Would have been helpful to say how you've tried to get it off thus far. Dustcaps on most Shimano hubs (including RSX) are press-fit into the hub shell. If they're gonna come out, there are special tools to pull evenly on them, but I usually just use a flathead screwdriver to pry one side out first.
Sometimes dustcaps don't want to be removed, and removing them can crack or bend them. If you're having trouble with this, clean the old grease out as best you can and repack without removing the dustcap.
If you end up bending or breaking the dustcap in the process of getting it off, most bike shops have replacements in their small parts bins.
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"c" is not a unit that measures tire width
Last edited by TallRider; 10-13-06 at 12:58 PM.