How to change a flat tire:

How to lube your chain.  Note that Rock N Roll Gold lube is a great all around lubricant.  In performance tests, it has been shown to have one of lower friction losses, meaning more of the watts generated by your legs are turned to bike speed. Lubing your chain is easy, and should be done regularly to keep you bike operating efficiently and prolonging the life of your chain, cassette and chainrings. 

Removing an old chain and installing a new chain.

Installing a Garmin Speed and Cadence Sensor:

Adjusting the bicycle headset.  Understanding how to remove and relocate your stem (and handlebars) is important if you want to lower or raise your handlebars for better fit or aero improvements.

An overview on adjusting handlebars and aerobars for better comfort and performance.

An overview of adjusting bike seats.

Installing bicycle shoe cleats.

1 Hour Bike Tuneup.  Includes a lot of links to the associated detailed videos.