearly not what you want to hear, so do whatever the hell you want.

TC1

You misunderstand the word "data". Your belief in an untested hypothesis is not any sort of data.

Literally all of the data that we possess tells us that your belief is unfounded, and that if you desire more comfort from that rig, you need to figure out how to stop running triple-digit tire pressures like it's 1970.

By the way, those rims are probably not as "compliant" as you think, since every study reveals wheels to be quite stiff vertically -- which is no surprise to anyone who understands how a spoked wheel works, or how much aluminum generally doesn't tolerate bending.