Have they? Do you have support for that statement?
Why is it so implausible that different materials might feel different? I did a (non-blind) comparison of steel versus carbon fiber, and they felt very different to me. They also certainly sound wildly different if you just tap your finger on steel frame versus a carbon fiber frame, so a different "feel" that corresponds to higher frequency vibrations seems plausible.
Meaning, you switched out the frame on a bike from steel to carbon, keeping everything else, and felt a difference?
Here’s a video from Cycling About that gives a good overview:
I mean what frequency would you class as road buzz? With that we could start to analyse what's going on.
When I look at the damping ratio of steel[1] I see something around 0.01 - 0.05 which is under-damped.
Carbon fibre can be somewhat better at between around 0.1-0.3 i.e. an order of magnitude better but still not what I'd consider a shock absorber.
I'd be surprised if much high frequency vibration that's made it through the tyres is actually damped by the frame.
With regard to non-blind, anecdotal comparisons I own and regularly ride bikes made from steel, aluminium and carbon fibre. I'm in the camp that thinks a long flexible seat post will do much more for comfort than frame material.
If you know of a study showing otherwise though, I'd be really interested to see it.
1. Sorry I can't find exact figures for 4140 CroMo but I don't think it's outside of this range.
At the time, I assumed the difference was the frame material, but I really do not know the cause. I do believe there is something that could be quantified as opposed to just a psychological effect, but it could be something non-obvious like the typical curved shape of old steel forks; or the frame geometry or tube diameters; or even something else that just correlates with frame material like the tendency of old steel frames to have hand-built wheels with lots of spokes as opposed to the newer (seemingly) rigid factory wheels with fewer spokes.
I would expect that a person conscientious enough to know how shocks, wheel size, tyre type and pressure, saddle type, and speed affect ride comfort would also include that information in their post.
Therefore, these anecdotes amount to "I rode on two different bikes which happened to have different frame materials and I could tell a difference in the amount of vibration." Meaningless, even if we don't consider human biases, after all these aren't blind tests.
I would be curious to know if there is a difference that can be felt, but in the end it's of no practical use. I bet even slightly adjusting your tyre pressure will have 10x the impact of any possible difference in frame material.
I could have left out my anecdote because it is subjective and prone to bias and error, but it is how I believe I can rule out (some of) the commonly cited reasons of different bike feel -- seat posts, because that would not affect vibrations coming through the feet; and tire pressure, because different tire types and pressure have their own different and recognizable feel (e.g. responsive and jittery with high pressure, squishy and sluggish but not silky smooth with low pressure).
this isn't really true.
yes, exposed steel will show rust, but that's not what "corrodes" iron to the point of weakness. to corrode in a way that weakens iron, it needs to be kept wet over an extended period of time. If you've seen an old car with holes rusted through, that has occurred "from the inside" in places where water can collect and sit. The outside of objects will dry after rain, and such corrosion will never be a problem beyond aesthetics.
It's neither more durable or lighter than frames made of aluminium, titanium or carbon fibre.
For example, a typical frame made of steel will generally be about 1kg heavier than one made of carbon. The forks will 500g heavier. If you scratch or chip the paint steel will corrode.
The claims that steel (or titanium) "feels" better than aluminium or carbon fibre have been thoroughly debunked.
The Young's Modulus of steel tubes used in bike frames ends up almost exactly the same as aluminium or titanium and steel has no "magic" vibration absorbing qualities.
Carbon fibre is the only frame material with any real vibration damping and even that is massively over-hyped compared to an actual shock absorber or even bigger tyres.
If you want to choose a steel frame then it should be because you like the look, it's easy to weld, uses less energy to make or it's cheaper.