I got some back in 1999 and sort of liked them. No worries about a flat in goathead/puncture vine territory ever again. But they really slow you down. I used them for my commuting bikes with 26" tires, so speed wasn't as important as no flats. Later, I tried them on my EZ-1SC recumbent with 16" front and 20" rear tires and they were awful. I could barely pedal the rolling resistance was so high. Took them off and put on Maxxis Hookworms.