Rotating chart for making track related gear calculations simpleSpin the perfect gear ratio, on the track or in the streets - reliable, accurate gear calculations for (700c wheel) track bikesAffinity did the math and created a simple, easy to use chart which generates 100% accurate calculations unlike inaccurate online calculatorsRotate the chart to choose your chain ring size, the window then displays the results of your chain ring & cog gear ratio based on 3 different tire sizes19 chain ring variants (47-65t) and 6 cogs (12-17t) for a total of 342 total calculationsGear CalculatorUPC/EAN/GTIN: 850014520496