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Bicycle Glossary - G


Gearing - The multiplication of speed at the rear wheel due to the sprocket(s) at the crank being larger than the sprocket(s) at the rear hub. Gearing is measured in "inches" like so: Number of teeth on front sprocket, divided by number of teeth on rear sprocket, times diameter of the rear wheel in inches. This is a nominal figure, because pi is not part of the formula. If you multiply the result by pi, then the number you get is the number of inches actually traveled for each revolution of the crank. 

Generator set - A system in which a small wheel runs against the tire and turns a generator which creates electricity to power a headlight. Generator sets usually include a red taillight also. Generators have also been built into front and rear wheel hubs. Generator sets slow you down, but you never need batteries. 

Gooseneck - a colloquial term for handlebar stem.

Gram - A unit of weight.  There are approximately 28 grams in an ounce.

Graphite - 1. A form of carbon that's generally black and powdery and has good lubricating qualities.  Sometimes chain lubricants include graphite in their mixture.  Graphite by itself will not work into the internal areas of a chain, and does not stay in place, but lubricates well when mixed with a viscous fluid. 2. 'Graphite' can mean a carbon-fiber material that is light and strong, and sometimes used as the primary material in competition-quality bike frames.

Grease - A lubrication which does not drip. See Lubrication for more details.

Grease tattoo - An oily, black mark left on the rider's leg from touching the chainwheel. Synonym: Chainring tattoo.

Grips - Synonym: Handgrips.

Guide Pulley (pull' ee) - 1. The top of two small wheels on a rear derailleur which take up excess chain slack. The guide pulley helps guide the chain when gears are shifted. Most derailleur pulleys have friction bearings that work best and last longest if disassembled and greased now and then. A few have ball bearings. 2. A bracket containing a small grooved wheel that guides a control cable inner wire around a bend. See also: Tension pulley.

Gumwall tires - Tires that have a natural gum rubber sidewall, or tires that have a synthetic sidewall that looks like gum rubber. When gum rubber (or synthetic) is flexed, it returns with more energy than the typical black tire rubber, so you get a more efficient ride. However, gumwall tires are damaged from long-term exposure to the sun. Bicycle tires are usually black because carbon is added to reduce wear. Tires that are all gum would wear out quickly. 


Anything missing or need greater coverage? Let me know - Jeff

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Although I have attempted to cover the major safety issues, I cannot be responsible for your use of this information. Working on bicycles is dangerous if you do it without considering consequences of bolts left loose, known problems which are ignored, things which should be replaced but are glued instead, and so on. Proceed carefully at your own risk and use common sense. Jeff Napier, and all agents associated with this information, do not offer any guarantee or warranty for your use of this information.

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