With several hundred miles on the Cerf blue's, 700 x 26, and having ridden the Cerf green's, the 700 x 28's for at least that distance, here are my impressions of these lovely riding tire(s).
They may puncture more often. I managed a pinhole leak on both sets of tires in the first few days of riding, and on the front tire with both, and never found the culprit. That said, I'm not sure that means much in the long run as these tires are so sticky when new. Sealed in plastic, they're not aged at all like many seem to say a good tubular should be. And the tread appears to be very similar to a good tubie. If you're the type who dusts tires after going through intersections and over stuff, these tires will practically burn you from friction when new. It becomes less so after a few weeks, but still a very sticky tread compound.
I think most experienced (anal like me) riders have a tire feel that they like. Some ride those really stinking narrow 20-22 mm tires (This is a biased tire survey after all. Just read between the lines). For me those tires have to be pumped up too hard to survive pinch flats and also ride with my comfort level ... and they just don't seem to have enough rubber on the road flying through hairpins.
And the 25's I've ridden and waxed ecstatic about for years that for the most part have really measured in the 25-26 mm width and were often called 28's, have been MY favorite on my favorite bike, a 30 year old fast road tourer. My old favorite tire, the Avocet Fasgrips rode well, and with Kevlar beads were quite light, with the exception of the 32's (measuring 28), and only available in a wire bead. I've owned & ridden those 28 mm tires, Roly Poly's, Ruffy Tuffy's, and 32 mm Pasella's (more for rougher touring and rail trail), and found them to be very nice, sturdy tires, and fairly light for what they are, but not what I'd call a road clincher for a thoroughbred road racing or fast touring bicycle.
So to me, 28 mm tires usually feel heavy, though the connection to the road seems enhanced. When riding the Cerf green's (28-29 mm) I found that they weren't noticeably a heavier tire, and were absolutely connected to the road. These tires ride absolutely lovely and may be the lightest 28's I've ever ridden. I found myself regularly letting air out of the tire periodically through a ride to get just the right comfort level, and that I could let a lot of air out if I wished, instead of the 90's, actually getting into the lower 80's psi range for my 200+ lb. weight, always with about 3-5 psi more in the rear. But ...
I got into a balancing act of letting air out to the point of the tire squishing against the road without quite getting the bump force I like. Almost the opposite of what I'd expect, having the bump force and road feel through the turns right for me, there was enough air reserve in the tire to make the overall ride just a bit harsher than I'd prefer. (Let Charlie Young tell you about the princess, the pea and me.) By getting the tire soft enough for the overall ride, bump force was way down, but the bike felt less secure or firm in hairpins. The tire was squishing to the point where it appeared to be on the verge of slowing the bike down (probably just my perception). The tire size and pressure were working against my riding style of hammering out the twisting downhills. Although I really liked the ride of the green's, I wanted to try the blue's since that was more my ideal tire size.
The blue Cerf tires rode as nice as I'd hoped, and felt lighter. They have my favorite balance of bump force and ride. I was still used to the road connection of the wider green's, and there was a bit less with the blue's, but that was soon forgotten after a couple rides. I still ended up letting air out so that my ideal balance now works out to around 96 x 102 psi fr/rr with my rims. I'd measured their width at about 25 mm when I returned from my first ride, and within a day or so, they measured almost exactly 26 mm. wide. The pressure balance for the Cerf green's seemed much wider, easy to put air in one day and ride for two or three, though I've always been a pump before the ride kind of guy.
Both sets of tires have a great ride for what they are. The green's may be the perfect tire for some. Also being the most expensive tires I've ever bought at around $120/pr. including shipping (twice the cost of my old Avocet's), it's a choice to make. Frame and wheels are what determines the bike's ride. I think tires make as much difference as spokes, spoking, rim section and flange width, and I've always liked the lightest, most supple tires I could find. I've normally dusted tires with fingertips as necessary and usually get to wear them down to almost the cords before starting to get flats. With these, I'm willing to deal with a few flats. Tubes and patches are cheap, but these tires really bring out the best in your favorite bike. Mine deserves nothing less. They may not ride like a good tubular, but are about as good as it gets with a clincher, and a much better size than those Veloflex's, as nice as they are.
Then again, maybe any 25-26 mm gumwall tire will do! Happy trails,
Dan Artley in Parkton, Maryland USA