i have the cult dehart tyres too, great tyres but they are actually bigger than stated. i got the 20x2.1 and had a problem on front and back brakes, they measure 20.5x2.25 when inflated. i had to cut a slot on the back of my forks so the cable would miss the tyre and the rear tyre hit the brake on my s&m laf frame. i ended up changing the frame back to my mcneil loden frame and all fits fine.