The task of fixing a squeaky bike can be made easier if you are able to determine the part that is squeaking. Look at the spots where two or more parts are attached to each other. If for some reason, you are unable to determine which part is squeaking, look for an area that may need repairs, and hone it. Check if the bike still squeaks; if it does, move on to the next step.
Loose nuts and bolts can often cause a bike to squeak. Use relevant wrench from a wrench set to properly tighten up all the nuts and bolts on your bike. Take a short ride to determine if the problem still persists.
Loose bike seats are another reason cause of squeaky bikes. Tighten up the bike if required. Moreover, check the spot where the handle bars of your bike are connected to the bike’s body. This connection often gets loose over a period of time and needs to be tightened. If none of these fixes work, move on to the next step.
Get rid of friction in chain and gears of your bike with a bike lubricant. Make sure that the lubricant you use is manufactured specifically for bikes. WD-40 is one of the best lubricants that can be used on a bike.
Bikes often squeak because if the break pads rub on the frame of the bike. A possible fix to this problem is to replace the old brake pads with new ones. If that is not possible for some reason, you should at least adjust the alignment of the break pads.
If none of the above techniques work, take your bike to a repair shop as a last resort. Of course it will cost a lot more to have the bike fixed at a repair shop than doing it yourself.