General Cycling Discussion - Vibration Damping -- steel, ti, cf, al, other?
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12-10-07, 03:42 PM
Carbon frames supposedly dampen vibrations very well. How do other materials compare?
And how important is this? Are there other ways of accomplishing the same thing? (Or is it in large part another case of being sold a load of hype from marketing, sales and advertising people?)
Some people claim that certain vibrational frequencies are fatiguing, especially on longer rides. This sounds reasonable or plausible in theory -- but how true is it in actual practice?
12-10-07, 04:07 PM
Get a hammer without padding on the handle (damaged etc) or a metal tool (crowbar) and hit another metal object with it. You feel that instant numbness in the palm of your hand?
Take a bike - it's more cushioned (tires are on the ground) but you can imagine if you hands went instantly numb and tingly as soon as you hit a bump. In fact, you can replicate this - ride a steel bar with no tape. Ride over 50 yards of heavily cracked pavement. Presto! Instant numb hands.
So yes, it's important to absorb or otherwise deflect some of that sharp shock. Aluminum and carbon fiber bars are a huge improvement over steel ones. Ditto forks, seat posts, even stems. As for frames and stuff, that's really debatable since it's impossible to be consistent design-wise from one material to another. However, personally, I think there is a big difference in damping properties of different materials, *as long as they are used correctly*.
The last bit is important. Used to be that aluminum frames (Vitus) were noodles, like limp spaghetti. Now people think of them as original generation Cannondales and say they're too stiff. It's not material, it's design.
12-10-07, 04:17 PM
(Or is it in large part another case of being sold a load of hype from marketing, sales and advertising people?)
The width and air pressure of the tires makes a much bigger difference than the frame material.
12-10-07, 04:42 PM
Let's not forget frame design. You can make a frame from damn near any material ride like a shopping cart or a noodle.
12-11-07, 11:45 AM
700x28 tires and a steel frame (2005 Gunnar Sport) beat the hell out of my previous aluminum bike (1999 Fuji Newest).
12-11-07, 01:18 PM
I'm with the previous post: You can design a frame to do anything you want, but if you're trying to change the ride of a bike you already have, the fastest, easiest, cheapest and most effective method by far is to use larger tires at lower pressure. I haven't bought tires narrower than 32mm in years, and usually ride 35s at 75-85 psi. The ride's great, and the effect on speed and rolling resistance has been hugely exaggerated. I've been riding the same 12-mile commute since 1979, on all kinds of bikes and equipment, and the tires just don't make much difference in speed or perceived fatigue.
AL provides the least amount of damping. Because AL doesn't take kindly to any deformation, AL frames have to be designed so they don't deform at all, which makes them very stiff. I would call them harsh.
Steel and Ti are both able to deform and then return to their original shape. The degree to which they do this depends upon the design of the frame, and the designer can play around with the shape and size of the tubing to tune it to optimize strength, rigidity, and damping - but it is limited based on the characteristics of the material.
CF provides a ton of flexibility in design. It's a very rigid material - like aluminum - but unlike aluminum there is a lot more tunability in terms of where it is rigid and where it is flexible.
I've ridden "performance" bikes with frames made out of all 4 materials, and was surprised how different they felt, even though they were all riding on carbon forks.
I really like the damping on my Madone.
12-14-07, 09:03 AM
i think its somewhat hype too. I have a felt f1 team frame, traditional geometry, carbon frame. very much harsher ride than my (relaxed frame) carbon specialized roubaix. and i think anyone would notice the overall stiffness of the felt compared to the roubaix. the felt is harsher, with more vibration then my e5 aluminum tricross. dont get me wrong, i like the felt, just use it where its at its best.
I don't like aluminum bikes after an hour or so. I prefer steel. Carbon is overkill for me, but others really like it.
12-20-07, 03:38 PM
Its true in practice, but like others have said, tires, grips and saddles play a large role in it.
I've never been on a CF bike, never been interested due to the big downsides you get along with the material, like dislike of having stuff clamped to it.
Titanium is a fairly nice ride, but i've only been on titanium a few times before. Its too hard to say how it stacks up to the others though, as the tires/grips/seat weren't constant.
The closest compare I can make is that we have several bikes around here, and the most comfortable ones are *easily* the steel ones. But thats not the only side of the story:
Steel #1 is a typical 1990's rigid MTB which has an Xtracycle on it, so along with having nice grips and such, wheelbase is extended, which also smooths out the ride quite a bit. This is easily the most comfortable one in the pack actually, with the big tires, long wheelbase, and good grip/saddle combination, there's almost zero vibration coming off the road, and it sucks up bumps. I'd rather tour on this than my touring bike.
Steel #2 is a classic 27" touring bike with gel/cork wrap on the bars and a properly fit seat. Very comfy.
Aluminum #1 is a "hybrid", and aside from Ergon grips, is uncomfortable. Vibrations on this bicycle are highly noticeable, but i'll be getting it some Big Apples someday.
Aluminum #2 is a full suspension all mountain Y-frame design. This bicycle is uncomfortable for extended periods of time.
Off my personal bias, aluminum is the only design that I find is not good in regards to vibrations. This may or may not be because of the material, but its because of the design: Aluminum bikes are made *not* to vibrate or flex, as that can ruin the material.
12-21-07, 01:00 PM
Steel will deal better with vibration "harmonics" better than any other
material right up the the point of failure.
1st order harmonics will just buzz your hands. Where 4th order
harmonics will make it painful to hold on. Vibration is one thing
but it's the harmonic amplitude that does the deed.
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