This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.
From: Jobst Brandt <email@example.com>
> I'm getting a custom frame built and wondered what
> people thought of using 26 inch road wheels. Smaller
> wheels ought to be lighter and stronger.
and goes on to list advantages and disadvantages, most of which are less
that important in deciding what size to use. What in fact brought us
the wheel size (700 or 27") that we have is better understood by the
women riders who have a hard time fitting these wheels into their small
bicycle frames. Wheels would be larger than they are if they would fit
the average riders bike, but they don't. So the compromise size is what
we are riding today.
> It seems to me that the most obvious reason for using 27"
> wheels is tradition, but I'm not sure the advantages make
> it worth trying to swim upstream. What do you think?
This line of thought is consistent with the "cost be damned" approach
in bicycling today. The big bucks are spent by people who want the best
or even better than their peers. The more special the better. Riders
consistently spend nearly twice the money for wheels and get worse rims
when they choose anodized ones, whether there is merit to this finish
is of no interest. They cost more so they must be better. How "custom"
can you get than to have wheels no one else on the block has (maybe 25"?).
If enough riders ask for 24", 25" and 26" wheels, manufacturers will up
the price as their product lines multiply and the total sales remain
constant. Tires and spokes will follow as a whole range of sizes that
were not previously stocked become part of the inventory. Meanwhile,
bike frames will come in different configurations to take advantage of
the special wheel sizes. SIzes whose advantages are imperceptibly small
but are touted by riders who talk of seconds saved in their last club TT
or while riding to work.
A larger wheel rides better on average roads and always corners better
because it brings a longer contact patch to the road. A longer contact
averages traction over more pavement and avoids slip outs for lack of
local traction. Visualize crossing a one inch wide glossy paint stripe
with a 27" wheel and an 18" wheel when banked over in a wet turn.
I see this subject arise now and then and it reminds me of the concept of
splitting wreck.bike into several newsgroups. The perpetrators bring the
matter up for many of the wrong reasons.
Ride bike, don't re-invent what has been discarded.