Which material damps vibration best - steel or aluminium?

[mangocrazy]

Following on from my 'ramblings' post, I was wondering what difference a choice of material (i.e. steel instead of aluminium) would make to the vibration absorption (or rejection) properties of handlebars made of differing materials. Would there be any noticeable difference between a set of steel bars compared to a set of ali bars?

How does this work in the cycle world where you have frames made of steel, aluminium and carbon fibre? Are their obvious points of difference in the way the bike rides depending on the material? I'm chiefly interested in how the different materials handle and transmit (or not) vibration. I remember the late and greatly missed Derek Chittenden telling me that riders on his CF framed Sounds of the Singles bikes noticed that the CF frame damped vibration compared to the box section steel frames they ran previously (Derek missed out aluminium completely and jumped straight from steel to CF).

So, whaddya fink?

[Yorick]

I have bar ends with lead in. Work great

[mangocrazy]

I have bar ends with lead in. Work great

Did you buy them or have them made? I'm sure lead would do a great job at damping the vibes, being both heavy and soft.

[Yorick]

I have bar ends with lead in. Work great

Did you buy them or have them made? I'm sure lead would do a great job at damping the vibes, being both heavy and soft.

Ebay specials

[Count Steer]

I'll be v interested in the answers to this. In theory denser material works better but shape and frequency is a big factor (tuning forks are dense material but resonate very, very well - steel ones probably better than aluminium ).

I expect it needs an 'Oi! Dazzle'.

[MyLittleStudPony]

Wouldn't it be steel because it's more dense and less stiff?

[mangocrazy]

And just to add more confusion into the mix, there are a bewildering variety of grades and alloys of both steel and aluminium...

[Count Steer]

And just to add more confusion into the mix, there are a bewildering variety of grades and alloys of both steel and aluminium...

Yebbut it's the resonant frequencies of the sticky out bits that counts - à la tuning forks - which is why the bar end weights work. Material stiffness will affect the frequencies but essentially you have to tune them so the resonance is where you want it ie outside the usual rev range. (I think).

[Mr. Dazzle]

Mate, seriously, this is a technical specialism all in itself! The guy who sits next to me is quite literally "Lead Technical Specialist - NVH". NVH (Noise, Vibration, Harshness) being industry speak for everything the hums, buzzes, squeeks, rattles, jiggles, whirrs, whines, groans and generally is noticeable.

In a nutshell though, yeah composites (like CF) are typically way more damped (not 'dampened' BTW, that's a top way to trigger an NVH person, unless you're talking about a water fight ). Generally any time you 'switch' materials or go across a joint or something you knock down vibes. Hence why CF is good. Polymers are typically way more damped than metals too.

Ally vs. Steel is gonna be basically the same when you're comparing steel vs. CF for example. Wood is way more damped than CF though, which is why CF piano boards are really good, but CF bells are shite, IYSWIM.

But a CF frame is going to have significantly different vibration properties because of all the other constraints you place on a CF frame, not from a deliberate vibration POV IYSWIM. Or an ally one, or a ti one etc.

Regarding handlebars it'll be as much about the frequency as anything, which gets even more complicated. Lead weights for example don't remove energy - they can't - they just change the frequency/amplitude of things so you perceive it differently. On the other hand, the OE https://en.wikipedia.org/wiki/Tuned_mass_damper on your Aprilia do remove energy in a round about kind of a way. Stictly speaking they don't, they sorta 'move' it, but it's more effective than just "dumb" mass.

Basically your question requires an awful lot of 'backstory', most of which is just O-level physics at the core, to answer!

[Mr. Dazzle]

I tried to find some quick numbers to demonstrate here...but honestly, it's gets pretty 'kin jargony pretty quickly!

Here's a really simple table, a big number is more damped, note how they lump "metal" into one category. They're also talking about "viscous damping" which strictly speaking isn't what's going on in your bars...but like i said, jargon.

https://help.solidworks.com/2016/englis ... ratios.htm

Lead is more damped than steel or ally but in the context of a bar weight that doesn't matter. The lead isn't getting squashed/stretched it's just a dumb chunk of mass flopping about not really damping anything. An equal lump of AN Other material of the same density would do the same job.

[ChrisW]

Generally any time you 'switch' materials or go across a joint or something you knock down vibes.

Is this why steel frames, Cro-Mo etc, being alloys are more complaint/less buzzy?

[Count Steer]

I tried to find some quick numbers to demonstrate here...but honestly, it's gets pretty 'kin jargony pretty quickly!

Here's a really simple table, a big number is more damped, note how they lump "metal" into one category. They're also talking about "viscous damping" which strictly speaking isn't what's going on in your bars...but like i said, jargon.

https://help.solidworks.com/2016/englis ... ratios.htm

Lead is more damped than steel or ally but in the context of a bar weight that doesn't matter. The lead isn't getting squashed/stretched it's just a dumb chunk of mass flopping about not really damping anything. An equal lump of AN Other material of the same density would do the same job.

As you say, it's not the damping property of lead that matters it's the mass. Stick a couple of lumps of lead on the ends of a tuning fork and the resonant frequency changes. Handlebars are a bit like the prongs of the tuning fork. If you could put the lead lumps inside the bar ends and screw them inwards and outwards you could tune the bars.

[porter_jamie]

To make the ally bar as strong as the steel one you have to put loads of material in which makes it really stiff. Ally also has a worse fatigue life so you need to stick more in for that. So steel although stiffer and stronger, can be less stiff as a component because it is stronger, and has a better fatigue live. The stiffer the bar the less damping it will have.
See pushbike frames, fancy 853 frames ride better than ally ones. The ally ones will be lighter than the steel ones strength for strength because even though there is more material, ally is much less dense.

[mangocrazy]

Yeah, I'm not underplaying the level of specialism here - just trying to figure out a general direction to follow. And the use of 'dampening' when 'damping' is being discussed really gets on my nerves as well. Normally it's Merkins that are guilty of that IME. The real point of interest for me is whether I should use aluminium or steel as a material for handlebars. My spider sense would say use aluminium as that has a greater mass compared to its weight, but I may be completely off beam in that respect (I'm sure you'll let me know if I am...)

Either way I'm going to reinstate the OE damping arrangement as soon as I can, whether it's in a steel bar or an ali one. And as Aprilia made the OE bars on the Falco out of aluminium, I'm guessing they had good reasons to do so, besides a spot of weight saving.

My mention of CF was probably a distraction, as there's no way I'm ever likely to be using CF as a handlebar material.

Thanks.

[porter_jamie]

The resonant frequency is a different thing but I'm answering the question posed. Tume.the Freq with a mass damper in this case a bar end

[Mr. Dazzle]

Honestly I'd use steel for a way more fundamental reason.

You can get away with a lot using steel Tough as old boots, doesn't mind being dinked a bit, much easier to weld....

I suspect Aprilia used ally for cost more than anything. Or cost/weight/stiffness optimisation.

This kind of "perceptual" vibration though, you've got no chance of doing it "on paper" first without an awful lot of prior expertise IMO. Suck it and see.

[Horse]

Concrete

That'll damp out anything, no probs

[mangocrazy]

The resonant frequency is a different thing but I'm answering the question posed. Tume.the Freq with a mass damper in this case a bar end

Yes, I'll be reinstating the OE Aprilia mass damper as soon as I can. But I'm curious as to what difference in vibration levels will be felt using a steel handlebar as opposed to an aluminium one. In the chart that Mr D linked to, it would appear that steel has inherently better damping characteristics than aluminium.

[JackyJoll]

Experiment with various weights on the end of the bars and also with one side heavier than the other.

[porter_jamie]

Steel generally has.berter elongation that ally too so if you fall of it will bend not snap