... "alu frames offer no comfort" to the list, a myth that frequently pops up...
They also say "lots of road buzz" and "harsh ride quality." This is something I never really understood.
... comfort is the combination of frame, wheels, spoke tension, tire pressure, saddle, even stiffness of the handlebar
Lets assume we have two identical bikes - components, wheels, etc., all the way up to the frame geometry. We will isolate just the frame for this argument - its material and the frame's design
. One is carbon fiber, the other aluminum.
Good carbon fiber has a higher elastic modulus than aluminum, and therefore will flex less, be less compliant, and therefore be stiffer. A stiffer frame would translate to a harsher ride.
Then why is carbon fiber "more pleasant to ride"?
Two reasons: 1) the way the carbon is laid up, and 2) the design (shape) of the frame. These two go hand-in-hand in manufacturing a CF frame. Compliance is built into
the frame via its design (curved seat/chain stays which "bend", various top/down tube shapes). However most of these forms do not hold stress well, and this is where the lay-up of the CF cloth is critical to give it structural rigidity. You get a strong stiff frame from the material; and a compliant one from the shape of the tubes and the design of the frame.
Early aluminum designs were done with straight tubing. These directed forces from the road along the lines of the tubing, resulting in a more "feel" for the road (i.e. road buzz). I think this is where aluminum got its bad reputation. An elegant solution was the "compact geometry" IMO. Yes it did make the frame a lot stiffer, but the extended seatpost allowed for more "flex" on the post, giving a reduced feeling of buzz on the saddle. Using a CF seatpost made it even better.
Today's hydroformed aluminum tubes allows manufacturers to the use tube shapes previously possible only in CF frames, giving aluminum frames similar ride characteristics to that of CF frames. Gone are the days of "harsh aluminum bikes."
I know there will be pundits and naysayers, and people with their own opinion against aluminum regardless of the facts that are presented. I can't win them all.