Know The Available Rim Tape Sizes
Rim tape comes in a wide range of sizes. The one you choose depends on the number of holes in your rim (spokes attach to these holes) and the size of those holes and the valve, along with your bike's rim size, or to be precise, the rim width. The size of your rim tape should match the size of your rim.
Two standard sizes are 1/8″ and 11/8″. Both are relatively narrow, but 11/8″ is slightly wider than 1/8″. These tapes are designed for rims with small spoke holes and narrow tires (up to about 25mm).
Other popular sizes are 13/8″ or 11/2″. These are wider than the previous two options but still not very wide overall. They're designed for rims with larger spoke holes and can be used with tires up to 30mm.
Measure The Tire Bead Seat Diameters
If you are unsure whether you need a wide or narrow type of rim tape, you'll have to find how large your rim tire beads sit in your rims.
To do this, measure from bead to bead across the inner surface of the rim. The measurement should be approximately 28mm – 47mm (1.10″ – 1.850″). This is called your tire bead seat diameter (TBSD) and will help you determine what width of rim tape is right for you.
When you have an older bicycle, particularly a racing bike, it might have sewn-up tires. Sew-up tires are glued directly onto the rim rather than an inner tube. On these bikes, the tire bead seat diameter will be larger than on a bike that uses clincher tires and inner tubes.
Measure Your Wheel's Rim Size
Determining the rim tape size becomes the easiest once you know your bike's rim width or the distance between the walls of your bike wheel. With this measurement, you can check the standard rim tape size chart and match the tape size you want to use without much guesswork.
To determine your rim size, you can look at the sidewall of your tire. The numbers will look like this: 700 x 23c. The "700" is the diameter of your wheel, and the "23" is the width. Both are measured in millimeters.
If there are no numbers on your tires, look at the front and back wheels. If they are the same size, you only need one length of rim tape. However, if they are different sizes (say, the front is 700 x 18c and the rear is 700 x 25c), you might need to order two different lengths of rim tape.
