Bicycle Mechanics - trek 7100

I have a question for all you mechanical gurus: I recently bought a trek 7100 hybrid. It skips between the biggest and second biggest cogs on the rear cassette, I have had it into the local lbs 3 times over teh last 6 weeks and it never quits for long. Could this be due to bad or inferior shifters, derailer. chain, or cassette, or all of the above? Like I said this bike is new and should be shifting smoothly. all other gears shift quite well with the exception of once in a while somewhere in the middle of the cassette it will skip. By skip I mean it shifts down to the smaller cog and once you put a lot of pressure on the pedals it will skip back to the larger cog. this is sometimes iratating others have almost caused me to spill.I like the bike a lot other than this ((well my wide but is not happy with the saddle yet)) I am willing to go to a different derailer as this has the sram esp 3.0. i guess the next question would be what would work with this cassette? or would it have to be changed as well?

Could this be due to bad or inferior shifters, derailer. chain, or cassette, or all of the above?

Yes, but most likely it's not a worn chain or worn cogs. Have you tried tweaking the barrel adjuster?

there is a barrel adjuster under the shifter and I have tried to adjust this I cannot get it to smooth out. at first i put it to new cables stretching, but after six weeks riding it everyday in town should all of the stretching be done?

If it's new,it's not likely the cogs or chain are worn.The deralier or hanger could be bent.More likely it's cable tension.I'd find another shop,or try www.parkltool.com for deralier adjustment.

ok I might try that but i have never been able to adjust a bike very well.

The Trek 7100 has a SRAM drivetrain with twist type shifters. Halfpipes (Longer version) if I am not mistaken. Be sure that when you are giving the bike your all that you aren't twisting the shifters as slight movements in them will occasionally move the cable causing misshifts or skipping around on the cogs. If you notice this to be the root of your problems there are shorter Grip Shifts available for about 30-35 dollars. Good Luck.

-Ryan

actually i noticed that i do twist a bit when i pull hard to take off and speed up maybe that is it