Gear Calc

Misc. Downloads

Gear Inch Ratio Chart For 28 Inch Bicycle Wheel

The gear inch ratio for bicycles is defined as:
Inch ratio = wheel diameter * (front cog teeth / rear cog teeth)
Or putting it another way it is the diameter that a Penny Farthing wheel would need to be to produce the same gear ratio.

Back in the dark ages of cycling (before GearCalc Pro) riders actually used to optimise their bicycle gears this way! The trick is to choose front (chainring) and rear (freewheel/cassette) values that give an evenly spaced set of ratios in the correct range, that will produce also a simple gear shifting pattern. My bike gearing calculator can do this automatically of course, and a whole lot more besides. The gear inch table below is solely for the benefit of die hard traditionalists and masochists.

The numbers in represent the number of freewheel / cassette teeth. The blue numbers are chainring tooth values. The numbers in the white cells are inch ratios for a given chainring and freewheel. From experience I can tell you that less than four inches difference between two gears is barely a gear change at all, and more than twelve inches is starting to feel like a big jump. Personally I like to get as close as possible to eight inch steps between gears.

The cell with the yellow background (97 inches) is the gear size for a 52 tooth chainring cog combined with a 15 tooth rear cog.

FREEWHEEL OR CASSETTE REAR COG TOOTH VALUES

F
R
O
N
T

C
O
G

T
O
O
T
H

V
A
L
U
E
S

	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31	32	33	34
54	126.0	116.3	108.0	100.8	94.5	88.9	84.0	79.5	75.6	72.0	68.7	65.7	63.0	60.4	58.1	56.0	54.0	52.1	50.4	48.7	47.2	45.8	44.4
53	123.6	114.1	106.0	98.9	92.7	87.2	82.4	78.1	74.2	70.6	67.4	64.5	61.8	59.3	57.0	54.9	53.0	51.1	49.4	47.8	46.3	44.9	43.6
52	121.3	112.0	104.0	97.0	91.0	85.6	80.8	76.6	72.8	69.3	66.1	63.3	60.6	58.2	56.0	53.9	52.0	50.2	48.5	46.9	45.5	44.1	42.8
51	119.0	109.8	102.0	95.2	89.2	84.0	79.3	75.1	71.3	68.0	64.9	62.0	59.5	57.1	54.9	52.8	51.0	49.2	47.6	46.0	44.6	43.2	42.0
50	116.6	107.6	100.0	93.3	87.5	82.3	77.7	73.6	70.0	66.6	63.6	60.8	58.3	56.0	53.8	51.8	50.0	48.2	46.6	45.1	43.7	42.4	41.1
49	114.3	105.5	98.0	91.4	85.7	80.7	76.2	72.2	68.6	65.3	62.3	59.6	57.1	54.8	52.7	50.8	49.0	47.3	45.7	44.2	42.8	41.5	40.3
48	112.0	103.3	96.0	89.6	84.0	79.0	74.6	70.7	67.2	64.0	61.0	58.4	56.0	53.7	51.6	49.7	48.0	46.3	44.8	43.3	42.0	40.7	39.5
47	109.6	101.2	94.0	87.7	82.2	77.4	73.1	69.2	65.8	62.6	59.8	57.2	54.8	52.6	50.6	48.7	47.0	45.3	43.8	42.4	41.1	39.8	38.7
46	107.3	99.0	92.0	85.8	80.5	75.7	71.5	67.7	64.3	61.3	58.5	56.0	53.6	51.5	49.5	47.7	46.0	44.4	42.9	41.5	40.2	39.0	37.8
45	105.0	96.9	90.0	84.0	78.7	74.1	70.0	66.3	63.0	60.0	57.2	54.7	52.5	50.4	48.4	46.6	45.0	43.4	42.0	40.6	39.3	38.1	37.0
44	102.6	94.7	88.0	82.1	77.0	72.4	68.4	64.8	61.6	58.6	56.0	53.5	51.3	49.2	47.3	45.6	44.0	42.4	41.0	39.7	38.5	37.3	36.2
43	100.3	92.6	86.0	80.2	75.2	70.8	66.8	63.3	60.1	57.3	54.7	52.3	50.1	48.1	46.3	44.5	43.0	41.5	40.1	38.8	37.6	36.4	35.4
42	98.0	90.4	84.0	78.3	73.5	69.1	65.3	61.8	58.8	56.0	53.4	51.1	49.0	47.0	45.2	43.5	42.0	40.5	39.1	37.9	36.7	35.6	34.5
41	95.6	88.3	82.0	76.5	71.7	67.5	63.7	60.4	57.3	54.6	52.1	49.9	47.8	45.9	44.1	42.5	41.0	39.5	38.2	37.0	35.8	34.7	33.7
40	93.3	86.1	80.0	74.6	70.0	65.8	62.2	58.9	56.0	53.3	50.9	48.6	46.6	44.8	43.0	41.4	40.0	38.6	37.3	36.1	35.0	33.9	32.9
39	91.0	84.0	78.0	72.8	68.2	64.2	60.6	57.4	54.6	52.0	49.6	47.4	45.5	43.6	42.0	40.4	39.0	37.6	36.4	35.2	34.1	33.0	32.1
38	88.6	81.8	76.0	70.9	66.5	62.5	59.1	56.0	53.1	50.6	48.3	46.2	44.3	42.5	40.9	39.4	38.0	36.6	35.4	34.3	33.2	32.2	31.2
37	86.3	79.6	74.0	69.0	64.7	60.9	57.5	54.5	51.8	49.3	47.0	45.0	43.1	41.4	39.8	38.3	37.0	35.7	34.5	33.4	32.3	31.3	30.4
36	84.0	77.5	72.0	67.2	63.0	59.2	56.0	53.0	50.4	48.0	45.8	43.8	42.0	40.3	38.7	37.3	36.0	34.7	33.6	32.5	31.5	30.5	29.6
35	81.6	75.3	70.0	65.3	61.2	57.6	54.4	51.5	49.0	46.6	44.5	42.6	40.8	39.1	37.6	36.2	35.0	33.7	32.6	31.6	30.6	29.6	28.8
34	79.3	73.2	68.0	63.4	59.5	56.0	52.8	50.1	47.6	45.3	43.2	41.3	39.6	38.0	36.6	35.2	34.0	32.8	31.7	30.7	29.7	28.8	28.0
33	77.0	71.0	66.0	61.6	57.7	54.3	51.3	48.6	46.1	44.0	42.0	40.1	38.5	36.9	35.5	34.2	33.0	31.8	30.8	29.8	28.8	28.0	27.1
32	74.6	68.9	64.0	59.7	56.0	52.7	49.7	47.1	44.8	42.6	40.7	38.9	37.3	35.8	34.4	33.1	32.0	30.8	29.8	28.9	28.0	27.1	26.3
31	72.3	66.7	62.0	57.8	54.2	51.0	48.2	45.6	43.4	41.3	39.4	37.7	36.1	34.7	33.3	32.1	31.0	29.9	28.9	28.0	27.1	26.3	25.5
30	70.0	64.6	60.0	56.0	52.5	49.4	46.6	44.2	42.0	40.0	38.1	36.5	35.0	33.6	32.3	31.1	30.0	28.9	28.0	27.0	26.2	25.4	24.7
29	67.6	62.4	58.0	54.1	50.7	47.7	45.2	42.7	40.6	38.6	36.9	35.3	33.8	32.4	31.2	30.0	29.0	28.0	27.0	26.1	25.3	24.6	23.8
28	65.3	60.3	56.0	52.2	49.0	46.1	43.5	41.2	39.1	37.3	35.6	34.0	32.6	31.3	30.1	29.0	28.0	27.0	26.1	25.2	24.5	23.7	23.0
27	63.0	58.1	54.0	50.4	47.2	44.4	42.0	39.7	37.8	36.0	34.3	32.8	31.5	30.2	29.0	28.0	27.0	26.0	25.2	24.3	23.6	22.9	22.2
26	60.6	56.0	52.0	48.5	45.5	42.8	40.4	38.3	36.4	34.6	33.0	31.6	30.3	29.1	28.0	26.9	26.0	25.1	24.2	23.4	22.7	22.0	21.4