Gear Inch Chart

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Gear Inches are used to give a numerical value to how a particular chainwheel/cog combination will feel.

Classic BMX gearing evolved over the years to be 44/16, which has 55 gear inches. The most popular gear ratios are pretty close to a 55 inch, which just seems to feel best for most people. The number is derived from a simple formula: (chainring size divided by cog size) multiplied by wheel size.

Gear Inch Chart - 24" Wheel

Gear Inch Chart 24 Inch Wheel

Gear Inch Chart - 20" Wheel

Gear Inch Chart 20 Inch Wheel

BMX 24 Inch Wheel BMX 20 Inch Wheel

Gear Inch Chart , 24" Wheel
BMX 24" Wheel
		9	10	11	12	13	14	15	16	17	18

23		61.3	55.2	50.2	46	42.5	39.4	36.8	34.5	32.5	30.7
24		64	57.6	52.4	48	44.3	41.1	38.4	36	33.9	32
25		66.7	60	54.5	50	46.2	42.9	40	37.5	35.3	33.3
26		69.3	62.4	56.7	52	48	44.6	41.6	39	36.7	34.7
27		72	64.8	58.9	54	49.8	46.3	43.2	40.5	38.1	36
28		74.7	67.2	61.1	56	51.7	48	44.8	42	39.5	37.3
29		77.3	69.6	63.3	58	53.5	49.7	46.4	43.5	40.9	38.7
30		80	72	65.5	60	55.4	51.4	48	45	42.2	40
31		82.7	74.4	67.6	62	57.2	53.1	49.6	46.5	43.8	41.3
32		85.3	76.8	69.8	64	59.1	54.9	51.2	48	45.2	42.7
33		88	79.2	72	66	60.9	56.6	52.8	49.5	46.6	44
34		90.7	81.6	74.2	68	62.8	58.3	54.4	51	48	45.3
35		93.3	84	76.4	70	64.6	60	56	52.5	49.4	46.7
36		96	86.4	78.5	72	66.5	61.7	57.6	54	50.8	48
37		98.7	88.8	80.7	74	68.3	63.4	59.2	55.5	52.2	49.3
38		101.3	91.2	82.9	76	70.2	65.1	60.8	57	53.6	50.7
39		104	93.6	85.1	78	72	66.9	62.4	58.5	55.1	52
40		106.7	96	87.3	80	73.8	68.6	64	60	56.5	53.3
41		109.3	98.4	89.5	82	75.7	70.3	65.6	61.5	57.9	54.7
42		112	100.8	91.6	84	77.5	72	67.2	63	59.3	56
43		114.7	103.2	93.8	86	79.4	73.7	68.8	64.5	60.7	57.3
44		117.3	105.6	96	88	81.2	75.4	70.4	66	62.1	58.7
45		120	108	98.2	90	83.1	77.1	72	67.5	63.5	60
46		122.7	110.4	100.4	92	84.9	78.9	73.6	69	64.9	61.3
47		125.3	112.8	102.5	94	86.8	80.6	75.2	70.2	66.4	62.7
48		128	115.2	104.7	96	88.6	82.3	76.8	72	67.8	64
49		130.7	117.6	106.9	98	90.5	84	78.4	73.5	69.2	65.3

Gear Inch Chart , 20" Wheel
BMX 20" Wheel
		9	10	11	12	13	14	15	16	17	18

23		51.1	46	41.8	38.3	35.4	32.9	30.7	28.8	27.1	25.6
24		53.3	48	43.6	40	36.9	34.3	32	30	28.2	26.7
25		55.6	50	45.5	41.7	38.5	35.7	33.3	31.3	29.4	27.8
26		57.8	52	47.3	43.3	40	37.1	34.7	32.5	30.6	28.9
27		60	54	49.1	45	41.5	38.6	36	33.8	31.8	30
28		62.2	56	50.9	46.7	43.1	40	37.3	35	32.9	31.1
29		64.4	58	52.7	48.3	44.6	41.4	38.7	36.3	34.1	32.2
30		66.7	60	54.5	50	46.2	42.9	40	37.5	35.3	33.3
31		68.9	62	56.4	51.7	47.7	44.3	41.3	38.8	36.5	34.4
32		71.1	64	58.2	53.3	49.2	45.7	42.7	40	37.6	35.6
33		73.3	66	60	55	50.8	47.1	44	41.3	38.8	36.7
34		75.6	68	61.8	56.7	52.3	48.6	45.3	42.5	40	37.8
35		77.8	70	63.6	58.3	53.8	50	46.7	43.8	41.2	38.9
36		80	72	65.5	60	55.4	51.4	48	45	42.4	40
37		82.2	74	67.3	61.7	56.9	52.9	49.3	46.3	43.5	41.1
38		84.4	76	69.1	63.3	58.5	54.3	50.7	47.5	44.7	42.2
39		86.7	78	70.9	65	60	55.7	52	48.8	45.9	43.3
40		88.9	80	72.7	66.7	61.5	57.1	53.3	50	47.1	44.4
41		91.1	82	74.5	68.3	63.1	58.6	54.7	51.3	48.2	45.6
42		93.3	84	76.4	70	64.6	60	56	52.5	49.4	46.7
43		95.6	86	78.2	71.7	66.2	61.4	57.3	53.8	50.6	47.8
44		97.8	88	80	73.3	67.7	62.9	58.7	55	51.8	48.9
45		100	90	81.8	75	69.2	64.3	60	56.3	52.9	50
46		102.2	92	83.6	76.7	70.8	65.7	61.3	57.5	54.1	51.1
47		104.4	94	85.5	78.3	72.3	67.1	62.7	58.8	55.3	52.2
48		106.7	96	87.3	80	73.8	68.6	64	60	56.5	53.3
49		108.9	98	89.1	81.7	75.4	70	65.3	61.3	57.6	54.4

Holograph