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 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 rear chainline and overlocknut distance may often be increased by adding spacers, or 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 product 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 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 must be larger with 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 a flat sprocket and a sprocket dished outward.

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. Dished sprockets from SRAM and Shimano are offset by 3 mm. Dimensions given in the table below 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.

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. The letters C, D and E are used in the table to indicate these three variations.

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.

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 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. Use a locknut as a spacer, with a washer under it as needed to increase space further.

If you add equal thicknesses to both sides, the chainline is unaffected, since it's measured from the middle outward. Hubs whose OLD can be adjusted use conventional threaded axles, so you can increase the spacing by removing the locknuts and adding spacer washers. The width which can be added is limited by the need for the axle nut to engage enough threads on the axle and the thickness of the left dropout

Axle Re-Spacing/Re-Dishing

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. Once you have respaced the hub, you'll need to re-dish the wheel by adjusting the spokes.

If a hub requires wider spacing than your bicycle has, and a steel frame, you can usually respace the frame.

Also see our article about frame spacing.

Sprocket Dishing

As mentioned, most internal-gear hubs have 3-lug "dished" sprockets that can be installed either dished in, or out, providing a choice of two different chainlines. Flat sprockets also are available. Interference with the hub or frame may prevent use of a small sprocket and/or determine which dishing will work. A sprocket may install perfectly well on the hub, but the chain still can interfere, so check with a chain.

Sprocket-Spacing Washers

Older Sturmey-Archer internal-gear hubs have two 1/16" (1.6 mm) spacer washers next to the sprocket. These can be arranged in various ways, along with the dishing of the sprocket, to optimize chainline.