In Version 2.2 onwards of the bicycle gear calculator there is a new separate pop up gear calculator that has been specifically tailored for the needs of single speed fixed wheel bicycle riders. If you are attempting to optimise your derailleur gears then your needs have always been very well catered for by the existing functionality of GearCalc Pro and the following information will not be of interest to you. If however you are a super hard macho cyclist looking to optimise a fixed wheel bike for a world record attempt or track race around the local velodrome then read on. This little calculator was designed specifically to cater for your needs 8-)
GearCalc Pro generates a list of all possible gearing combinations that fall within user defined ranges of ratios and sprocket teeth. The list is sorted in order of lowest ratio to highest making it easy to see all the possible combinations of sprocket tooth values that can be used to make exactly the same ratio and easy to pick out the appropriate gearing combination that gets closest to your desired optimum ratio. Optionally the list of gearing combinations can be restricted to include only the front cogs, sprockets or chainrings, and/or rear cogs/sprockets available in your bicycle spares box. GearCalc Pro also calculates the time required to ride a fixed distance along with the distance travelled in a fixed time for each gearing combination when riding at a constant cadence on your fixed wheel bike.
The display can be divided into two main areas. The control area on the left is where you enter your chosen parameters concerning ranges of gear ratios and sprocket teeth, target cadence and distance or time and preferred sprocket sizes. The output area on the right gives a table of ratios that satisfy the parameters.
GearCalc Pro's output is the table of numbers shown on the right side of the illustration above. From left to right the columns contain (headings in bold):
The gear calculators control area is divided into three panels, labelled range, targets and preferred sizes. Values can be entered directly or incremented deincremented courtesy of the usual convenient spin controls or by using the arrow keys on your computers keyboard.
There are three user defined ranges:
The cadence, distance and time settings are used to calculate the six columns on the right of the ratio column. Target cadence and time used to calculate the distance the bicycle will travel for each gear combination, and cadence and distance are used to calculate the time it will take. The RPM column uses target distances and times to calculate the implied cadence for each gear ratio to the nearest rev per minute. The units combo effects all three calculations so if you set it to miles the distances quoted in the table will be in miles, and the distance used to calculate time elapsed will be assumed to be in the same units. The two speed columns on the far right are calculated from your target cadence and overall gearing only.
Preferred sprocket sizes are typically the ones that are already available in your bicycle spares box! As chainrings (front sprockets) are considerably more expensive than back sprockets it is likely that the 'front' list will be more useful than the 'rear' list but both work in an identical fashion. Tick the checkbox and the program uses only the cog tooth values that appear in the drop down list instead of every possible value. To add a new value to the list just type it in and click the plus button (+), to remove simply select and click the minus button (-). When 'Override cog ranges' is checked values in the preferred list which fall outside the range specified above are used when it is unchecked they aren't.
If this option is checked and my bike power calculator is running GearCalc Pro will send the numbers of cog teeth on each sprocket and a calculated speed value across to the bicycle power calculator for further processing every time you move the highlight bar to a new position on the output table. PowerCalcs thrust calculator will even compute the force on the bikes pedals taking into account the terrain, prevailing wind, gearing, crank length, transmission efficiency and atmospheric conditions etc.
If this sounds far too easy you can always use some gear ratio charts or my super cool Abacus.
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