Proper bike jargon lesson: don't refer to gears by number. Say how many teeth. So you might say, "I started my climb in my 42 X 21, but by the time I reached the top I was down to my 30 X 23." The first number is the number of teeth on the front ring, called the "chainring," and the second number is the number of teeth on the rear ring, called a "cog." If you don't know how many teeth, get down on your sore knees and count them, noting the numbers on a piece of paper. Memorize them.

An old school thing was create a table showing the "gear-inches" for every gear combination, laminate it and afix it to one's stem. Then one could see what the gear combination for the next gear up or down would be. With the advent of 8, 9, and 10 speed cassettes, this is no longer important. One calculates gear-inches by dividing the number of teeth on a cog into the number of teeth on a chainring and multiplying by the nominal wheel diameter, 27" for a road bike, 26" for MTB.

It's a good idea to create a spreadsheet with this information and study it a bit. It will give you some insight into possible gear combinations and keep you off your bike for a bit. Normally one does not "cross-chain," meaning to run in the big ring and a big cog, or in the granny ring and a small cog. This is thought to increase chain and tooth wear.

And do concentrate! Keep those rpms up around 90 on the flat and 80 climbing. While you're doing that, concentrate on form. Back straight, elbows in, head up, shoulders dropped, knees directly over pedals, no upper body movement. Breathe conciously and deeply while climbing, all the way to the bottom by expanding your belly first, then your chest. Keep your throat and mouth open while breathing deeply.