Originally Posted by joey buzzard

​​​​​HAvent tried these personally, but I thought that they looked like an intriguing option if I ever decided to build a Swift up with 451 tyres. One of my main beefs with the 451 standard (apart from tubes being rarer) is that most of the tyres manufactured for these wheels seem to be skinny profile road bike style things that once mounted make the difference in circumference between 406 and 451 much of a muchness but with inadequate material to deliver a comfortable ride. Hence I was excited by the 451 Powerblocks as these seemed a beefier tyre for 451. With the right v-brakes I figure these might just be doable with a Swift. Have you any experience with these yourself?