Improving my bike maintenence knowledge is on my New Years resolution list. In the meantime I could use some help. I have a Cannondale 10 speed racer with 105 gearing. When I shift the gears on the rear cassette the shifter clicks for the first 4 gears but the chain does not move. On the 5th click it moves to the small cassette ring. The gears shift correctly for the next 5 gears and then will not shift anymore. The chain will not move onto the last 4 large cassette rings. Could someone offer some advice please?