The rear derailleur is designed to move the chain up and down on the sprockets (or cogs) connected to your rear hub. Together these cogs are known as the rear cassette. By moving to a cog with fewer teeth, the derailleur gives the rider a faster (or higher) gear which is appropriate for flat areas or descents. By moving to a cog with more teeth, the derailleur offers a gear more appropriate for climbing hills (or a lower gear).

A freehub is attached to the rear hub of your bicycle. It is a spinning mechanism designed to hold the cassette. Coasting when the pedals are at rest and pedaling are possible thanks to the freehub.

Start by removing the cassette. To remove the cassette:

A chain “stretches” through regular use. This does not mean the metal literally stretches, but over time the bushings between the plates of the chain wear down, and the chain becomes a little longer. “Stretch” is the main reason avid cyclists replace their chains, but if your chain is rusty or just plain ol’ grimy, it’s not a bad idea to replace it.

A freewheel makes it possible to coast on a bike. When you are pedaling, the freewheel engages the sprockets, but it allows the rear wheel to turn when the pedals are at rest.

- A bicycle stand is always recommended
- A special tool designed specifically for your particular freewheel, known as a “freewheel puller”
- An adjustable wrench compatible with the hexagonal section of your freewheel puller
- You may need a bench-mounted vice for particularly stubborn freewheels

Lift your wheel off the ground and give it a spin. If the wheel wobbles back and forth or up and down, it’s time to true it. Wheels come out of true through regular use. The rim is held at the correct angle to the hub by the pull of the spokes in equal directions. Hopping curbs, hitting rocks and the general punishment a bicycle endures is enough to knock a wheel out of true.

Keeping your chain clean is essential, especially if you ride in the rain or other adverse weather conditions. Regular chain maintenance prevents rust and chain stiffness.

There are two camps in the debate over chain lubrication: proponents of lubrication and its opponents. The opponents’ argument is based on the idea that chain lubricants attract grime. When this grime becomes stuck to the chain, the opponents of lubrication believe it causes increased chain wear.

The camp promoting chain lubrication believes lubricants allow for longer chain life and reduced friction. There is little evidence to settle this debate. For more information about lubricating your chain, read on.