I've seen some discussions (i.e. flame wars) concerning whether WD-40 is good for cleaning the bike's frame, as compare with OMS (Odorless Mineral Spirits).
Today I cleaned the right fork with OMS and the left with WD-40. After a 61-mile ride, the WD-40 side was covered with small black specs, and the OMS side was clean. I'll take pictures later.
I'll still use WD-40 to clean anything that could rust, but for the frame on my aluminum bike I'll use OMS in a spray bottle.