Unusual types of gramophone records Unusual types of gramophone records The overwhelming majority of records manufactured have been of certain sizes (7, 10, or 12 inches), playback speeds (33, 45, or 78 RPM), and appearance (round black discs). However, since the commercial adoption of the gramophone record (called a phonograph record in the U.S., where both cylinder records and disc records were invented), a wide variety of records have also been produced that do not fall into these categories, and they have served a variety of purposes. The most common diameter sizes for gramophone records are 12-inch, 10-inch, and 7-inch. Early American shellac records were
Gear inches of the drive wheel; that is, it is like a directly driven bicycle with a 52-inch wheel. That gear is said to be "52 gear inches." A bicycle with a 26-inch wheel, a 48-tooth chainring, and a cassette with gears ranging from 11 to 34 teeth has a lowest gear of 26 × 48 / 34 = 37 gear inches and a highest gear of 26 × 48 / 11 = 113 gear inches. For bicycles with 700c wheels, some cyclists quote gear inches based on a nominal wheel diameter of 27 inches, corresponding to the old British tire size