Bicycle Mechanics - help derailler problem

i'm having problem adjusting the 7 speed derailler. When I shift from 7th geer to 6th geer, it would jump to 5th geer and drop back down to 6th geer. It does this on some other geer too. Does anyone have any suggestion of what I should do? Thanks

I would say a friction shifter would automatically solve all your problems...sounds like your having index problems I've seen it lots,I know for indexing to work perfect everything has to be perfect the shifter,the rear derailluer,the tension on your cable...But I have often found a simple inexpensive friction shifter will automatically adjust kor error:)

Your problem could be caused by sloppy shifter, misadjusted cable tension, bad cable or housing, poor frame geometry, misalligned hanger or the derailleur itself. Assuming that your shifter and derailleur are in good shape, first adjust the cable tension, with the adjuster at the derailleur itself. Then check your cable and housing, and replace them if they are old or bad. Then make sure that your derailleur hanger is straight.

Cable tension is to loose, turn the adjuster on the der. counterclockwise a quarter turn and try the shifting. If it still drops down, give it another quarter turn.

Rev. Chuck has it right. Cable tension is too loose.

Chuck