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John Forester has kindly granted permission to republish his information about Sturmey-Archer 4- and 5-speed hubs here. We cover these hubs and are pleased to add Forester's detailed advice. He dips back into history of these hubs and describes several clever modifications which apply to many hubs. His technical description is refined and precise, a model for other writers.
The hubs which Forester describes are no longer manufactured, and information on current internal-gear hubs is available through the manufacturers. The material in this article was published in the 5th (1984) edition of his book Effective Cycling, but was later dropped.
The current edition of Effective Cycling is available in hardcover, paperback or Kindle digital format.
There is a page on this site linking to Sturmey-Archer's technical information on its 5-speed hubs, old and new. -- John Allen]
Hub gears are now returning to their rightful place in the cycling world. When I was young many club cyclists used Sturmey-Archer hub gears, which were then available in four 3-speed types and three 4-speed types. Derailleurs were not as good then as today, and many cyclists preferred the Sturmey-Archer's instantaneous shifting, general reliability, and weather resistance. Some had several rear wheels with different hubs and a stock of different sprockets to select for different riding conditions. But as derailleurs improved and became cheaper, the more expensive close-ratio Sturmeys used by club cyclists disappeared from the marketplace. So far as most people were concerned, only the cheap and lowly AW wide-ratio 3-speed remained; it was used on roadster bicycles by people who didn't want to get involved with the derailleur's complications. With ratios of 1.33, 1.00, and 0.75 (giving gears of 100, 75, and 56, for example, or, with a different sprocket or chainwheel, of 88, 66, and 49), it enabled weak cyclists to climb quite reasonable hills slowly, but the gears were so far apart that the club cyclist was spun out in one gear but found that the next higher gear was too high for efficient cycling.
What few Americans realized was that Sturmey-Archer's FW wide-ratio 4-speed remained in production and was interchangeable with the AW, even to the shell and the shift trigger. If you were lucky to find a 4-speed hub it probably had a 40-spoke shell, but you could slip its mechanism into a 3-speed 36-hole shell, and the standard trigger had four ratchet teeth and was marked "3 or 4 speed." It had ratios of 1.27, 1.00, 0.79, and 0.67, giving gears, for example, of 88, 69, 55, and 46. This was quite reasonable for a cyclist's utility bike, and I prized an FW that had been made in 1968. I fitted it, inside a 36-hole shell, into a Raleigh frame and built up a beginning clubman's bicycle in the style of the 1940s, similar to the Raleigh Lenton Sports but with modem rims and tires. I used it for conferences, rain riding, pulling a freight trailer, and other tasks involving utility cycling or travel by airplane or rail.
Now I knew that the 4-speed hub actually had two different 3-speeds inside it, which would give five different gears, but it used only the three gears of the narrow-ratio set and the decrease gear of the wide-ratio set. The unused increase gear could be reached by some machining modifications that allowed a second cable to be installed from the left end, as MIT engineering students had shown me in 1949.
Sturmey-Archer now makes the S-5.2 5-speed hub. This has more advantages over the 4-speed than just the additional gear. The 4-speed often shifted slowly from third gear to fourth gear, sometimes jumping out of gear if you drove hard before it had completed the shift. The mechanism for selecting low gear was delicate and easily damaged. The 5-speed makes all shifts smartly, and the selection mechanisms are as robust as those of the 3-speed. The price you pay for this is a strong left spring, which requires a stronger pull on the left trigger than on the right. In a return to the finer practices of earlier days, S-A now offers the S-5.2 with a light-alloy shell, which saves 80 grams and, more important, provides thicker flanges that ought to reduce the frequency of spoke breakage. I have used a 5-speed on a utility bicycle for rain riding, for hauling a freight trailer, for trips that would have jeopardized a derailleur by involving much handling of the bicycle as baggage, and for similar uses, with complete success.
The ratios of the S-5.2 are 1.50, 1.27, 1.00, 0.79, and 0.67, which, geared for an 88 top, give gears of 88, 74, 59, 46, and 39. That is a set of gears that a cyclist can be happy with for quite a variety of rides. It covers a sufficiently wide range to take care of most conditions, yet the jumps between gears are no worse than some of those on nominal 10-speeds with cross-over gearing. This set of gears is sufficiently useful that the cycling enthusiast can benefit from the advantages of hub gears in particular services. In traffic, hub gears make fast changes for the many stops and starts and speed changes, even when you suddenly have to change your plans to suit the traffic situation. In rainy-weather cycling, when your cape prevents you from seeing derailleurs and the sounds of splashes and car tires on wet pavement obscure their sounds, hub gears give sure and certain shifts. In muddy or snowy conditions, hub gears are much less likely to suffer damage from foreign objects or materials. When your bicycle must be handled by airline or railroad personnel, hub gears are less likely than derailleurs to be damaged. (Unscrew the shift chains and put them in your tool kit so they won't be damaged.) For small-wheeled bicycles (such as folders) and for Rann trailers for children (described in chapter 41), the top gear increase of 1.5 gives reasonable gears with normal chainwheels and sprockets. And, of course, you can slip a fixed-gear wheel into the same frame and chain to get some fixed-gear training.
However, to get these advantages you have to make some changes, for Sturmey-Archer didn't have enthusiastic cyclists in mind when marketing the S-5.2. The 5-speed requires two shift triggers, so S-A produced two large stem-mounted levers. All stem-mounted levers are dangerous in a crash. Fortunately, the S-5.2 can be shifted with two standard Sturmey-Archer 3-speed handlebar triggers, one trigger on each side. For dropped handlebars, mount the triggers just above the brake levers, down and to the inside, so that when you are on the drops you shift with your thumbs. When you are on the tops, you shift with fingers or thumbs. Sturmey-Archer makes two different clamping bolts for triggers. The shorter is for 7/8" bars, the longer for 15/16" bars. Run the cables along the top tube and down each seat stay, using either the cable housing and stops provided or the standard 3-speed cable stops and pulleys. I use cable-housing stops at the front of the top tube and cable pulleys just in front of the seat lug, all brazed on, with bare cable between, because that was the best practice when Sturmeys were common.
Sturmey-Archer used to make quick-release fittings, so that when removing the wheel you could quickly disconnect the shift chain from the shift cable without losing the adjustment, but they haven't brought these back. So you make your own. Before adjusting each shift cable, put a lockwasher and another shift-chain locknut onto the shift-chain shank. Then when the adjustment is correct (see below) run the top locknut against the adjusting thimble, and run the lower nut tightly against the upper, with the lockwasher between. That way, the two nuts are more tightly jammed together than they are to the thimble, so they retain the adjustment when you unscrew the thimble in order to remove the wheel.
The modern trigger has a plastic knob on the end that makes shifting more difficult when it is mounted on dropped bars. Required by the Consumer Product Safety Commission, this is intended to prevent it from stabbing you. In view of where you will be installing it, this is no danger at all. If you like, disassemble the trigger, and (with a torch and a hammer) burn off the plastic knob and forge the metal shank into a comfortably curved trigger just like the old ones. To disassemble the trigger, remove the mounting screw and the cover plate. You won't need the cover plate; it is marked I, II, and III, which won't do you any good with a 5-speed. You will see three pins that hold the assembly together. With a pin punch applied to the small end of the center pin, drive out the center pin and pull out the trigger and the ratchet plate. Reforge the trigger and reinstall the trigger and the ratchet plate. Remember to hold the pawl away from the ratchet plate in order to insert the plate and trigger properly. Reinstall the pin. Because you are discarding the cover plate that retains the pins, secure the large end of each pin to the main frame with a drop of epoxy glue. Because you will be using only the two looser positions of the left trigger, it is wise to install a stop. Pull on the cable and set the trigger to the central position. You don't want to tighten the cable any further, so install a stop that prevents the trigger from moving any further. With a hacksaw or a thin file cut notches in the trigger-frame side plates just beyond the trigger position. Into them install a piece of broken spoke with epoxy glue. This will prevent the trigger from moving too far if you forget and pull when it is already at the central position.
When installing a Sturmey-Archer hub, you must prevent the axle from turning. To see why this is so, consider the hub as a torque-changing device as well as a speed-changing device. When you are in decrease gears, the hub twists the wheel with more torque than you are applying through the drive sprocket. The extra forward torque comes from the bicycle's frame, and is developed as the axle tries to turn backwards in the dropouts. Contrariwise, when you are in increase gears, the wheel uses less torque than you are applying, and the balancing backward torque again comes from the bicycle's frame as the axle tries to twist forward in the dropouts. So unless you are careful the reversing torques as you go from increase gears to decrease gears and back again will loosen the axle in the dropouts. Sturmey-Archer axles have two flats, and the dropouts for bicycles designed for Sturmey hubs have narrow slots that just accept the axle. Also, Sturmey-Archer supplies two sizes of special anti-rotation washers that fit over the axle and have tabs that fit into the dropout slot. Always use the washers. If you have a frame with standard dropouts, get the special antirotation washers with the tabs sized for standard slots.
Five-speed hubs come with a choice of three axle lengths: 149 mm, 155 mm, and 162 mm. The hub, which itself is 114 mm wide, can be packed out with spacing washers to the width between your dropouts. In order to accept the anti-rotation washers and the axle nuts, the axle must be at least 22 mm longer than the outside width of the dropouts. If the axle is too long, install spacing washers between the anti-rotation washer and the nut, so that when the nuts are tightened the ends of the axle show in the windows that are cut into the nuts.
Each length of axle has its own lengths of gear-indicator spindles, to which shift chains are permanently attached. If you change axle lengths, also buy the appropriate gear indicators and shift chains. It is wise to buy an extra pair for spares in case of damage. Also, because the most frequent damage is to the shift chains (from falling down),
use the plastic protectors that fit over the axle ends. They will save you grief.
Fig 15.1 Adjustment of Sturmey-Archer hub gear. On a 3-speed this is the middle gear. On a 5-speed this is third gear on the right side (middle position) and the narrow range on the left side (taut wire position).
To adjust the shifting mechanism (figure 15.1), first install the indicator spindles and the shift chains. There are three lengths of indicator spindles. The medium-length axle, 155 mm, has medium-length spindles on both sides. The short axle, 149 mm, has a medium and a short spindle, with the shorter on the right. The long axle, 162 mm, has a medium and a long spindle, with the shorter on the right. Remember, if the correct spindles are of different lengths, the shorter always goes on the right. Screw each in as far as it will go, back it off less than half a turn, and connect each to the shift cable. Roughly adjust the shift cable's length at the cable clamp bolt. Finely adjust it by turning the connecting thimble onto the chain shank. Whenever tightening a cable, turn the cranks slowly so the mechanism can move to its shiftable position. For the right side, set the trigger to the central position, and adjust the cable so the shoulder near the end of the indicator spindle is flush with the axle end as seen through the axle-nut window. For the left side, set the trigger to the tighter position (the central position of the unmodified trigger) and adjust the cable so the spindle shoulder is flush with the axle end. Test by applying strong force to the pedals in each position of each trigger. There should be no jumping out of gear. If the hub ever jumps out of gear or gives any trouble, first inspect and readjust the shift cables. These are the most likely sources of trouble.
[This advice assumes that the correct indicator spindle is used. A shorter one also will work but must be adjusted differently, as described here -- John Allen]
Sooner or later you will temporarily remove the shift chains—for example, to prevent damage when loading the bike into a car or an airplane. Because each side is adjusted to a different length (even if the spindles are the same length), you ought to identify the left and right chains so you will be able to reinstall them correctly and won't have to readjust them. Any system that is familiar to you is satisfactory. I paint a band around each chain shank and adjusting thimble, red on the left and green on the right (same as lights on a ship).
The shift pattern is not hard to remember once you understand what is going on. The left trigger selects between the wide-range and narrow-range gear sets. Wide ratio is loose cable, narrow ratio is tight cable. The right trigger selects increase, direct, or decrease of whichever gear set is active. Decrease is tight, direct is central, and increase is loose, just as in the usual 3-speed. So for most riding you ride in the narrow range, left trigger tight, and use the right trigger to select gears 2, 3, and 4. If you climb a hill and find that gear 2 (narrow decrease) is not low enough, you loosen the left trigger into wide range decrease to get the lowest gear, 1. When the hill eases, you go to narrow-range decrease (gear 2) by tightening the left trigger. If under favorable riding conditions you find that gear 4 (narrow-range increase) is not high enough, you loosen the left trigger to go to wide-range increase (gear 5). If conditions worsen, you return to narrow-range increase (gear 4) by tightening the left trigger. In other words, you use the left trigger only for the extremes. To reach the extremes, gear 1 or gear 5, loosen the left trigger. To return from the extremes, to either gear 2 or gear 4, tighten the left trigger. Gear 3 is always direct, no matter which range is selected, so it makes sense to leave the left trigger alone for all shifts between gears 2, 3, and 4. You never need to move both triggers at once. See table 15.1.
Table 15.1 Shift Table for S5.2 5-Speed Hub
[With the early version, S5, which had a bellcrank at the left end of the axle, the operation of the left trigger was opposite -- John Allen].
Most troubles are external, involving the shift chains or their cables. Repair is largely self-evident. Connecting the cables to the triggers requires pulling the trigger all the way tight. Insert the cable end through the slotted hole and between the pawl and the ratchet plate, and pull it clear of the ratchet plate. Then let it fall back into the slot in the far end of the ratchet plate as you pull it backward.
Bearing adjustment requires three steps. First, loosen the left locknut and cone. Second, tighten the right cone finger tight. This pulls the mechanism all the way to the right, so the gears and the dogs all line up correctly. Make sure that the left cone is still loose. If it isn't, loosen it some more and retighten the right cone. This is very important. Then loosen the right cone a quarter turn, and loosen it further until the lock washer will just slip on. Tighten the locknut. The axle assembly should rotate freely inside the hub. If it doesn't, back off the cone not more than another quarter turn, and retighten the locknut. Then adjust the left cone in the normal way.
If you wish to disassemble a hub, first try to get the one-sheet S5/2 specification, which has an exploded drawing and a parts list. If you mix up the parts, it will make reassembly easier, and it will tell you the numbers of any parts you might require.
If you want to remove the complete hub from its wheel, start by loosening the right ball-bearing ring as instructed below. (This is important because it is much easier to hold the wheel than it is to hold the hub shell while loosening the ring, which may be quite tight.)
Remove the sprocket and the left cone (the one opposite the sprocket). Match-mark the right ball-bearing ring and the hub shell, so you will know if they go back together properly. Then, using the wheel to hold the hub shell, use a hammer and a drift against the notches in the right ball-bearing ring to unscrew it. It is a normal right-hand thread. (Sturmey-Archer makes a special wrench, and a shell holder for use if the hub is out of a wheel, but you won't have these tools.) When the right ball-bearing ring unscrews, all the insides come out as a unit (except for the left cone, locknut, and spacers, which you have already removed). Then, taking care to put the parts down on the workbench in the order in which they come out, unscrew the right cone and take as much apart as you need. You can replace any broken or worn parts.
If you have mechanical aptitude and study the parts as you take them apart, you will see how they go together again. There are only a few non-obvious points. The planet-cage pawls and the ring-gear pawls are different. Those on the ring gear have inner beveled faces so that they are retracted by the clutch cross as it moves all the way to the right. All pawl pins insert from the right end. The axle keys that the gear indicators screw into are different, and the key on the right has flatted ends that fit against its collar. There are two springs inside the sun gears; the longer and stronger is on the left so the sun gears rest to the right. And there is one very non-obvious point: When replacing the planet pinions you must install them in proper rotational position. Each planet pinion has one marked tooth. The mark is a line stamped into the end face of one tooth of the larger gear, at the end facing the smaller gear. Inspect each planet pinion and find the mark. Slip the planet cage over the axle assembly with its sun gears already installed. Insert each planet pinion so its marked tooth points exactly outward, and then insert its pin. Look at all three planet gears to see that all marked teeth simultaneously point exactly outwards. If one doesn't, extract its pin (a magnet is handy here) and reinstall it properly. When you think that all are correct, slip the ring gear over the planets and rotate it at least ten times. If the planets are properly "timed," the ring will rotate smoothly. If they aren't, it will go from looser to tighter every few revolutions.
When installing the right ball-bearing ring into the shell, notice that the ring has a two-start thread. If it starts properly, the match marks will line up again. If they don't line up when the shell is screwed home, unscrew it and try again from a different starting angle.
Sturmey-Archer prefers that you grease the bearings at the axle cones at assembly, because they are furthest from the internal oil. I use plenty of oil, and I have never found my bearings to be dry.
Adjust the cones as previously directed.
Oil the bearings thoroughly and let them drain before using the bicycle. Oil the hub frequently but lightly when in use. Oil the trigger and ratchet movements for easy operation.
Sturmey-Archer sprockets are easily changed to select the appropriate gear range and come with from 13 to 22 teeth.
[These are interchangeable with Shimano and SRAM sprockets; some are available in sizes up to 24 teeth -- John Allen.}
|Effective Cycling, at Amazon.com|
|Three-Speed Parts from Harris Cyclery|
|English Three Speeds, Care and Feeding|
|Sturmey-Archer Hubs, General Information|
|Sturmey-Archer 1935-38 Catalogues|
|Evolution of the Raleigh Sports|
Sheldon's old Robin Hood
|Martin Hanczyc's roadster pages.|
Tony Hadland's Sturmey-Archer Pages
including the 1956 master catalogue with
rebuilding information for SWs and others.
|Hubstripping web site|
|John Allen's spreadsheets of internal-hub gear ratios|
|SW Hubs by Brian Hayes|
Jane Thomas's site with
Sturmey-Archer service manuals.
Menotomy Vintage Bicycles
Chat forum on English bikes.
|Articles by Sheldon Brown and others|
Last Updated: by John Allen