Duane Hébert wrote:

I'm looking to replace my old road bike with a carbon fiber model.
My criteria a women's specific design, comfy for all day
riding, smooth riding, light weight, Shimano 105 components, and
preferably with three chainwheels.

Via the web, I've checked out the specs and reviews for following
bikes: Cannondale (Synapse Fem 5), Felt (ZW5), Giant (Avail
Advanced 2), Trek (Madrone 3.1WSD), or Specialized (Ruby Elite
Apex). I was hoping y'all might have some insights into these
bikes so that I could minimize driving all over the state (there
are no local dealers for most of these) to do the final fit
check-out and test ride. I don't know how comfort is specified on
a web page.

So here goes. Assuming equally good fit and tire size/psi - Do
any of these bikes stand out as more smooth riding? Do any of
these bikes stand out as more comfy for all day long cruising?
Does anyone have any idea how the weights compare for the same
size bike? Thanks for any help trying to trim down my list of
potential bikes.

NO! The comfort of a bicycle resides in its wheelbase and tires;
frames and wheels having practically no perceptible elasticity.
Therefore, test ride the bike and see if it fits your body: bars,
pedals, and saddle. You can't ask for more. If you chose a
suspension bicycle, you'll get speed instabilities that you won't
like. Get large enough tires 28-30mm cross section and brakes that
you like. That's where it's at!

Are you saying that all other things being equal, a bike with a CF
frame is not more comfortable than an aluminum frame? That a steel
frame is not more comfortable than an aluminum frame? Or am I
misunderstanding you?

I think what I wrote is unambiguous enough to not be misinterpreted.
You might review the FAQ on what holds the rim off the ground:

Subject: 8b.25 What holds the rim off the ground?

# What forces keep the rim of a wheel with pneumatic tires off the
# ground. It obviously can't be inflation pressure because it's
# uniform around the wheel.

# As has been mentioned, casing walls pull on the rim (or its
# equivalent) and thereby support the load. The tire casing leaves
# the rim at about a 45 degree angle, and being essentially a circular
# cross section, it is in contact with the rim over its inner quarter
# circle. At least this is a representative model. The visualization
# may be simpler if a tubular tire is considered. It makes no
# difference whether the tire is held on by glue or is attached to the
# rim as a clincher is. Either way the tire is attached to the rim, a
# relatively rigid structure.

So it is the angle of sidewall departure from the rim that gives
inflation pressure its load carrying abilities.
--
Jobst Brandt