In forty years of cycling, I have often tried to use new equipment, always with a certain amount of patience and some expectation that I might find myself into some troubles. Well. I got a pair of Bontrager tubeless wheels with my new Trek Madone and I dared using them in the New York area, famous for roads in bad conditions and abundance of flats. I had a few simple punctures easily fixed on the road side and was congratulating myself on the selection of my tires. I loved the smooth feel of the lower pressure, and the nice cornering sensation while descending. The nightmare came when I had a nasty slash on a fairly brand new rear tire. Along with the typical noise of the air blowing out of the tire, there a geyser of the sealant *** as it was projected by the rolling wheel all over my bike, my clothing and even on the face of the guy riding behind me. That was not the end of it. Beside the fact that the tire could not be fixed on the spot, cleaning the bike turned out to be a nightmare as the sealant became dry, the silicone stuck on the paint of the frame, as well as coated the gears , the chain and even inside the brakes and the cranks around the BB. Not to mention the DI2 connections and the battery case. A horrible mess. Needless to say, I am back on my old clinchers with tubes inside and a few bucks short since I had to get rid of the chain and the cassette. Tubeless users, beware.