Can i change the gearing on my bicycle

I notice that the front gears are kinda screwey. I have a 15 speed, 3 gears on the pedal and 5 gears on the back wheel. On the thumb level gear shifter if you push it all the way to high it still doesn’t upshift into the 3rd gear on the (i dont konw bicycle jargon), so i figure that i would need to adjust the gear transfer thingie to make it stick out a little bit, so it can carry the chain up to the 3rd gear. How do i do this? Is there just a screw i adjust?

Yes there is. I used to repair bikes, but it was so long ago that I don’t remember what the adjustment is, but, be encouraged, it is there and I’m sure there is a Doper who will help you.

Get a friend to hold the bikes back wheel off the ground. Turn the pedal crank and observe the action of the front derailleur as it moves from one sprocket to another. As Faldage noted, there are stop screws which limit travel in both directions for the front chain guide-I’m suggesting this method so you can see what the mechanism is trying to do. You then know what screw to screw with. :smiley:

There is a screw adjustment as other posters indicated, but that might not be enough. Your cable might also have stretched over time and you may need to either replace it (not as hard to do as it sounds) or just tighten it up a bit. With only a five gear sprocket on the back, sounds like your bike is rather old. You may have a “barrel adjust” screw on either the deralieur end or the shifter end of the cable. If not, the cable probably runs thru a screw at the deralieur end which holds it in place. Loosen that screw and pull the cable thru a bit, then retighten. You might have to fool around a bit to get it right.

There are lots of good bike repair books out there. It’ll be a lot easier to do this kind of stuff if you have one on hand that has good pictures (which, as the saying goes, are worth a thousand words).

Sheldon Brown shows How-to, with pictures.