GeRZ Bicycle Gear Tables -- How To Use (2)

Improve Your Bike's Gearing With GéRZ -- Directions Page Now Loading Below

GéRZ (Say "GEARS") Bicycle Gear Tables || http://home.i1.net/~dwolfe/gerz/ || dwolfe@i1.net

-- CHAINRING TEETH --

C
A
S
S
E
T
T
E

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F
R
E
E
W
H
E
E
L

T
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54.0

58.9

63.8

68.7

73.6

78.5

83.4

88.4

93.3

95.7

98.2

103.1

108.0

112.9

117.8

122.7

127.6

130.1

How To Use GéRZ Bicycle Gear Tables (2)

Review the common gearing problems illustrated below, then trouble-shoot your own gears keeping the "Elements of an Efficient Drivetrain" in mind. Explore improved setups by creating additional gear charts using ratios for new chainring and/or cassette/freewheel combinations from the GéRZ Bicycle Gear Tables. (See note below.)

When setting up a new bike, take a test ride in your chosen terrain to establish bottom- and top-end gear ratios that sufficiently meet your needs. Reference the GéRZ Bicycle Gear Tables and choose chainring and rear cog sizes that provide these "outer" ratios, as well as suitable intermediate gears. (See note below.)

Evaluate Your Gears
1. Study the Example 2 and Shift Pattern charts and description below for a sampling of typical problems that affect gearing function.

Example 2

Shift Pattern

For Example 2, which represents the gear range found on a 16-speed, high-performance bike with 700C wheels, the charts indicate:

Nearly duplicated gear ratios in the 39/17 and 53/23 combinations.

Double shifting throughout the middle gear range.

A large gap between the 95.4 and 110.1 gears.

NOTE: "Crossover gears" formed by the 39/12 and 53/25 combinations have not been included in this shift pattern. Due to added wear caused by the extreme chain angles created by these gears, their regular use is not recommended.

2. Review the gear chart you just created (see "How To Use (1)") and plot your shifting pattern from low to high as in the Shift Pattern chart above.

3. Note any problems and make a few new charts with other gear combinations that improve the gearing shortcomings. For Example 2, if the rider can use a bit higher first gear, replacing the rear cogs with a 12-23 setup will solve several problems. See Example 3 charts below.

Example 3

Shift Pattern

Limited gear duplication still remains in Example 3, but in comparison to Example 2, these charts reflect:

Much less double shifting.

A closed gap between the 95.4 and 110.1 gears.

CONCLUSION: Although these examples deal only with relatively high gearing suitable for racing and other performance riding, they illustrate that a gear check and minor equipment changes can often help riders of all styles improve the efficiency of their bicycles.

Casual riders, for example, may consider installing a smaller outer chainring or rethinking their rear cog range for a lower top end. Many stock gear setups include gear ratios that are needlessly high for recreational uses.

NOTE: Chainring and cassette/freewheel sizes in GéRZ Bicycle Gear Tables present typical selections for both road and off-road bicycles. Not every size will fit your equipment. Before you invest time planning your "perfect" gear setup, contact your bike shop and/or component manufacturers for info on specific gearing options available to fit your bicycle.

PRINTING NOTE: For best results, reduce or print pages horizontally. <Gear ratios shown are approximate.> For other gears or greater accuracy, multiply drive wheel diameter in inches by number of chainring teeth, then divide by number of teeth on rear cogs for individual ratios.

27" / 700C Gérz
26" Gérz Chart
How To Use (1)