By Julien Pretot PARIS, Sept 18 (Reuters) - Long hailed as cycling's next big thing, even drawing comparisons with the great Eddy Merckx, Peter Sagan will silence his critics if he finally claims a top-notch victory at the road cycling world championships. The championships in Richmond, Virginia starting on Sunday have returned to the United States after a 29-year hiatus. Sagan has managed eight top 10s in the Monument Classics, but never won despite being the pre-race favourite several times. More...