Bicycle Mechanics - Shimano gears initial set-up

I've just bought my first bike (not including the one I had as a kid!) and can't seem to work the Shimano gears properly.

The instructions tell me how to adjust the front and rear derailleurs when in highest/lowest gears for both, but when I try and shift to something in the middle like third, the chain starts catching on another part of the mechanism like the jockey wheel cage plate and sometimes it won't shift gear at all.

It seems however I adjust it there's always some part of the mechanism that isn't happy!

Is there anything I can do to set up the gears correctly or should I take it back to the shop?

Take it back to the shop, since you just bought it they will tune it up for free.....atleast they should.

I agree take it to the shop, if you have a really nice mechanic he might let you see what he does when he services it. :)

I concur with the others about taking a new bike back to the shop for adjustment. But for your personal understanding of the problem, it is the cable tension that needs adjusting, and that is done by the knurled nut on the RD where the cable enters the derailleur. Turning it counter clockwise increases tension and clockwise decreases it. If you move the shifter aand it doesn't climb to the next gear but starts making a clattering noise --increase the tension until the chain moves up onto the next gear. You may have to repeat this process a couple times until it works for all of the gears. You may even have to loosen the nut that holds the cable and pull it tighter. But the fix for the problem you are having is in the cable tension.

Once you have set the High and Low limits, there is no other use for those screws. Leave them alone.

Now that you understand what's going on, take it back to the shop so you can get the service you paid for when you bought the bike. Good Luck.

THANKS EVERYONE!!!!!!!!!!!!!!! :D