There actually are wonderful tires in the 25mm width - try the Vittoria opens or perhaps the Deda Giro De Italia (made by Challenge) that may be available as a Challange model and meassures around 24mm.
But - a top quality 28mm (or 30mm) can be just about as fast as a narrower tire, but is lots more comfortable. The reason the Grand Bois tire is so exciting is that it isn't 25mm. In Bicycle Quarterly, it was shown, if my memory is right, that the Clement 28mm Del Mondos were FASTER with respect to rolling resistance than the Crit Setas. So the reason the Grand Bois is so great is because the size makes so much sense. The Thai Clement Paris Robaix tires in 24mm were actually slower than the 28mm Del Mondo counterparts! The reason is that the Paris Robaix had a heavier casing than the Crits - but only when a sufficiently wide casing is used, does the rolling resistance benefit of the wider tire outweigh the detrimental effect of the heavier casing.
Mike Kone in Boulder CO
> I've been riding the newer 700 x 28 Grand Bois 'Cerf' tires for a week or
\r?\n> so now, and really am pleased with how nice a tire it is. It's still a
\r?\n> bit larger than my ideal, but for it's size it feels lighter, rolls really
\r?\n> well and really sticks to the road. I believe Jan Heine compared the ride
\r?\n> to a Clement 'Campione del Mondo', I'm thinking more 'Paris Roubaix', but
\r?\n> that was a long time ago for me. The tread is razor straight while at
\r?\n> speed, really a nicely put together tire. Running 92 x 95 lb's. in the
\r?\n> fr./rr., they just about took out all the expansion cracks on my stiff RS
\r?\n> touring bike and my hefty heifer body, with just a couple more pounds for
\r?\n> my ideal feel. I've been looking for a nice gum walled daily rider now
\r?\n> for some time. This is as close a new one as I've found.
\r?\n> Now if I can only convince Jan to try to get the Grand Bois' in a 25-25.5
\r?\n> mm tire for that 'criterium seta' ride!
\r?\n> Happy trails,
\r?\n> Dan Artley in Parkton, MD