the past few rides my chain has been doing some bad things. i have a shimano 105 double with a 9 gear hub (did i say that right?). when im shifting from the low to high gear in the front the chain just pops right off towards the crank. then in the back, the 3 or 4 gears closer to the wheel are going CRAZY! when trying to downshift the chain cant make up its mind where to go. it hops from 1 gear to the other then back and forth. doesnt sit on one of the gears just keeps switching.
ummm, help me?