Chainline and gearing

Chainline

With a splined sprocket the SPEEDHUB runs on a 57 mm chainline (the old threaded sprocket: 54 mm). On a triple crankset the middle ring sits at about 47.5 mm from the frame centre and the large ring at just the 57 mm needed. So on most touring and mountain bikes the cranks and bottom bracket can stay when converting: you use the large (outer) ring and remove the others. Five chainring spacers come with the conversion — they go in place of the middle ring, so the chainring bolts need no replacing or shortening (5 mm Allen, 7 Nm, lightly greased).

The exact chainline depends on the carrier and dropout width — see the table in Sprocket: turning, replacing, splined.

Chain angle

With a chainstay of about 450 mm, 0.5° of chain angle means about 4 mm of offset, 1° about 8 mm — technically not critical, but the straighter the chain, the better the efficiency and the longer it lasts. For comparison: on a 12–13-speed derailleur, the chain runs at 5–6°, with 40–45 mm of offset.

Internal ratios

Gear	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Ratio	0.279	0.316	0.360	0.409	0.464	0.528	0.600	0.682	0.774	0.881	1.000	1.135	1.292	1.467

The minimum permitted ratio

The ratio of chainring to sprocket teeth (the primary ratio) must not be too small, or the gearbox takes too much torque:

Use	Minimum ratio (chainring : sprocket)
solo rider up to 100 kg	1.9
tandem or rider over 100 kg	2.5
13 or 14-tooth splined sprocket — in every case	3.0

In practice, a ratio of 2.5–2.8 has proved itself for touring and everyday riding.

E-bikes with a mid-motor

The SPEEDHUB’s input torque may be at most 130 Nm — the sum of rider and motor torque, divided by the primary ratio.

Vehicle	Minimum ratio	Max. torque at gearbox shaft	Up to 250 W / 800 W	Above	Max. system weight	Max. wheel load
solo bike, max. 100 kg rider	1.9	250 Nm	✓	✓	250 kg	150 kg
tandem, over 100 kg	2.5	325 Nm	✓	—	250 kg	150 kg
cargo/recumbent, SPEEDHUB in the driven wheel	2.5	325 Nm	✓	—	250 kg	150 kg
same, over 250 kg	3.0	390 Nm	✓	—	over 250 kg	150 kg
cargo/recumbent, SPEEDHUB as intermediate gearbox	2.5	325 Nm	✓	—	250 kg	—
same, over 250 kg	3.0	390 Nm	✓	—	over 250 kg	—

Example: rider 150 Nm, motor 100 Nm, ratio 2.5 → (150 + 100) : 2.5 = 100 Nm — OK. With a rider at 250 Nm: (250 + 100) : 2.5 = 140 Nm — too much.

Work it out

A gear’s development — how many metres the bike travels per crank turn:

development = wheel circumference × chainring ÷ sprocket × internal ratio

The internal ratio comes from the table above. On a derailleur it is the same without the internal ratio: circumference × chainring ÷ sprocket. That way any SPEEDHUB combination can be compared with any derailleur gear.

Compared with a derailleur

If you are coming from a derailleur, this table shows what the SPEEDHUB’s lowest and highest gears match: gear 1 is compared with a 22-tooth small chainring, gear 14 with an 11-tooth smallest sprocket.

Chainring / sprocket	Gear 1 ≈ on a derailleur	Gear 14 ≈ on a derailleur
38/15	22/31	41/11
38/16	22/33	38/11
38/17	22/35	36/11
40/15	22/30	43/11
40/16	22/32	40/11
40/17	22/34	38/11
42/15	22/28	45/11
42/16	22/30	42/11
42/17	22/32	40/11
44/15	22/27	47/11
44/16	22/29	44/11
44/17	22/30	42/11
46/15	22/26	49/11
46/16	22/27	46/11
46/17	22/29	44/11
48/15	22/25	52/11
48/16	22/26	48/11
48/17	22/28	46/11
50/15	22/24	54/11
50/16	22/25	50/11
50/17	22/27	47/11
52/15	22/23	56/11
52/16	22/24	52/11
52/17	22/26	49/11

Development tables

The tables show how many metres the bike travels per crank turn in gear 1 and gear 14. Rows: chainring, columns: sprocket. Bold values are the smallest permitted combinations for tandems, riders over 100 kg and the 13–14-tooth sprockets.

20” wheel (circumference 1.51 m)

Chainring \ sprocket	13 T	14 T	15 T	16 T	17 T	18 T	19 T	21 T
28 T			0.79 – 4.13
30 T			0.84 – 4.43	0.79 – 4.15
32 T			0.90 – 4.73	0.84 – 4.43	0.79 – 4.17
34 T			0.95 – 5.02	0.90 – 4.71	0.84 – 4.43	0.80 – 4.18
36 T			1.01 – 5.32	0.95 – 4.98	0.89 – 4.69	0.84 – 4.43	0.80 – 4.20
38 T			1.07 – 5.61	1.00 – 5.26	0.94 – 4.95	0.89 – 4.68	0.84 – 4.43
40 T	1.30 – 6.82		1.12 – 5.91	1.05 – 5.54	0.99 – 5.21	0.94 – 4.92	0.89 – 4.66	0.80 – 4.22
42 T	1.36 – 7.16	1.26 – 6.65	1.18 – 6.20	1.11 – 5.81	1.04 – 5.47	0.98 – 5.17	0.93 – 4.90	0.84 – 4.43
44 T	1.43 – 7.50	1.32 – 6.96	1.24 – 6.50	1.16 – 6.09	1.09 – 5.73	1.03 – 5.41	0.98 – 5.13	0.88 – 4.64
46 T	1.49 – 7.84	1.38 – 7.28	1.29 – 6.79	1.21 – 6.37	1.14 – 5.99	1.08 – 5.66	1.02 – 5.36	0.92 – 4.85
48 T	1.56 – 8.18	1.44 – 7.59	1.35 – 7.09	1.26 – 6.65	1.19 – 6.25	1.12 – 5.91	1.06 – 5.60	0.96 – 5.06
50 T	1.62 – 8.52	1.50 – 7.91	1.40 – 7.38	1.32 – 6.92	1.24 – 6.52	1.17 – 6.15	1.11 – 5.83	1.00 – 5.27
52 T	1.69 – 8.86	1.56 – 8.23	1.46 – 7.68	1.37 – 7.20	1.29 – 6.78	1.22 – 6.40	1.15 – 6.06	1.04 – 5.49
54 T	1.75 – 9.20	1.62 – 8.54	1.52 – 7.97	1.42 – 7.48	1.34 – 7.04	1.26 – 6.65	1.20 – 6.30	1.08 – 5.70
56 T	1.81 – 9.54	1.69 – 8.86	1.57 – 8.27	1.47 – 7.75	1.39 – 7.30	1.31 – 6.89	1.24 – 6.53	1.12 – 5.91

26” wheel (circumference 2.06 m)

Chainring \ sprocket	13 T	14 T	15 T	16 T	17 T	18 T	19 T	21 T
28 T			1.07 – 5.64
30 T			1.15 – 6.04	1.08 – 5.67
32 T			1.23 – 6.45	1.15 – 6.04	1.08 – 5.69
34 T			1.30 – 6.85	1.22 – 6.42	1.15 – 6.04	1.09 – 5.71
36 T			1.38 – 7.25	1.29 – 6.80	1.22 – 6.40	1.15 – 6.04	1.09 – 5.73
38 T			1.46 – 7.66	1.37 – 7.18	1.28 – 6.76	1.21 – 6.38	1.15 – 6.04
40 T	1.77 – 9.30		1.53 – 8.06	1.44 – 7.56	1.35 – 7.11	1.28 – 6.72	1.21 – 6.36	1.09 – 5.76
42 T	1.86 – 9.76	1.72 – 9.07	1.61 – 8.46	1.51 – 7.93	1.42 – 7.47	1.34 – 7.05	1.27 – 6.68	1.15 – 6.04
44 T	1.95 – 10.23	1.81 – 9.50	1.69 – 8.86	1.58 – 8.31	1.49 – 7.82	1.40 – 7.39	1.33 – 7.00	1.20 – 6.33
46 T	2.03 – 10.69	1.89 – 9.93	1.76 – 9.27	1.65 – 8.69	1.56 – 8.18	1.47 – 7.72	1.39 – 7.32	1.26 – 6.62
48 T	2.12 – 11.16	1.97 – 10.36	1.84 – 9.67	1.72 – 9.07	1.62 – 8.53	1.53 – 8.06	1.45 – 7.63	1.31 – 6.91

650B wheel (circumference 2.15 m)

Chainring \ sprocket	13 T	14 T	15 T	16 T	17 T	18 T	19 T	21 T
28 T			1.12 – 5.89
30 T			1.20 – 6.31	1.12 – 5.91
32 T			1.28 – 6.73	1.20 – 6.31	1.13 – 5.94
34 T			1.36 – 7.15	1.27 – 6.70	1.20 – 6.31	1.13 – 5.96
36 T			1.44 – 7.57	1.35 – 7.10	1.27 – 6.68	1.20 – 6.31	1.14 – 5.98
38 T			1.52 – 7.99	1.42 – 7.49	1.34 – 7.05	1.27 – 6.66	1.20 – 6.31
40 T	1.85 – 9.70		1.60 – 8.41	1.50 – 7.89	1.41 – 7.42	1.33 – 7.01	1.26 – 6.64	1.14 – 6.01
42 T	1.94 – 10.19	1.80 – 9.46	1.68 – 8.83	1.57 – 8.28	1.48 – 7.79	1.40 – 7.36	1.33 – 6.97	1.20 – 6.31
44 T	2.03 – 10.68	1.89 – 9.91	1.76 – 9.25	1.65 – 8.67	1.55 – 8.16	1.47 – 7.71	1.39 – 7.30	1.26 – 6.61
46 T	2.12 – 11.16	1.97 – 10.36	1.84 – 9.67	1.72 – 9.07	1.62 – 8.53	1.53 – 8.06	1.45 – 7.64	1.31 – 6.91
48 T	2.21 – 11.65	2.06 – 10.81	1.92 – 10.09	1.80 – 9.46	1.69 – 8.91	1.60 – 8.41	1.52 – 7.97	1.37 – 7.21

28” wheel (circumference 2.18 m)

Chainring \ sprocket	13 T	14 T	15 T	16 T	17 T	18 T	19 T	21 T
28 T			1.14 – 5.97
30 T			1.22 – 6.40	1.14 – 6.00
32 T			1.30 – 6.82	1.22 – 6.40	1.14 – 6.02
34 T			1.38 – 7.25	1.29 – 6.80	1.22 – 6.40	1.15 – 6.04
36 T			1.46 – 7.68	1.37 – 7.20	1.29 – 6.77	1.22 – 6.40	1.15 – 6.06
38 T			1.54 – 8.10	1.44 – 7.60	1.36 – 7.15	1.28 – 6.75	1.22 – 6.40
40 T	1.87 – 9.84		1.62 – 8.53	1.52 – 8.00	1.43 – 7.52	1.35 – 7.11	1.28 – 6.73	1.16 – 6.09
42 T	1.97 – 10.33	1.82 – 9.59	1.70 – 8.95	1.60 – 8.39	1.50 – 7.90	1.42 – 7.46	1.34 – 7.07	1.22 – 6.40
44 T	2.06 – 10.82	1.91 – 10.05	1.78 – 9.38	1.67 – 8.79	1.57 – 8.28	1.49 – 7.82	1.41 – 7.41	1.27 – 6.70
46 T	2.15 – 11.32	2.00 – 10.51	1.87 – 9.81	1.75 – 9.19	1.65 – 8.65	1.55 – 8.17	1.47 – 7.74	1.33 – 7.01
48 T	2.25 – 11.81	2.09 – 10.96	1.95 – 10.23	1.82 – 9.59	1.72 – 9.03	1.62 – 8.53	1.54 – 8.08	1.39 – 7.31
50 T	2.34 – 12.30	2.17 – 11.42	2.03 – 10.66	1.90 – 9.99	1.79 – 9.41	1.69 – 8.88	1.60 – 8.42	1.45 – 7.61

29” wheel (circumference 2.30 m)

Chainring \ sprocket	13 T	14 T	15 T	16 T	17 T	18 T	19 T	21 T
28 T			1.20 – 6.30
30 T			1.28 – 6.75	1.20 – 6.33
32 T			1.37 – 7.20	1.28 – 6.75	1.21 – 6.35
34 T			1.45 – 7.65	1.36 – 7.17	1.28 – 6.75	1.21 – 6.37
36 T			1.54 – 8.10	1.44 – 7.59	1.36 – 7.15	1.28 – 6.75	1.22 – 6.39
38 T			1.63 – 8.55	1.52 – 8.01	1.43 – 7.54	1.35 – 7.12	1.28 – 6.75
40 T	1.97 – 10.38		1.71 – 9.00	1.60 – 8.44	1.51 – 7.94	1.43 – 7.50	1.35 – 7.10	1.22 – 6.43
42 T	2.07 – 10.90	1.93 – 10.12	1.80 – 9.45	1.68 – 8.86	1.59 – 8.34	1.50 – 7.87	1.42 – 7.46	1.28 – 6.75
44 T	2.17 – 11.42	2.02 – 10.60	1.88 – 9.90	1.76 – 9.28	1.66 – 8.73	1.57 – 8.25	1.49 – 7.81	1.34 – 7.07

26” Fatbike wheel (circumference 2.32 m)

Chainring \ sprocket	13 T	14 T	15 T	16 T	17 T	18 T	19 T	21 T
28 T			1.21 – 6.35
30 T			1.29 – 6.81	1.21 – 6.38
32 T			1.38 – 7.26	1.29 – 6.81	1.22 – 6.41
34 T			1.47 – 7.71	1.38 – 7.23	1.29 – 6.81	1.22 – 6.43
36 T			1.55 – 8.17	1.46 – 7.66	1.37 – 7.21	1.29 – 6.81	1.23 – 6.45
38 T			1.64 – 8.62	1.54 – 8.08	1.45 – 7.61	1.37 – 7.19	1.29 – 6.81
40 T	1.99 – 10.47		1.73 – 9.08	1.62 – 8.51	1.52 – 8.01	1.44 – 7.56	1.36 – 7.17	1.23 – 6.48
42 T	2.09 – 11.00	1.94 – 10.21	1.81 – 9.53	1.70 – 8.93	1.60 – 8.41	1.51 – 7.94	1.43 – 7.52	1.29 – 6.81
44 T	2.19 – 11.52	2.03 – 10.70	1.90 – 9.98	1.78 – 9.36	1.68 – 8.81	1.58 – 8.32	1.50 – 7.88	1.36 – 7.13
46 T	2.29 – 12.04	2.13 – 11.18	1.98 – 10.44	1.86 – 9.78	1.75 – 9.21	1.65 – 8.70	1.57 – 8.24	1.42 – 7.46
48 T	2.39 – 12.57	2.22 – 11.67	2.07 – 10.89	1.94 – 10.21	1.83 – 9.61	1.73 – 9.08	1.64 – 8.60	1.48 – 7.78