FRAME MATERIAL 
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The choices in frame materials are: steel, aluminum, titanium and 
carbon. 

Ti and Carbon are the most expensive and there is great debate about 
the virtues of different frame materials. The questions here are: 
weight, stiffness (responsiveness) and the mystical or mythical 
ability for a frame to absorb vibration or road shock.

I would gladly pay more for a steel or AL frame that met my other 
design needs than a carbon frame that didn't meet them. For me, these 
other design needs far, far, far outweigh the question of carbon fiber 
and road shock.

Now, I can't go so far as to say that carbon definitely does nothing 
for road shock. I can't back that statement up. But, in terms of frame 
material, what I can say is this:

a) I can't tell the difference in road shock between other frame 
materials that are supposed to be wildly different in terms of road 
shock. My AL frame is *supposed* to be harsh compared the long list of
steel bikes that I've owned. With similar bar set ups, saddles and 
tires, I honestly can't tell the difference. Again, not saying others 
won't or can't. Just that I can't.

b) I CAN tell a very big difference with different bar pads, saddles 
and tires. Anybody remember the good ol days with Bennotto tape over 
unpadded barzzzzzzzz! IMO, worrying about frame material with respect 
to road shock is like cutting the handle off of a tooth brush to save 
pack weight while carrying a 7 lb tent or like worrying about a skis 
ability to hold an edge on ice while skiing in low cut leather boots. 
If you want comfort, ride 25c tires at 90 psi, put gel under your bar 
tape and consider a Brooks saddle.

c) In terms of first principles, everything I've read points to utter 
confusion on the question of whether or not carbon should reduce road 
shock. One common argument seen on rec.bicycles.tech is that any 
vibration range that carbon tubes do dampen out are outside of the 
range of human perceptibility -- sort of a silent dog whistle argument. 
If anybody can point me to good study linking road shock reduction and 
carbon fiber in frames, I would love to see it.

d) In terms of history, there is good reason to be suspect about our 
own perceptions. In an infamous review way back (Bicycling, I think) 
they performed a true blind comparison between bikes. I think they 
painted all the (steel) frames. Editors who waxed poetic on the harsh 
or comfy rides of various frames beforehand were unable to find 
differences in the blind test or worse, picked "harsh" frames and 
comfy and vice versa. Again, I'm not saying that folks can't tell the 
difference by adding carbon frame or forks. Just pointing out that 
this typically doesn't happen blindly. And if history is our guide 
when things are truly judged blind, the perceived differences might 
have everything to do with our expectations and nothing to do with 
the materials.