Bicycle Mechanics - need help solving annoying clicking/shifting issues

Need help solving the annoying clicking on my Boulder SE. When I’m in any medium range gears (2-4thru 2-6, 3-4thru 3-6~ (see below)), there a clicking sound at every 90deg of crank revolution. Its hard to spot where its coming from, but it doesn’t sound like its coming from the back. When on lower range or higher range gears, it doesn’t click. Also, when in 2-6 (see below), not only does it click, but when my right foot pedals down, theres a series of clicks, maybe like the chain is rubbing? I tried tinkering with adjustment screws and such to no avail, but I’m also a newb when it comes to this particular stuff. I hate to take it to my LBS cause they are always so slammed and they would love to take the time to show me(they have been real helpful most the time, course I’ve also thrown a lot of money their way), but like I said, always slammed.

Also, I can’t get it to shift into 3-X unless I hold the thumb shifter down. I tinkered with the adjustment screws on the front derailer & cable adjusting nut with no luck. Any suggestions? Shifts fine into all the other gears. I’m guessing this has something to do with what’s happening above.

What is the proper why of saying what gear you are in? I just look at the shifters, on the left it has 1-3, right is 1-7, hence why I was saying 2-6, 3-4, etc.

i hv no idea how to fix, but wish someone can help u !

If the noise occurs when the crank is at a specific place, it's most likely to do with that. It sounds familiar to a problem I had. Turned out that my bottom bracket was ever so slightly loose and was rocking a bit in certain gears. Try tightening it up a bit and see if that helps at all.

If the noise occurs when the crank is at a specific place, it's most likely to do with that. It sounds familiar to a problem I had. Turned out that my bottom bracket was ever so slightly loose and was rocking a bit in certain gears. Try tightening it up a bit and see if that helps at all.

thanx. How should I go about doing this?

Make sure your pedal or crankarm isn't contacting the end of the cable on the front derailleur.

Oh yah, p.s.

Don't be messing with limit screws unless you know what you are doing - you're likely to throw the rear derailleur into the wheel, causing lots of damage and expense.