Remove all accessories (lights, bells, etc.) on top of the handlebar.
Turn the bike upside down so you can remove the wheels and inspect the drive train.
Carefully remove the front and rear wheels to give you more room to work on the bike.
Clean the chain of transmission (gears, chain, and crank) with a brush and soapy water. Also use a damp cloth with soap on the chain and rear derailleur. Try your best to clean all moving parts.
Once you clean your bicycle components sure to dry them thoroughly with a towel so they do not rust.
Wash the underside of the frame and front fork, cycling and ensure that all moving parts are free of debris.
Wash the front and rear wheels when cleaning the rim, the spokes and cassette. Then, put the wheels back on the bike.
After giving each rear wheel spin on the bike to ensure that the wheels are true and they do not rub on the brake components. If the wheels are not true and / or friction on the brake components make the necessary adjustments.
After your system is back in place, turn the pedals to check the chain of transmission. Make sure the bike pedals smooth. If you hear strange noises coming from your wheel bearings continue its investigation.
Turn your bike right over it and wash the top. Remember to dry the bike thoroughly.
Test your brakes front and rear and make necessary adjustments.
If the inspection apply your front and rear shocks. Make sure they are in good working condition.
Lubricate well you drive train (chain, sprocket, crank and derailleurs) with the recommended oil. Apply the oil while moving the pedals in both directions to ensure that components are properly lubricated.
Finally attach any accessory that you removed in step one.
The steps listed above will help you keep your bike in good condition and also help you prepare for your next race. If any mechanical malfunction is detected during the process make sure it is addressed. Your local bike shop, which sells mountain bikes for sale and bike parts, will be able to help replace a component if additional assistance is needed.