Enter gear ratios, primary ratio, sprocket sizes and tire diameter, then drag RPM slider to calculate speed from RPM.
Drag Max RPM slider to adjust the range of the RPM and Speedometer Gauges.

Enter Shift at RPM, select gear to shift to and hit Shift and Trace to run up through the gears recording shift point RPM and km/h - mph.

Check Compare Sprockets and enter alternate sprockets for comparison. The speedometer will display 1 needle for each sprocket set.
Or run Shift and Trace then hit Copy Diagrams to copy diagrams to page footer, edit and repeat to compare multiple combinations.

To calculate Chain Link adjustment to maintain rear wheel position when changing sprockets, use our Chain and Sprocket Calculator

Check the Compare Sprockets box, and drag the Front and Rear sprocket sliders to visually align different gears, and see all available gear spread combinations for different sprocket combinations.

Gear Spread Combination Options? For whatever reason you use your bike (racing etc) you may not need every gear available.
If you don't really need 1st gear (too low) or you never get into top (too high), you may be able to get a better gear ratio spread by changing sprocket combinations, and using different gear set selections.

Most motorcycle gearbox ratios get closer together as you go up through the gears.
So for example, if you have a 6 speed box, but only really need 5, you can make ➋ = ➊   or   ➎ = ➏ and change the gear spread by selecting different sprocket combinations, and using
➊-➋-➌-➍-➎   or   ➋-➌-➍-➎-➏   (Don't forget which gear to start in!)

Another example: Using 16/40 sprockets - 1st is too low, 6th is just right. Using 20/46 sprockets puts 5th where 6th was, and makes 1st taller (more legs off the line?). You only have 5 gears in the spread compared to 6 before, but if 5 will do, you've fixed the 1st gear too low problem.