difficulty shifting to high gear on mtb
 

lately, i have been having a harder time shifting to the higher gears on my mtb. i have to hold the shifter for a little bit before it completely shifts, and if i do not, then it seems to be in a middle position and makes some noise. i am not sure what i should look for on the bike to solve this problem. what are some areas that i can check? or are the components i have just not that great?
i am riding a 2007 gary fisher wahoo. everything is stock.

release the cable from the clamp on the rear derailleur, then you can determine if the problem is in the dérailleur,
and not the in the cable run.

most likely just a little cable stretch.. put the shifter on the smallest chainring (slackest position) undo the cable clamp, pull the cable medium tight (doesnt have to be super super tight because it can break your shifter but pretty tight) and retighten the cable bolt clamp,, try shifting now

No need to release any cables. Your bike has tension adjusters built into the shifters. Shift to the smallest chainring and check to see if the cable is slack. Turn the adjuster to make the cable tighter (not super tight but taut). Go ride.

I am a newbie and my new 7.2 FX has this same problem but only with the front derailleur. How would I do this on the front? Thanks, Steve

Just to check, higher gears means smaller cogs?

If so, the next question is, was it a slow degrading over time, or something that came on fairly suddenly.

The following assumes that your, like most, your RD is pulled to lower gears (big sprockets) by the cable and returns to high by the spring when the cable is slack.

Here's what it isn't
cable stretch, since your cable seems to have magically gotten shorter.
a simple trim adjustment, since that doesn't change by itself to tighten the cable, so it pays to look for an underlying cause.

If it came on fairly suddenly, the most likely cause is the hanger having gotten bent in slightly. This is especially likely if all the gears seem to be harder to upshift one step at a time, and upshifting is quicker than it used to be, maybe even skipping a sprocket, or if even after adjusting the cable the RD has trouble shifting to the highest gear.

If the problem developed gradually over time, it's probably related to increased friction in the housing, either from wear or from muddy water wicking in and fouling them, especially the chainstay/RD loop. A quick test for this is to upshift one gear then pluck the bare wire away from the frame like a guitar string. If that corrects the trim, you have worn or dirty housings.

You might be able to correct the problem temporarily by using the trim adjuster, but that's only masking it, not solving it - the bicycle equivalent of putting a bucket under a leak to catch the water, rather than fixing it.

BTW- if it is a bent hanger, that means that your limits are now also mis-adjusted, greatly increasing the chance of putting the RD into your spokes, so check both inner limits as soon as possible.