Clean the bicycle really well before work is done. Take the time to wash (and maybe even wax) the bike. It's time well spent.
When your tire with Schrader valve goes flat overnight seemingly for no reason, check to see if the valve core is not tight in the stem. Do this before removing the wheel from the bike and taking the tire off.
You put your seat back onto your bike and eyeballed it to get it straight, but when you ride the nose of the seat rubs one leg more than the other. When you put the seat back on, pull a piece of string taught from the center rear of the seat to the center of your stearer tube. This is much more precise than eyeballing it.
I had some heavy wheel bearing grease from the days when an automobile required the owner to repack the front wheel bearings periodically. I stirred a little motor oil into the grease until it was the right consistency for bicycle wheel bearings.
When replacing a flat, or just putting a tire together, rubbing talc powder in the tire will help prevent pinch flats.
Also, when putting a tire back on the rim, spraying the outside of the rim and the outside of the sidewall with Windex (or another quickly-evaporating liquid) will make your tire tool run more smoothly as you fit the tire back on.
When lacing a wheel, if you find that the second side spokes are too short/long (and you calculated the appropriate length beforehand), the initial spoke on the 2nd side is either in the wrong hole (hub or rim end), or facing the wrong direction.
Small clicks/rubs/etc that happen once per revolution aren't necessarily the drive train. Check your shoe laces, clip straps, tool pouch, streamers, computer to make sure you aren't hitting it.
If you are trying to take a cassette off, the easiest way is to mount the cassette/freewheel tool in a bench vice, place the wheel on the tool, and turn the wheel (like the steering wheel on a school bus).
When tightening pedals, you can use the crank arm and the wrench to make a fulcrum - this gives you great leverage.
And if you don't have talk, you can use cocoa powder- tested, and it works. Be it talk, or cocoa powder, I'd recommend rubbing it onto the tube. It's just simpler to do it evenly.
Do clean the wheel, especially the tire, before replacing or fixing/patching a tube. If you have the opportunity, wash it with with water, even. This will hopefully prevent dirt and debris to get inside the tire, which then may cause unexplained flats later on.
Geez, 36 posts and nothing about making sure the beer is cold (& plentiful).
What's the wrenching world coming to..?
The pin in my chain tool comes out and I could easily lose it. I always keep the tool and its pin in a sandwich bag.
I have a generic crank removal tool. I tried a small square of steel to keep the plunger from pushing into the threads for the crank bolt. My preference is a short piece of steel rod cut to length so its end protrudes a millimeter or so beyond the threads when inserted in the bolt hole. The diameter of the rod all but fills the hole for the bolt.
If you are confused about whether something, like a pedal, is right hand or left hand thread; just think about whether friction from its natural rotation in use would tighten or loosen the threads. Designers always make machinery so bolts naturally tighten a bit in use. No one wants their stuff falling apart for no good reason.
The binding collar from a rear reflector or a taillight is just enough to keep a slipping seat post from sliding down during a ride. Mount it just above the seat post collar.
Winter clothing with wicking properties is a lot cheaper in a common sporting goods department than at most bicycle supply houses.
Cotton Jersey gloves inside a larger than necessary pair of leather gloves keep hands warm in many winter termperatures.
Plastic food bags over your socks before you put your shoes on hold in a bit of extra warmth for your feet in the winter.
If you lose the instruction sheet or manual for a piece of equipment, it is probably available as a download somewhere on the Internet. Look at some catalogs. You may even see your unit with a different brand name on it. The manual may be available under the different brand name. My Schwinn cyclometer is also marketed as an Ascent. I was able to download a manaul for an Ascent that even looks exactly like my Schwinn manual.
WD-40 on a rag cleans up many greasy things on a bicycle.
An air tank is a great way to inflate bicycle tires. Just pump the tank up the the required pressure and there is no guessing about when the tire is at the proper pressure. Most air tanks have a pressure gauge on them.
For extra safety at night, cut some reflective tape to fit parts of your helmet and apply it. Some reflective tape is silver, not just red. (Some helmets claim adhesives could change the chemical composition of the protective material, but mine has not changed.)
Put a label on your helmet or your bike that gives your name, address, phone, blood type, and a contact number in case you are knocked unconscious in a crash.
When a bare brake cable flutters against the frame it makes a distracting noise. Get a piece of automotive vacuum hose an inch long. Slice it lengthwise in a spiral pattern. Wrap it around the cable near the middle of its run and tape the hose to the frame tube.
If your beer gets warm, fill a tray with ice and water, add a good amount of salt and then spin the cans or bottles in the tray. Icy cold in just a few minutes.
Better yet, just ride to the brewery.
What you have to realize is that while the crank is turning clockwise the bearing balls inside are rotating the opposite way and that motion tends to keep the cup tight.
There's a noise while turning the handlebars, but it isn't the headset. In fact, you're not even on the bike, and yet, there's still noise when the handlebars turn.
One possible source could be the brake cables rubbing against each other. And a possible solution is to apply a very little bit of chain oil where the cables touch.
From another thread: you patched your tube, but the patch leaks? It wouldn't stick properly (or at all)?
I had a few patches that wouldn't stick. Then I learned to clean the tube around the puncture with alcohol, and since then, all patches lasted forever. If you don't have a little bottle with alcohol with you while riding, a solution might be a little packed wet tovel (like those you get in the plane). Make sure the area around the puncture is perfectly dry and, above all, without grease. Any amount of grease or dust will cause the patch not to stick.
Also, remember to wait for the glue (or "cement") to dry, before placing the patch over it, and then push on it like you're possessed.
If it's stuck, get the Dremel.
If you're stuck on a plane, those little bottles of alcohol can lubricate you to a happy state.
Besides, in the example I cited, there doesn't need to be any weight on the handlebars and front wheel, the noise will still be produced. So, there are various ways to distinguish "my" case from "yours".
If the saddle has an ergonomic split, you can just lay a broomstick in the groove and line it up with the steerer, or kneel behind the bike and sight down the centerline of the groove until it's centered on the steerer (this might also work using the seat rails as a guide...I'm not sure)
My tip: WD-40 is a Water Displacer, not a penetrating oil. For stuck parts, get some Kroil or PB B'Laster.