Bicycle gear calculator running at http://gear-calculator.com and http://ritzelrechner.de
When buying a new bike or upgrading an old one the gear calculator can help to find the optimal gearing for it. The gear calculator displays graphically the speed and development (either in gear inches or in meters) for all gears of a given gearing system, either with derailleurs or with hub gears. Gearing system, chainrings and cogs can be chosen out of given lists or selected by moving the sprocket symbols. Not used chainwheels and cogs can be removed by moving them to the left below the graphics. The tire size can be chosen out of a list or the tire circumference can be entered in millimeters.
The gear calculator is built with OpenUI5 (http://openui5.org)
Currently English, German, French, Spanish and Hungarian language is supported. Any help for other languages is appreciated.