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Read this article in connection with the lead article on chainline. That article covers chainline measurement, and adjustment of the chainline at the crankset. This article covers the adjustment of chainline of an internal-gear hub.
This article also lists the overlocknut distance -- an important consideration: different hubs fit different frames.
The word "chainline" refers to how straight the chain runs between the front and rear sprockets. Ideally, both sprockets should be in the same plane, so that there is no sideward motion or stress to the chain. This constitutes "perfect chainline".
Older internal gear hubs
|40.5-42 mm||Older bikes with 110 spacing would be on the smaller end of this range
Newer bikes with 120 mm spacing normally use 42 mm. Many newer internal-gear hubs have spacing of 125 to 135 mm, and a large chainline. Internal-gear hubs with rotary shifting (cable pulley inside the right dropout) generally have a wide spacing and a narrower chainline.
|Singlespeed MTB||52 mm||Wider chainline need for chainstay clearance on MTBs.
This is close to the chainline of the outer ring of a typical MTB triple.
This chainline is generally used with an overlocknut distance of 135 mm, so the bicycle frame will clear the chain.
|Rohloff Speedhub||54 mm
(58 mm w/13 tooth)
|47.5 mm||White Industries ENO hubs use this chainline, which lines up with the middle position of a typical MTB triple.
It's also fairly close to the outer position of a typical "road" double.
Older internal-gear hubs generally have an overlocknut distance of 114 through 120 mm and a chainline around 43 mm -- but newer internal-gear hubs vary widely. Most, though not all, have a larger overlocknut distance. Respacing the frame (possible only with steel frames) and adjusting the front chainline are often necessary when upgrading from an older hub. The adjustment of rear chainline and overlocknut may be made entirely or in part at the hub: increased by adding spacers, and sometimes decreased by using a thinner spacer or locknut.
The table below provides information on most current and recently-discontinued internal-gear hubs. Please feel free to send in information on hubs which are not yet covered.
Shimano information on chainline is spotty. Data in the table is mostly from measurements. SRAM's data is scattered around in SRAM manuals, and easier to access on this page. The table provides information on discontinued Sturmey-Archer hubs from the 1980-2000 period. Sturmey-Archer provides convenient online access to chainline info on current hubs, so this is only linked in the table.
In the table, chainline of hubs sold with only one overlocknut distance is given directly. Chainline of hubs which are available with different spacings on the left is described differently, as 1/2 OLD minus the distance from the sprocket's centerline to the right locknut face. For example, if the OLD is 130 mm, and the sprocket teeth are 20 mm to the left of the right locknut face, the chainline is 65 mm minus 20 mm, or 45 mm. The same hub with a additional 5 mm spacer at the left, to achieve an OLD of 135 mm, would have a chainline of 67.5 mm minus 20 mm, or 47.5 mm. Often, OLD is increased by an external brake such as a Shimano Rollerbrake. Some hubs are available with different axle lengths. Three different numbers are given, when applicable, for a sprocket dished inward (I), a flat sprocket (F) and a sprocket dished outward (O).
Most internal-gear hubs use standard sprockets with a 1.370 inch hole and 3 lugs, held to the driver by a circlip. These sprockets may be either dished or flat. SRAM and Shimano dished sprockets are offset by 3 mm. Dimensions given in this table reflect that dimension. Sturmey-Archer sprockets are offset by 1/16 inch (about 1.5 mm), and so they allow a somewhat narrower adjustment range. With some hubs, there is a minimum sprocket size due to interference problems, or sprockets may only be used dished one way or the other. There is more about sprockets on the main page about internal-gear hubs.
|Chainline of Internal-Gear Hubs|
FW=Freewheel C=Coaster D=Drum R=Roller
|Model/Type||Add spacers left?||OLD|
(meaning of O, F, I)
M 34 x 6 P6
|Shimano Nexus 3-speed w/bellcrank||Yes||127-135 (different models), see chart||Yes||1/2 OLD
- 12 (O);
- 15 (F);
|FW, Coaster, Roller||Standard||36 (other?)|
|Shimano Nexus 4-speed (FW, Roller)||Yes||133 (can be less w/o Roller-brake)||Yes||1/2 OLD
- 29 (O);
- 26 (F);
|FW, Roller||Standard||36 (other?)|
|Shimano Nexus 4-speed (C)||Yes||120||Yes|| 42.0 (O);
|Shimano Nexus 7-speed (FW, Roller, Disk)||Yes||130 (less w/o brake)||Yes||1/2 OLD
- 18 (O);
- 21 (F);
|FW, Roller, Disk||Standard||36 (other?)|
|Shimano Nexus 7-speed (C)||Yes||127||Yes||1/2 OLD
- 18 (O);
- 21 (F);
|Coaster||Standard||36 (other?)||Shimano Nexus, Alfine 8-speed (FW, Roller, Disk)||Yes||127-135 (less w/o Roller-brake), see chart||Yes||1/2 OLD
- 18 (O);
- 21 (F);
|FW, Roller, Disk||Standard||36 (other?)|
|Shimano Nexus, Alfine 8-speed (C)||Yes||132.5||Yes||1/2 OLD
- 18 (O);
- 21 (F);
- 24 (I)
|Sachs 3 x 7 (ribbed body)||Yes||126||No||1/2 OLD - 20||FW||Shimano compatible 7-speed cassette, no 11T||36|
|Spectro 3 x 7 (3-diameter body)||Yes||135||No||1/2 OLD-22.5||FW||Shimano compatible 7-speed cassette, no 11T||36|
|DualDrive II||Yes||135||No||42||FW||Shimano-compatible 8 or 9-speed cassette||36, 28|
|DualDrive II||Yes||135||No||45||Disc||Shimano-compatible 8 or 9-speed cassette||36,32|
Singlespeed Fixed/free switchable
|Yes||120, 130||Yes||42.5 (I),
|T3 (FW)||Yes||118, 127||Yes||38 (I)
|T3 (C)||Yes||118, 127||Yes||38.5 (I)
|i-Motion 3 (FW)||Yes||130||Yes||40.5 (I)
|SRAM i-Motion 3 (Disk)||Yes||135||Yes||40.5 (I)
|i-Motion 3 (C)||Yes||130||Yes||40.5 (I)
|Coaster||Standard||28, 32, 36|
|P5 (FW)||Yes||122||No||43 (I, 18)
45.5 (F, 16)
49 (O, 16)
|FW, Coaster||Standard||28, 32, 36|
|P5 Cargo (C)||Yes||122||No||43 (I, 18)
|P5 Cargo (Drum)||Yes||126||No||45.5 (I, 18)
48.5 (F, 16)
|P5 Cargo (D)||Yes||125||No||44 (I)
|Spectro S7, Sachs Super 7 (FW)||Yes||130||No||48 (I, 19)
51 (F, 18)
|Spectro S7, Sachs Super 7 (D)||Yes||135||No||50.5 (I, 19)
53.5 (F, 18)
|G8, G9||Yes||135||No||49.0||All||Non-standard, 4 lugs||32,36|
|i-Motion 9||Yes||135||Yes||48.8||Coaster, Disk||Non-standard, 4 lugs||32, 36|
|Sachs Elan 12-speed||No||135||No||45||Coaster, FW||Non-standard, 6 lugs||36|
|Sturmey-Archer (w/Shimano 3mm dished sprockets)|
|Elite AT3 (D)||Yes||120 and up||Yes||40-49||Drum||Standard||36 (other?)|
|Sprinter Coaster||Yes||120 and up||Yes||40-49||Coaster||Standard||36 (other?)|
|SAB (D)||Yes||120 and up||Yes||39-48||Drum||Standard||36 (other?)|
|Elite AT5 (D)||Yes||120 and up||Yes||39-48||Drum||Standard||36 (other?)|
|X-RD5 (D)||Yes||130 and up||Yes||43-52||Drum||Standard||36 (other?)|
|Sprinter 7 Elite (D)||Yes||130 and up||Yes||37-46||Drum||Standard||36 (other?)|
|Yes||115 (w/o brake) and up||Yes||1/2 OLD - 26 (F)||Plain||Non-Standard, 3 lugs||36|
|Sturmey-Archer current hubs||
Overlocknut distance and chainline are given in the technical specifications linked at the bottom of the page for each hub,
here on the Sturmey-Archer Web site. Sprockets are standard except with the 8-speeds and the S3X fixed-gear hub. Spacers may be added at either side, as long as axle end nuts engage fully.
Chainline may be adjusted at the rear wheel by rearranging spacers on the rear axle, and with a steel frame, also by re-spacing the rear dropouts to allow use of a longer or shorter rear axle. Adjustable hubs use conventional threaded axles, so you can increase the OLD spacing by removing the locknuts and adding spacer washers.
If you add equal thicknesses to both sides, the chainline is unaffected, since it's measured from the middle outward.
If you add more spacers to one side, or move them from one side to the other, you can change the chainline, but this will disturb the alignment of a disc brake rotor.
The drawing below is of a SRAM S7 coaster-brake hub. The OLD dimension is 130mm. The dimensions C, D and E are for the chainline with an inward-dished, flat and outward-dished sprocket. It would be possible to add a spacer on the left side for a bicycle with dropouts spaced 135mm -- though that would already increase this hub's rather wide chainline. The width which can be added is smaller, the thicker the left dropout limited by the need for the axle nut to engage enough threads on the axle.
As the right hand side of this hub does not use a locknut outside the bearing cone, adding a spacer on the right side is not a good idea. The bearing cone has serrations to bear against the dropout, and adding a spacer risks slippage.
Spacers, if any, are located just behind the outer locknuts, between the locknuts and the cones. You will need cone wrenches and a general understanding of hub bearing adjustment to do this job. Spacers can be added at the left end of the axle of most internal-gear hubs; sometimes, also at the right end.
It is almost always possible to add spacer washers on the left side of an internal-gear hub, or in many cases, to remove a washer or use a thinner locknut. Almost all internal-gear hubs are designed so bearings are adjusted only on the left, and many have the driver, or a a rotary shifting mechanism, immediately inside the right dropout. In this case, attempting to adjust or remove parts on the right may result in difficult reassembly or damage. It may be possible to add a spacer on the right, if there is still enough axle extension to hold the right-side axle nut -- and any shifter parts which are outside the dropout. Then use a locknut as a spacer, with a washer under it as needed to increase space further.
Once you have respaced the hub, you'll need to re-dish the wheel by adjusting the spokes.
Also see my article about frame spacing.
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