v7 sub

Generic Final Drive Ratio graph

The final ratio is the ratio between the front- and the rear-sprocket and is called final as it is last in line in the total gearing setup of engine to gearbox, gearbox to front sprocket and front- to rear-sprocket.

Since the final drive is the easiest and cheapest to change, it it often used to change the behavior of a bike. Changing this ratio changes both torque and speed of the bike, no matter if front or rear or both are changed, what counts is, is the ratio getting bigger or smaller.

Bigger   ratio results in: More Torque and Less Top Speed
Smaller ratio results in: More Top Speed and Less Torque.

In this graph you can see what changing a sprocket does for the ratio and thus for the Torque and Top Speed.
It can also be used to find an similar or (nearly) equal ratio when a specific ratio is needed but you don't have the right sprockets.

Say you need 47/16 (2.938) but don't have that and do not want to buy more sprockets.
Now set 47/16 in the custom setup (for any bike in the db), create this chart, see your ratio in the middle and go left and right until you cross one of the colored lines. If you cross one on exactly the same height, you have an exact match but this is unlikely to happen. If you need to go up or down a little you nearly have a match. In this example you will find 44/15 (2.933) and 50/17 (2.941) to be very close to the wanted 2.938.
This means if you have one of these sprocket combinations still lying around somewhere you can use it with (nearly) the same Torque and Top Speed results.

But beware that not all combinations are suited for fitting on the bike. Make sure there is enough clearance for the sprockets, enough chain length available and enough clearance for the chain not to touch the swing arm in the front. What changing to another sprocket combination does to your chain geometry can be seen in table: "Chain geometry changes due to sprocket & chain changes".

By hovering the cursor over the crossing of grid lines and colored Rear teeth lines, the ratio, front teeth and rear teeth are shown.

If you want to display the graph for other ratios, change the Custom setup final ratio on the main page. This chart is not related to any other bike specific settings, just the Front- and Rear sprockets in Custom setup (which are shown in the graphs sub-title) ! So this final ratio graph is valid for any bike, hence the title 'Generic'.

You can print the graph clicking the 'Print Graph'-botton. When printing to an installed 'print to pdf'-printer, you can save the graph as PDF-file.

Next: RPM Differences Graph

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