Entering all relevant data:
Enter gearing data
manually for a bike not yet in the presets
Although a bike is not in the presets, you can still calculate its gearing if you know all the
relevant data and enter it manually in to the fields.
- Go to the main page
- Press the Reset button to clear all input.
- Start entering all these
Only field 'Tire Circumference' will be filled automatically after filling the
Rear Tire size fields
While not all
field are filled, you might get some strange values (like
NaN) in the resulting
tables and even in the fields you are entering:
Do not, worry it will be alright in the end.
Drive Ratio: this is the gear ratio between engine RPM and the clutch
shaft RPM. It has to be entered as a decimal number like '1.761'. So if the
User Manual says Primary Drive is '37/21', just calculate the result of 37
dived by 21 and enter the result (which is 1.761)
Size: The (Rear) tire size consists of 3 fields, the tire width in millimeter,
the tire height in % of tire width and the rim diameter in inches. Not very
consistent but that's the way tire manufacturers do it. An example is:
190/50/15. This means 190 mm wide, 50% of 190 mm and a 15"
rim. If your bike is older and has tires that uses another notation, you
convert those numbers to this notation and units.
Circumference: The previous 3 fields are used to calculate the rear tire
circumference which is used in all GC calculations. If you know that your
tire circumference is different from a default calculated one, you can
change the calculated one to your actual circumference. Make sure to use the
right units. More info on this:
Tire size and Circumference
This is the RPM where your bike delivers the most power. This RPM is often
referred to by "Maximum power xxx BHP @ xxxx RPM" and is the RPM present at the
top of the power curve. So try to find a bike review where these figures are
mentioned. It is NOT
the red-line RPM on
your rev counter
is it the RPM the rev limiter kicks in ! Also have a look at:
Max RPM discussion
Drive Ratio: The number of teeth on the front and the number of teeth on
the rear sprocket
Chain or Belt Pitch:
the pitch of the stock chain in millimeters. All 520, 525 and 530 chains
have a pitch of 15.875 mm (or 0.625 inch) If you're not certain, just
mention the chain type (like '525'). (Not mandatory but please check User
For belt driven bikes please enter the pitch (not the width) of
the belt. For most bikes this will be 14 mm but please try to find
Chain Links or Belt
Teeth: The number of links in the stock chain. (Not mandatory but please
try to find out in your user or service manual).
For belt drive bike
please enter the number of belt teeth of the stock belt.
Ratio: The number of teeth on the first gear cogwheels. Mostly these are
listed in the user or service manual as "37 / 13". This is the preferred way
as this is more accurate then supplying a rounded ratio.
The first field is used for the number of teeth of the wheel that the power
is being applied to, or in other words, of the wheel that is driving the
second wheel. The second field is used for the number of teeth of the wheel
that is being driven.
sometimes gear ratio is only listed as the real ratio, that is 37 divided by
13 = 2.846 If so, you can enter 2.846 in the first field en 1 in the second
field. This is not as accurate the other method (37 & 13) as it is rounded.
Here also the first field is used for the wheel that the power is being
applied to and thus is driving the second wheel.
Ratio - 7th Gear Ratio: The same way as the first gear ratio data was filled.
For Non-existing gears just enter 0 in both fields.
Fill all fields
until you have something like this:
- The first field of every Gear Ratio
(with blue border) is used for the number of teeth of the cog-wheel that the power is being applied to, or in other words, of the
cog-wheel that is driving the second wheel.
The second field (with red border) is used for the number of teeth of the
cog-wheelthat is being
In this example I changed from a 190/50/17 to a 180/55/17 tire and also from
a 15 to 14 front sprocket in Current setup and from a 36 to 39 rear sprocket
in Custom setup.
You have to
enter the value of the 'Chain Pitch' in 'mm' for now. When ready you can
switch to inches by selecting the Units radio button. Normally a 520 and 530
chain has a 0.625 inch pitch which in millimeters is: 15.875 mm
Select the correct units if needed
press the Reset button
- press the Load
Gearing or Load Personal button
- switch to another page and return or....................all
your input will be lost !
Just use the
calculator as intended, that is change various fields and see the results in
You can only save
a Personal Setup for bikes that are already in the database so that
button is grayed out when entering the data manually.
If you want to be able to save
& load Personal Setup's for a bike, send in the stock data (using the 'Add
Bike' option from the menu) to have me add it to the database.
Saving Personal Setup for future loading
Back to Gearing
Commander main page