If you're looking for replacement parts for your bike, the best way to be sure we find the right match is to bring your whole bike in. The second best way is to bring in the affected parts and any parts that interact with them. Third best is to bring good pictures of the bike, with zoomed-in views of the parts you're trying to replace.
Below is a list of some of the most common replacement/wear parts on a bicycle, and how to identify what you have.
What tubes and tires do I need?
1. Know your valve type. The two common bicycle valve types are Schrader and Presta. Schrader valves are the same valves as on car tires. Presta valves are smaller and have a threaded tip to open and close the valve. Most common tube sizes come in either valve type.
2. Find your tire size. Usually this is listed on the sidewall of the tire, often in more than one format. For instance, the tire may have "700X28c" printed in one spot and have "(28-622)" or "(622-28)" embossed in the rubber elsewhere. The two-digit and three-digit numbers in parentheses are called the ISO size. The three-digit number is a standard marking for rim sizes. Most tires from the last twenty years have the ISO size, and it is a more certain way of knowing rim size for buying tires. (For example, there were several different rim sizes called "26 inch" over the years - including ISO sizes 559, 584, 590, and 597. A 590 ISO won't fit a 559 rim, and vice-versa.) The two-digit number from the ISO size is a standard tire width measurement, roughly in millimeters; the "(28-622)" example above is about 28mm (or 1-1/8") wide on a common rim.
If you don't mind starting down a virtual rabbit hole, Sheldon Brown had an article on tire sizing - among many other topics of the bicycle world.
What brake pads do I need?
1. Find out if your brake pads run on the rims of the wheel or on a disc rotor near the hub.
2. If the pads run on the rim, there are a few common types: road caliper blocks, road pad inserts, smooth-post cantilever pads, threaded-post V-brake (or linear-pull) pads, and pad inserts for V-brakes. Pads for the right type of brake usually fit many different manufacturers' brakes. Having the bike, brakes, or pads at hand reduces the guesswork.
When replacing worn rim brake pads, check the braking surface of the rim for damage or wear - especially if there are bits of metal in the old brake pads. Rim braking surfaces usually start out as a fairly flat surface. As they wear, they can become concave, gouged, or even cracked.
3. If you have disc brakes, find the manufacturer and model. Usually these will be printed somewhere on the brake caliper. Some inexpensive disc brakes will have no clear markings anywhere, and you'll need to get the pads out to try to match them. Luckily, many of the nameless, cheaper disc brakes are made by the same factories as bigger brands or are such close copies of bigger brands that a common pad might work.
Many disc brakes also have more than one pad compound available. Usually the pad compound is only marked on the pads themselves. The disc rotor may also be marked with something like "Resin Pads Only," which means the manufacturer designed it to work only with certain pad compounds.
Rotors often wear more slowly than pads, but they may need to be replaced along with pads - especially if they've been bent or contaminated with anything oily or greasy.
What chain do I need?
1. Count the number of gears on the rear wheel. Chains are usually designed as part of set of components and are sized and shaped to work with certain numbers and types of rear cogs.
2. Find the manufacturer of the current chain or of the rest of the shifting parts. Often the side plates of the chain will be stamped with a manufacturer logo and/or model name for the chain. Knowing the make and model of the shifters and derailleurs can also help identify compatible chains. Some of the most common chain makers are Shimano, SRAM, KMC (often just stamped with a "Z" logo), Campagnolo, and Wippermann.
3. Chains and rear cogs (sometimes called cassettes or freewheels) mostly wear together as sets. Front chainrings generally wear more slowly, but they wear out, too. Often replacing a chain by itself can lead to gear skipping or slipping on worn cogs or rings. There are tools available to check chain wear, and we usually keep some in stock.
For more on identifying rear gears, look below or click here.
What rear gears do I need?
1. Count the number of cogs.
2. Identify the way the gears attach to the hub. There are several types of rear gear clusters for different hub types. Having the gear cluster and rear wheel at hand helps to identify what you have. There are part-specific tools for removing or installing different types of clusters. We keep some of the common tools in stock for do-it-yourselfers.
3. Count the number of teeth on the smallest and largest cogs of the cluster. Most freewheel or cassette types will come in more than one size/range of gears. The different sizes are usually listed as something like "11-32." That means 11 teeth on the smallest cog, 32 teeth on the largest. Sometimes the shifters and derailleurs can accept a few different ranges of rear gears, but knowing what you have is a good starting point.