If they're like other models (e.g. 350F), they're not threaded but sort of pushed on there tightly. Look around where the chrome piece meets the fork -- there should be a small screwdriver-head-sized slot. Guess what? Stick a screwdriver in it and twist a little. The chrome pieces are pretty fragile -- they're not going to break apart or anything, but they're pretty soft so twisting in the slot can give you tiny dings (and some for the fork lowers, the metal is a little soft). Go slow, be gentle, try wrapping the screwdriver head with something, and once you have a small crack rotate your leverage point around the fork, and alternate pulling from the top and trying to move it back and forward. If there isn't a little slot there -- nevermind!