Assessment Of Bicycle Gearing

Click the Assessment button in the cadence calculator, or gear usage table to produce an assessment in accordance with the gear usage table. You can produce as many assessments as you like, and these can be compared side by side. If you want to close the old assessment every time you create a new one, the multiple assessment feature can be turned off (or back on again) by selecting Multiple Assessments from any of the View menu's.

Gearing assessment showing table of values

You can move the highlight bar by clicking on the table, or by using the arrow keys on your keyboard. GearCalc Pro will automatically show you which gear this corresponds to in the main window.

When the assessment form is opened, the program calculates the narrowest cadence range possible with the current gears. The range is centered around the value (85 rpm) specified in the cadence calculator and gear usage table. First the speeds are calculated at your target cadence in the highest and lowest gears. Then for all speed values in this range, in steps of 0.1kmh, the program repeatedly finds the best gear and remembers the biggest differences above and below your target cadence.

The average step will be quoted in terms of the difference in either the inch ratio, or metre ratio between the gears. Also the standard deviation is quoted (1.21 inches in the example above).

From left to right the table shows:

Gear number
Front (Chainring number) & teeth
Rear (Freewheel number) & teeth
The step (inch or metre ratio) between the current and next lower gear.
Recommended speed to change down
Recommended speed to change up
Recommended cadence to change down
Recommended cadence to change up

The 'step' column is great for fine tuning the cog values in your group-set. Also I have been using the list of gear change speeds, to judge cadence against the speed display on my cycle computer. By setting the target cadence in the cadence calculator to 85 rpm, my 'up-change' speeds all come out close to 90 rpm. With any bike this is a ragged edge - some gears it pays to rev out a little more before changing up. I copy the column of 'up-change' speeds onto a slice of floppy disk sticker with a ball-point pen (because the ink doesn't run when it rains), add two horizontal lines to denote chain ring changes, and stick it on my handlebar stem next to my cycle computer. I used to use a cadence meter but my current cycle computer lacks this feature (it has a heart rate meter instead). Anyhow my speedometer gives the nearest tenth, and responds quickly. My cadence meter gave the nearest integer (and responded relatively sluggishly), so this is a more accurate (but less convenient) way to optimize cadence. It works well, but don't forget to look where you are going too!

When the Update rpm button is clicked, the lower cadence limit is rounded down to the nearest whole rpm and the upper limit is rounded up. These values are then inserted into the maximum and minimum cadence boxes in the gear calculators main window and its table and graph are recalculated.

Print This rather insignificant looking option provides printed certification for a bikes behavior, in terms of its gears. The printed assessment includes all the data from the assessment table, and details of the average step, target cadence, speed range, for the current cadence range, tyre size, details from the gear usage table, and comments. It provides something really nice to show your local builder of custom cassette's. This is the only print option needed. Users are reminded that the current rate of deforestation makes the 'paperless office' very desirable, and it will be located right next door to the paperless toilet.

The View menu offers the table above and also a couple of graph plotting options:

Speed differences shows the ideal speed at which the rider should change up.
Gearchange speed graph The closer this is to a straight line the better. You can stretch the scale by re-sizing the window - both of the assessment graphs will automatically re-size to fit.
If you are using a double or triple cog chainring then this turns the 'saw tooth' graph in GearCalc's main window into a streight line by simply not plotting the unused gears.

Ratio differences: The size of the bars represents the 'size' of each gear change in your chosen sequence.
Gear ratio differences bar chart

If they are all about the same height, then all the gears will feel the same distance apart. Use this to fine tune your values. The data comes from the 'step' column in the table, but this is probably quicker to interpret.

Setup Information
Snapshot of setup information used in gearing assessment Each assessment window is a stand alone module. When an assessment window is opened a snapshot of the information in the other windows is created. This information can be viewed here. A copy of the chain alignment diagram will only appear if you have used the suggest feature in the gear usage table. Also a last chance to change the comments is offered here. Text added here will be printed with the assessment and remembered until the window is closed. Click the Assign Comment button and you will assign the comment to the parent (main) window where it can be saved along with any other changes if you choose to do so. If the assessment window relates to a different file to the main window then you will be offered an additional choice where the comment can be saved directly with the data for the assessment file on your hard disk. Try it for your self - it is easier to use than to explain!

Bicycle Gear Calculator
Cadence Calculator
Cadence Optimisation On The Road
gear usage table
Gear Calculator For Single Speed Fixed Wheel Bicycles
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