Originally Posted by Al1943

Many MAVIC hubs require a 2 mm spacer in addition to the 1 mm Shimano spacer at the back of the cassette when installing a Shimano 10-speed cassettes. This is because a MAVIC cassette is 2 mm wider than a Shimano cassette and a 10-speed Shimano cassette is narrower than 8 or 9-speed Shimano cassettes.