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Read this article in connection with the lead article on chainline, It covers chainline measurement, and adjustment of the front chainline (at the crankset). This article covers the adjustment of the rear chainline of a fixed sprocket or single-speed freewheel.
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". This article covers issues specific to bicycles without derailers.
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 135 mm, and a large 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
|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.
I have measured a selection of track sprockets, single freewheels and hubs with respect to chainline (units are millimeters.) The "Chainline" column is the distance from the mounting shoulder to the centerline of the sprocket teeth.
To figure the actual chainline for a given combination, add the number from the "chainline" column of the sprocket or freewheel to the corresponding "chainline" column of the hub chosen.
|Fixed (Track) Sprockets|
|Measured width||Total thickness||Thread Thickness|
|Miche Quick Change Splined||3/32"||5.85/5.15||1.9||7.72||7.3|
|Miche Quick Change Splined||1/8"||5.85/5.15||3.0||7.72||7.3|
|Sun Tour Superbe||3/32"||6.22||2.26||7.35||7.35|
|Sun Tour Superbe||1/8"||6.93||3.05||8.46||7.5|
|Surly New (2005)||3/32||6.4||2.0||7.4||7.4|
|Surly New (2005)||1/8"||5.9||3||7.4||7.4|
|Single-Speed and Fixed-Gear Hubs|
Center to Shoulder
|Left Side||Right Side||Drillings|
|Ambrosio large flange||Track||120||?||36||Fixed||Fixed||32|
|Campagnolo small flange 2002||Track||120||Yes||36||Plain||Fixed||28, 32, 36|
|Campagnolo C-Record Large flange||Track||120||Yes||35.9||Plain||Fixed||28, 32, 36|
|Gold Tec||Track||120, 130, 135||Yes||39.5||Fixed||Fixed||32, 36|
|Miche||Track||120||Yes||36.3||Plain||Fixed||28, 32, 36|
|On-One Full Monty||MTB||135||No||43.3||Plain||Free||32, 36|
|Phil Wood Track||Track||120, 126, 130||No||36.75||Plain|
|Fixed||28, 32, 36|
|Phil Wood K.I.S.S. Off||MTB||135||No||45.35||Plain/Free||Fixed/Free||32, 36|
|Shimano Dura-Ace 7700||Track||120||Yes||35.3||Fixed||28, 32, 36|
|Shimano Dura-Ace 7700 Small Flange||Track||120||Yes||35.3||Fixed||28, 32, 36|
|Shimano Dura-Ace 7600 Large Flange||Track||120||Yes||35.4||Fixed||28, 32, 36|
|Spot||MTB||135||No||47.25||Plain||Free||28, 32, 36|
|Track/MTB||120, 130||Yes||See in IG Hub list||Plain||Fixed/Free|
|Surly 1 x 1||MTB||135||Yes||46.5||Free||Fixed/Free||Drillings|
|Suzue Basic||Track||117-120||Yes||34.74||Free||Fixed||28, 32, 36|
|Suzue Promax (cartridge)||Track||120||Yes||35.0||Free||Fixed||28, 32, 36|
|Suzue Promax NJS||Track||120||Yes||35.0||Fixed||Fixed||28, 32, 36|
|White Industries ENO||Track/MTB||126, 130, 135||No||39.1||Free||Fixed||28, 32, 36|
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 render a double-sided hub unusable on one side or the other, since you'll be increasing the chainline on one side while decreasing it on the other -- unless you also use a double chainring in front. Moving spacers from one side to the other also will disturb the alignment of a disc brake.
The spacers are located just behind the outer locknuts, between the locknuts and the cones (or the bearing mounting nuts, if your hub uses cartridge bearings.) You will need cone wrenches and a general understanding of hub bearing adjustment to do this job.
Assuming the rear hub's spacing already matches your frame's spacing, you can take spacer washers from one side of the hub and move them to the other side, thus shifting the entire hub from side to side. In the case of a hub originally meant for a multi-speed freewheel, there is usually a rather thick spacer on the right (freewheel) side of the hub. You can replace this with a stack of thinner spacer washers that add up to the same overall thickness, then distribute the washers from side to side as needed to get the chainline where you need it to be.
Once you have done this, you'll need to re-dish the wheel by adjusting the spokes. This is a bit of trouble, but, in the case of multi-to-single-speed conversion, the re-dishing actually results in making the wheel much stronger than it was.
Also see my article about frame spacing.
Fixed-gear sprockets are usually intended to be installed with the flange facing inward, so the teeth are outboard. However, in many cases, it is possible to flip a fixed-gear sprocket over if you need to move the rear chainline to the left.
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