if i understand you to be talking about friction between the tube and the inside of the tire, okay, makes sense, but that sounds like a completely separate argument than hysteresis. as i understand it, hysteresis is a measurable value in tubeless tires, no?

how I understand it is when you compress something and there is a delay in return and maybe all of the energy input is not returned, that loss is hysteresis loss? maybe in a tube there is 2 types of loss, frictional at the slip plane between the tube and tire and the tube hysteresis? So maybe a tube with a bit higher hysteresis has a lower frictional loss? Has anyone tried the difference between a dry tube in tire and the same tube with baby powder? Is there a difference?

what i'm not quite understanding is how that paradigm works for latex and not for plastic. unless what's being claimed is that plastic is just less elastic, so is not the damper that latex is.

Elasticity is how stiff the material is. Hysteresis is a separate property. Steel is very stiff, but has very low losses to hysteresis, so it makes for good springs: very little energy is lost to heat when you spring a steel spring.

Keep in mind that, with bicycle tires, the astronomical majority of stiffness is provided by air pressure. Not the material of the tires (and tube).

What's being claimed is that plastic tubes are more of a damper than latex.

i'm hanging onto the concept here. it's the energy lost, measured in heat, that occurs during the process of deformation and return to original shape. what i'm not quite understanding is how that paradigm works for latex and not for plastic. unless what's being claimed is that plastic is just less elastic, so is not the damper that latex is. but if that were the case i would think that would be found out in drum test that use a proud feature on the surface of the drum (diamondplate).

*Regarding this property, bulk metallic glasses can behave as an even better spring with improved energy return.

New Cervelos are ~10W faster than a P5-6 at 45km/hr?

As a material scientist, this use of terminology is making my head hurt and conflating your misunderstanding. Some quick definitions. If a material behaves elastically, after it has been stretched (or compressed) by some load, it recovers its original shape after that load has been removed. If it behaves plastically, after the load is removed it keeps some permanent deformation – i.e. it has been plastically deformed. Most materials combine elastic and plastic properties, depending on the amount of stress or deformation applied. Small deformation: elastic zone. Larger deformation: can enter the plastic zone. An easy example is to think of bending a steel rod. Bend it a little and you remain in the metal's elastic zone, and it "springs back" into its original shape after you stop applying force. Bend it too much and, even though it springs back a little, it will also be permanently bent from the plastic flow. Confusingly we also call a whole branch of polymeric materials "plastic" because they can be easily formed into different shapes plastically during their production, even though in use they may behave elastically or plastically, or most commonly some combination thereof.

When it comes to the rolling resistance from the different kinds of inner tubes, whether or not one material is more elastic than another is pretty much a moot point, since in standard conditions (i.e. not being impaled by a nail or something) they are in any case operating in their elastic zones. However, as they are being stretched and recovering their shape during each rotation of the wheel, there is an energy loss. This is from the hysteresis that has been discussed. This occurs because they are imperfect springs: the energy put into stretching is not returned when they recover their original form. Maybe an easier way to understand this is to consider them not as springs, but as a spring and damper system, with the damper accounting for the energy loss. Effectively a latex tube has a "smaller damper" than tubes made of other materials.

The reason behind this damping term will be related to how different rubbers and polymers (or "plastics") stretch. In an "ideal" spring such as steel, the stretching derives from stretching of atomic bonds, which gives a great energy return.* In rubbers and polymers, the stretching can instead be due to stretching, bending, twisting and sliding of long molecular chains. If, for instance, sliding is involved, that will create the "internal friction" that has been mentioned, and hence a larger damping term and greater energy loss from hysteresis.

*Regarding this property, bulk metallic glasses can behave as an even better spring with improved energy return.

As a material scientist, this use of terminology is making my head hurt and conflating your misunderstanding. Some quick definitions. If a material behaves elastically, after it has been stretched (or compressed) by some load, it recovers its original shape after that load has been removed. If it behaves plastically, after the load is removed it keeps some permanent deformation – i.e. it has been plastically deformed. Most materials combine elastic and plastic properties, depending on the amount of stress or deformation applied. Small deformation: elastic zone. Larger deformation: can enter the plastic zone. An easy example is to think of bending a steel rod. Bend it a little and you remain in the metal's elastic zone, and it "springs back" into its original shape after you stop applying force. Bend it too much and, even though it springs back a little, it will also be permanently bent from the plastic flow. Confusingly we also call a whole branch of polymeric materials "plastic" because they can be easily formed into different shapes plastically during their production, even though in use they may behave elastically or plastically, or most commonly some combination thereof.

When it comes to the rolling resistance from the different kinds of inner tubes, whether or not one material is more elastic than another is pretty much a moot point, since in standard conditions (i.e. not being impaled by a nail or something) they are in any case operating in their elastic zones. However, as they are being stretched and recovering their shape during each rotation of the wheel, there is an energy loss. This is from the hysteresis that has been discussed. This occurs because they are imperfect springs: the energy put into stretching is not returned when they recover their original form. Maybe an easier way to understand this is to consider them not as springs, but as a spring and damper system, with the damper accounting for the energy loss. Effectively a latex tube has a "smaller damper" than tubes made of other materials.

The reason behind this damping term will be related to how different rubbers and polymers (or "plastics") stretch. In an "ideal" spring such as steel, the stretching derives from stretching of atomic bonds, which gives a great energy return.* In rubbers and polymers, the stretching can instead be due to stretching, bending, twisting and sliding of long molecular chains. If, for instance, sliding is involved, that will create the "internal friction" that has been mentioned, and hence a larger damping term and greater energy loss from hysteresis.

*Regarding this property, bulk metallic glasses can behave as an even better spring with improved energy return.

if the plastic innertube acts as a damper, measurably beyond what you'd find in a latex tube, why is it as fast? or faster actually than most latex tubes?

I think the misunderstanding is that you're assuming that latex tubes are slower than plastic. Most of the test data I've seen, including what was posted earlier in this thread, suggests the opposite.

...then why - even on drums with proud features, especially on those drums - don't plastic tubes test measurably more poorly?

As noted above, the data shows that MOST latex tubes have less material damping (hysteresis...not an analogy, but the same thing) than the plastic tubes. If they're close, that means the material damping is close. It's that simple.

As far as results on drums with "proud surfaces" goes...all it will do is change the relative reading, but not the percent differences. The "proud surface" basically acts as an "amplifier", so that small differences can be more easily teased out...but the same can be accomplished with a smooth roller of a smaller diameter to increase the deflection at the contact patch for a given wheel load. Which is why I don't see the point of the "diamondplate" type rollers.

are you saying then that the plastic tubes have about equal damping properties to the michelin latex tubes? and should therefore exhibit a ride feel about equal to them?

the thing about the plastic tube is that it's got the speed of latex but (claimed) better flat protection and no leak-down.

That said, I have no experience with them.

If the tubes have similar damping, then the "ride feel" is going to be more a function of the tire construction and pressures selected.

would you like to have some experience with them?

Most likely...they aren't going to add much to the spring rate of the tire and air pressure...so yeah, I wouldn't expect them to be noticeably different. That said, I have no experience with them.

If the tubes have similar damping, then the "ride feel" is going to be more a function of the tire construction and pressures selected.

Sure...but if I flat with them, you'll hear me cursing all the way down there in Valyermo ;-)

i have 3 of these, in the boxes, and i'm never going to use them because, of course, why would i! i'll send them off to you, and you can tell us all how you found riding with them, versus latex. put them thru whatever paces you want. put them on your text rig or put them on your bike and ride around. see if you can set a FKT down gibraltar ;-)

i guess material thickness plays a part , and thinner material almost outbalances thicker latex, would that be right?

Which ones do you have, Schwalbe? What size?

I'm never going to set an FKT down Gib...too dangerous without it being closed, and my self-preservation genes are more highly expressed as I get older :-)

i was joking on the FKT. bad tire joke. i have the schwable aerothans. actually i have 2 pair. 1 is all-round, that is to say, gravel. 35mm to 50mm. the other pair is "race" and by that it means "road": 23mm and 25mm and i believe up to 28mm. they're both 700c, 40mm presta valves. the road set are 41g each, the gravel set are 61g each.

Yeah...I'll play around with them.

either? both?