Bike maintenance
Don't procrastinate when it comes to bike maintenance. If you notice a problem, remedy it immediately after the ride. Otherwise, it may slip your mind until you ride again.
The two easiest ways to ensure that your bike works well are to keep the tires inflated (to the recommended pressure listed on their sidewall), and to keep the chain well lubricated.
Silence annoying clicks and creaks in clip-less pedals by applying silicone spray to the shoes cleat where it contacts the sole, and to the pedals cleat-gripping hardware. Wipe off any excess. Grit won t stick to silicone the way it will to an oily lube.
Keep handlebar ends plugged so they won't take a core sample from your body in a crash. You will not be allowed to start a triathlon or cycling race without bar end plugs.
To keep out water and grit, place a small section of an old inner tube around a headset s lower bearing race the next time the headset is overhauled.
Hose down your bike while it s still wet from a rainy ride, then dry it with a towel. Lube the chain and the pivot points of the derailleurs and brakes. Spray a water-dispersing product, such as WD-40, into places where cables enter or exit housings.

Handlebars
When wrapping handlebars with handlebar tape start by strapping from the end of each bar and working towards the stem. Then with your hands push on the overlaps, not against them, to stop the tape from separating. Secure the ends near the stem with black or coloured plastic tape.

Seat height
Memorize the distance from the centre of the crank axle to the top of the saddle, measured in line with the seat post. This is good to know in case you ever need to ride a different bike for any reason. This measurement is commonly referred to as your "seat height".
Wrap a strip of tape around your bike's seat post where it enters the frame. Then you can tell if the post slips, and you can easily reset your saddle height if the post is removed.

Tires
Check tire inflation weekly if you re a recreational rider. Tubes may lose several pounds of pressure during this period. Under inflated tires roll slower, wear faster, and increase the chances of flats and rim damage.
If you're a racer then check tire inflation before each ride. When you train on the same tires, at the same pressure, as those you race on, you become a better and more confident bike handler.
Rotate your road tires regularly. The rear tire wears more than twice as fast as the front, so switch them every 1600 km or so to get maximum life from each pair.
Beware of using a gas station's air pump. It quickly delivers a large volume of air that can blow a bike tire off the rim.
Don t use a narrow tire on a wide rim. It reduces protection, upping the risk of damaging the rim when riding over potholes or rocks. Conversely, check that extra wide tyres will actually fit past your brake blocks!If you frequently bend or break hub axles, have the alignment of your frame's dropouts checked.

Repairing tires
The patches in most tube repair kits have foil on one side and clear plastic on the other. Carefully peel away the foil and place the patch against the tube after you've applied the glue. Leave the plastic on to prevent the patch from sticking to the inside of the tire. Don't forget to use the sandpaper supplied in patch kits to roughen the tyre and give the glue more surface area to hold onto.
Carry a patch kit as well as a spare tube so you won't be stranded if you have two flats on a ride.
Carry two spare tubes on a rainy ride. Flats seem to occur more frequently on wet roads, and it's difficult to apply patches in damp conditions.
Check the glue in your patch kit periodically to be sure it hasn't evaporated.
Glue-less patches make puncture repair quicker and simpler, but don t trust them to be a permanent fix. It s smart to replace a glue-less patch with a conventional one when you re back home.
Align the tire label with the tube s valve stem during installation. This looks pro, and if you have a puncture, it gives you a reference point. You can easily match the hole in the tube to the tire to check for embedded material. Small rocks or pieces of glass can remain hidden in a tyre for quite a number of punctures in a row - very frustrating - make sure you check your tyre well after a puncture.
Carry a tire "boot" in your patch kit to repair large cuts or sidewall damage. This could be a piece of clincher tire or canvas. Place it under the cut, between the tire and tube. (If need be, a piece of plastic from the side of the road or a folded business card will usually get you home) We like to call these "sleeves". They are only a temporary fix and can lead to more punctures if left in the tyre for a long period as edges rub on the tube.
That old standby, duct tape, can come in handy for cyclists. For example, it can be used like a boot (sleeve) to line the inside of a torn tire. Keep some wrapped around a tire lever in your seat bag.
If you're using tubular (sew-up) tires and change one on the road because of a flat, help the spare bond to the rim by heating the glue. Do this by riding for a few minutes with the brake lightly applied.

Theft
The first thing to do is buy a decent lock. Even if they are a bit expensive it is better than you bike going missing.
To confuse and perhaps foil a thief, adjust one brake so when its quick-release is closed it clamps the rim and prevents the wheel from rolling.
If your mountain bike has a quick-release seat post, remove it and secure it with your lock (or take it with you) when leaving the bike unattended.
Write your name, address, phone number, and "this bike was stolen" on a piece of masking tape and stick it to the fork's steerer tube. Then if the bike is ever stolen, then a shop mechanic may someday contact you in the midst of a repair and make your day.

New bikes
Check all nuts and bolts on a new bike after the first week of use. If anything is going to loosen, it'll usually happen during the initial miles. If you are worried about anything, please bring the bike back into the shop and let the mechanics have a look at it. The cables will stretch within a few months and so the gears will need to be re-adjusted if they are making any clicking noises or not working properly.