Gear calculator.

Chainring, cog and cadence in. Ratio, rollout, gear inches and speed out.

Pick a chainring and cog, set your cadence, and see what that gear gives you. The table lists every combination from 46–55T by 13–17T at the same cadence, so you can compare gears before race night. Figures assume a 700c wheel with a 23mm tire (2.096 m rollout per wheel revolution).

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Chainring

50T

Cog

15T

Cadence90 rpm

Gear ratio: 3.33
Rollout: 6.99m
Gear inches: 90.0in
Speed: 37.7km/h

Ratio: 50 ÷ 15 = 3.33
Rollout: 3.33 × 2.096 m = 6.99 m
Gear inches: 3.33 × 27.0 in = 90.0 in
Speed: 6.99 m × 90 rpm × 60 ÷ 1000 = 37.7 km/h

Every chainring and cog combination, smallest gear first. Speed at 90 rpm.
Cog	Ratio	Gear inches	Rollout (m)	Speed at 90 rpm (km/h)
17T	2.71	73.1	5.67	30.6
17T	2.76	74.6	5.79	31.3
17T	2.82	76.2	5.92	32.0
16T	2.88	77.6	6.03	32.5
17T	2.88	77.8	6.04	32.6
16T	2.94	79.3	6.16	33.2
17T	2.94	79.4	6.16	33.3
16T	3.00	81.0	6.29	34.0
17T	3.00	81.0	6.29	34.0
17T	3.06	82.6	6.41	34.6
16T	3.06	82.7	6.42	34.7
15T	3.07	82.8	6.43	34.7
17T	3.12	84.2	6.53	35.3
16T	3.13	84.4	6.55	35.4
15T	3.13	84.6	6.57	35.5
17T	3.18	85.8	6.66	36.0
16T	3.19	86.1	6.68	36.1
15T	3.20	86.4	6.71	36.2
17T	3.24	87.4	6.78	36.6
16T	3.25	87.8	6.81	36.8
15T	3.27	88.2	6.85	37.0
14T	3.29	88.7	6.89	37.2
17T	3.29	88.9	6.90	37.3
16T	3.31	89.4	6.94	37.5
15T	3.33	90.0	6.99	37.7
17T	3.35	90.5	7.03	37.9
14T	3.36	90.6	7.04	38.0
16T	3.38	91.1	7.07	38.2
15T	3.40	91.8	7.13	38.5
17T	3.41	92.1	7.15	38.6
14T	3.43	92.6	7.19	38.8
16T	3.44	92.8	7.21	38.9
15T	3.47	93.6	7.27	39.2
17T	3.47	93.7	7.27	39.3
14T	3.50	94.5	7.34	39.6
16T	3.50	94.5	7.34	39.6
17T	3.53	95.3	7.40	39.9
15T	3.53	95.4	7.41	40.0
13T	3.54	95.5	7.42	40.0
16T	3.56	96.2	7.47	40.3
14T	3.57	96.4	7.49	40.4
15T	3.60	97.2	7.55	40.7
13T	3.62	97.6	7.58	40.9
16T	3.63	97.9	7.60	41.0
14T	3.64	98.4	7.64	41.2
15T	3.67	99.0	7.69	41.5
16T	3.69	99.6	7.73	41.7
13T	3.69	99.7	7.74	41.8
14T	3.71	100.3	7.79	42.0
15T	3.73	100.8	7.83	42.3
16T	3.75	101.3	7.86	42.4
13T	3.77	101.8	7.90	42.7
14T	3.79	102.2	7.93	42.8
15T	3.80	102.6	7.96	43.0
12T	3.83	103.5	8.03	43.4
13T	3.85	103.8	8.06	43.5
14T	3.86	104.1	8.08	43.7
15T	3.87	104.4	8.10	43.8
12T	3.92	105.8	8.21	44.3
13T	3.92	105.9	8.22	44.4
14T	3.93	106.1	8.23	44.5
15T	3.93	106.2	8.24	44.5
12T	4.00	108.0	8.38	45.3
13T	4.00	108.0	8.38	45.3
14T	4.00	108.0	8.38	45.3
15T	4.00	108.0	8.38	45.3
14T	4.07	109.9	8.53	46.1
13T	4.08	110.1	8.55	46.1
12T	4.08	110.2	8.56	46.2
14T	4.14	111.9	8.68	46.9
13T	4.15	112.2	8.71	47.0
12T	4.17	112.5	8.73	47.2
11T	4.18	112.9	8.77	47.3
14T	4.21	113.8	8.83	47.7
13T	4.23	114.2	8.87	47.9
12T	4.25	114.8	8.91	48.1
11T	4.27	115.4	8.96	48.4
14T	4.29	115.7	8.98	48.5
13T	4.31	116.3	9.03	48.8
12T	4.33	117.0	9.08	49.0
11T	4.36	117.8	9.15	49.4
13T	4.38	118.4	9.19	49.6
12T	4.42	119.3	9.26	50.0
11T	4.45	120.3	9.34	50.4
13T	4.46	120.5	9.35	50.5
12T	4.50	121.5	9.43	50.9
13T	4.54	122.5	9.51	51.4
11T	4.55	122.7	9.53	51.4
12T	4.58	123.7	9.61	51.9
10T	4.60	124.2	9.64	52.1
13T	4.62	124.6	9.67	52.2
11T	4.64	125.2	9.72	52.5
12T	4.67	126.0	9.78	52.8
10T	4.70	126.9	9.85	53.2
11T	4.73	127.6	9.91	53.5
12T	4.75	128.3	9.96	53.8
10T	4.80	129.6	10.06	54.3
11T	4.82	130.1	10.10	54.5
12T	4.83	130.5	10.13	54.7
10T	4.90	132.3	10.27	55.5
11T	4.91	132.5	10.29	55.6
12T	4.92	132.8	10.31	55.6
10T	5.00	135.0	10.48	56.6
11T	5.00	135.0	10.48	56.6
12T	5.00	135.0	10.48	56.6
11T	5.09	137.5	10.67	57.6
10T	5.10	137.7	10.69	57.7
11T	5.18	139.9	10.86	58.6
10T	5.20	140.4	10.90	58.9
11T	5.27	142.4	11.05	59.7
10T	5.30	143.1	11.11	60.0
11T	5.36	144.8	11.24	60.7
10T	5.40	145.8	11.32	61.1
11T	5.45	147.3	11.43	61.7
10T	5.50	148.5	11.53	62.3
10T	5.60	151.2	11.74	63.4
10T	5.70	153.9	11.95	64.5
10T	5.80	156.6	12.16	65.6
10T	5.90	159.3	12.37	66.8
10T	6.00	162.0	12.58	67.9