Focused Drivetrain Tool

Gear Inches Calculator

Gear inches represents gearing as the diameter (in inches) of an equivalent direct-drive penny-farthing wheel.

Formula & Mechanics

Gear Inches = Wheel Diameter (Inches) × (Chainring / Sprocket)

Effective Wheel Diameter × Gear Ratio

1. Drivetrain Setup

Chainrings & Cassette

Chainrings (Teeth)

Cassette Sprockets (Teeth)

2. Wheel & Tire Model

Dimensions & Rollout

Select Preset Tire Size

Calculated wheel dimensions are theoretical estimates. Actual rollout varies with tire pressure, rim inner width, and rider weight. Use measured rollout for highest accuracy.

Gear Matrix

Chainrings (rows) vs Sprockets (columns). Color scale indicates range from lowest to highest.

Chainring \ Rear Cog	11T	12T	13T	14T	15T	17T	19T	21T	24T	28T	32T	34T
50T	121.3"	111.2"	102.7"	95.3"	89.0"	78.5"	70.2"	63.6"	55.6"	47.7"	41.7"	39.3"
34T	82.5"	75.6"	69.8"	64.8"	60.5"	53.4"	47.8"	43.2"	37.8"	32.4"	28.4"	26.7"

Range scale:Lowest→Mid→Highest

Orange dot = Duplicate or Near-duplicate gear ratio

Gear Table

Comprehensive sorted breakdown for every chainring x cassette sprocket combination

24 Total Gear Combinations

Gear	Combination	Ratio	Gear Inches	Development	Gain Ratio	Jump %	Speed (@90rpm)	Status
1	34T × 34T	1.00 : 1	26.7"	2.14 m	1.97	-	11.5 km/h (7.2 mph)	Unique
2	34T × 32T	1.06 : 1	28.4"	2.27 m	2.09	+6.3%	12.3 km/h (7.6 mph)	Unique
3	34T × 28T	1.21 : 1	32.4"	2.59 m	2.39	+14.3%	14.0 km/h (8.7 mph)	Unique
4	34T × 24T	1.42 : 1	37.8"	3.03 m	2.78	+16.7%	16.3 km/h (10.2 mph)	Unique
5	50T × 34T	1.47 : 1	39.3"	3.14 m	2.89	+3.8%	17.0 km/h (10.5 mph)	Unique
6	50T × 32T	1.56 : 1	41.7"	3.34 m	3.07	+6.3%	18.0 km/h (11.2 mph)	Unique
7	34T × 21T	1.62 : 1	43.2"	3.46 m	3.18	+3.6%	18.7 km/h (11.6 mph)	Unique
8	50T × 28T	1.79 : 1	47.7"	3.81 m	3.51	+10.3%	20.6 km/h (12.8 mph)	Near (1%)
9	34T × 19T	1.79 : 1	47.8"	3.82 m	3.52	+0.2%	20.6 km/h (12.8 mph)	Near (1%)
10	34T × 17T	2.00 : 1	53.4"	4.27 m	3.93	+11.8%	23.1 km/h (14.3 mph)	Unique
11	50T × 24T	2.08 : 1	55.6"	4.45 m	4.09	+4.2%	24.0 km/h (14.9 mph)	Unique
12	34T × 15T	2.27 : 1	60.5"	4.84 m	4.45	+8.8%	26.1 km/h (16.2 mph)	Unique
13	50T × 21T	2.38 : 1	63.6"	5.09 m	4.68	+5.0%	27.5 km/h (17.1 mph)	Near (2%)
14	34T × 14T	2.43 : 1	64.8"	5.19 m	4.77	+2.0%	28.0 km/h (17.4 mph)	Near (2%)
15	34T × 13T	2.62 : 1	69.8"	5.59 m	5.14	+7.7%	30.2 km/h (18.7 mph)	Near (1%)
16	50T × 19T	2.63 : 1	70.2"	5.62 m	5.17	+0.6%	30.4 km/h (18.9 mph)	Near (1%)
17	34T × 12T	2.83 : 1	75.6"	6.05 m	5.57	+7.7%	32.7 km/h (20.3 mph)	Unique
18	50T × 17T	2.94 : 1	78.5"	6.28 m	5.78	+3.8%	33.9 km/h (21.1 mph)	Unique
19	34T × 11T	3.09 : 1	82.5"	6.60 m	6.07	+5.1%	35.7 km/h (22.2 mph)	Unique
20	50T × 15T	3.33 : 1	89.0"	7.12 m	6.55	+7.8%	38.4 km/h (23.9 mph)	Unique
21	50T × 14T	3.57 : 1	95.3"	7.63 m	7.02	+7.1%	41.2 km/h (25.6 mph)	Unique
22	50T × 13T	3.85 : 1	102.7"	8.22 m	7.56	+7.7%	44.4 km/h (27.6 mph)	Unique
23	50T × 12T	4.17 : 1	111.2"	8.90 m	8.19	+8.3%	48.1 km/h (29.9 mph)	Unique
24	50T × 11T	4.55 : 1	121.3"	9.71 m	8.93	+9.1%	52.4 km/h (32.6 mph)	Unique