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Sturmey-Archer Bicycle Hubs

by Sheldon "Epicyclic" Brown

Cable Replacement | Cone Adjustment | Dating | 4- & 5-Speeds | Gear Adjustment
Gear Ratios | Lubrication | Planetary Gearing Explained | Links | Taiwan/England

New! On-line Gear Calculator for Internally-Geared Hubs

Quick Reference by Model:
AB	AB/C	AC	AG	AM	AR	ASC	AT3	AW	AWC	BF	BFC
BF/C	BFT	BR	BRC	BRT	FB	FC	FG	FM	FW	GH6	K
KB	KBC	KS	KSW	KT	KTC	S5	S5-2	S3C	SAB	SBF	SBR
Spr.5	Spr.7	ST	SW	T	TB	TBC	TBF	TBFC	TCW	TF	VT

 

Sturmey-Archer Internal-gear Hubs

lmost all English 3-speeds have Sturmey-Archer rear hubs. They made many different models since the company started in 1903. Sturmey-Archer was a division of Raleigh Industries until autumn, 2000, when the parent company ran into financial difficulties. The land the factory stood on was sold, and Sturmey-Archer was nearly liquidated by a corporate raider. Fortunately, a Taiwanese company called Sun Race came to the rescue, and bought the company assets were purchased more or less intact. The machinery and stock have been moved to Taiwan, and it is expected that Sun Race will be resuming production of Sturmey-Archer hubs once their new factory is completed.

Most Sturmey-Archer hubs have two or three-letter model codes, which are usually stamped onto the hub shell. Conveniently, they also usually have the month and the last two digits of the year of manufacture stamped onto the shell. This is the easiest way to date a 3-speed bicycle, if it has its original rear wheel.

Jane Thomas has kindly posted excerpts from the 1956 Sturmey-Archer service manual at:

http://www.toehead.plus.com/st_main.htm

Some Sturmey-Archer Models:

Internal gear hubs
Model	Speeds	Range	Gears(%)	Features
AB	3	Wide	133.3 100 75	With cable-operated drum brake.
AB/C	3	Wide	133.3 100 75	With cable-operated 90 mm drum brake. (current model)
AC	3	Close	106.66 100 93.3	A rare model, made for club bicycles, time trials.
AG	3	Wide	133.3 100 75	Basically, an AW with a built-in Dynohub generator.
AM	3	Medium	115.55 100 86.54	A rare model, made for club bicycles.
AR	3	Ultra Close	107.24 100 93.24	A very rare 1930's model, made for club/racing bicycles. If you have a fast connection, you can see sales brochures for this model.
ASC	3	Close	100 90 75	fixed gear. Extremely rare, and lots of fun! This site has two separate pages devoted to this hub: See the main ASC Page for general info, and the ASC Tech Page for service instructions, cutaway and exploded diagrams.
AT3	3	Wide	133.3 100 75	"Elite" 70 mm drum brake. (current model) "Elite" indicates a hub with an aluminium shell.
AW	3	Wide	133.3 100 75	This is far and away the most common model, introduced in 1936. (current model)
AWC	3	Wide	133.3 100 75	Three speed coaster brake. (current model)
FB	4	Wide	126.6 100 79.9 66.67	With cable-operated drum brake.
FC	4	Close	109.1 100 90 75	A rare model, made for club bicycles.
FG	4	Wide	126.6 100 79.9 66.67	Basically an FW with a built-in Dynohub generator. I have one of these on my 1954 Superbe Roadster
FM	4	Medium	112.5 100 85.7 66.7	A rare model, made for club bicycles.
FW	4	Wide	126.6 100 79.9 66.67	The most common four-speed model.
K	3	Wide	133.3 100 75	The immediate predecessor of the AW If you have a fast connection, you can see sales brochures for this model.
KB	3	Wide	133.3 100 75	With rod-operated drum brake. (Similar to the KBC If you have a fast connection, you can see sales brochures for this model.
KBC	3	Wide	133.3 100 75	With cable-operated drum brake. 1930's predecessor to the AB If you have a fast connection, you can see sales brochures for this model.
KS	3	Close	112.5 100 89.9	A rare 1930s model, made for club bicycles and tandems. If you have a fast connection, you can see sales brochures for this model.
KSW	3	Medium	116.6 100 85.7	A rare 1930s model, made for club bicycles and tandems. If you have a fast connection, you can see sales brochures for this model.
KT	3	Wide	133.3 100 75	Tandem hub with cable/rod-operated drum brake. Similar to KTC If you have a fast connection, you can see sales brochures for this model.
KTC	3	Wide	133.3 100 75	Tandem hub with cable-operated drum brake. Similar to KT If you have a fast connection, you can see sales brochures for this model.
S5	5	Wide	150 126.6 100 79.9 66.67	A modified FW. The original S5 used two cables, a conventional 3-speed type on the right, and a bellcrank/pushrod unit on the left. The right lever/cable has 3 positions, and works as a normal 3-speed hub. The left lever/cable converts the hub from a medium ratio to a wide ratio 3-speed. Since the middle gear is direct drive, the left control has no effect on the middle gear. Most, if not all Sturmey-Archer 4-speeds can be converted to 5-speed. The S5 hubs work well, but the control levers provided with them were very troublesome. The best arrangement for an S5 is to use a standard 3-speed trigger on the right, and a derailer-type friction shift lever on the left (which has only two positions, so ther's no indexing issue.
S5-2	5	Wide	150 126.6 100 79.9 66.67	Similar to the S5, but uses an indicator chain on each side. The S5-2 has a bit more internal friction than the plain S5
S3C	3	Wide	133.3 100 75	Coaster brake. After Consumer Reports rated the TCW IV "unacceptable" due to the fact that the brake would fail completely if the shift cable was misadjusted, Sturmey-Archer completely redesigned their Tricoaster, so that the braking was independent of the gear-change. This model is safer than the TCW series, but is still prone to failure.
SBR	3	Wide	133.3 100 75	"Steelite" 70 mm drum brake. (current model) "Steelite" indicates a hub with a steel shell.
Sprinter 5	5	Wide	150 126.6 100 79.9 66.67	5-speed single cable (current model)
Sprinter 5 Elite	5	Wide	150 126.6 100 79.9 66.67	Aluminium shell 5-speed single cable (current model)
Sprinter 5 Coaster	5	Wide	150 126.6 100 79.9 66.67	5-speed single cable with coaster brake (current model)
Sprinter 7	7	Wide	168 145 124 100 80 69 60	7-speed single cable (current model) See also my article on Seven-Speed Hubs
Sprinter 7 Elite	7	Wide	168 145 124 100 80 69 60	7-speed single cable (current model)
Sprinter 7 Coaster	7	Wide	168 145 124 100 80 69 60	7-speed single cable (current model)
SW	3	Super- wide	138.4 100 72.23	This model was intentended to replace the AW in 1957, but was so troublesome that it was withdrawn, and the AW re-introduced in 1958. The SW uses a unique 3-prong driver, and has crescent shape pawls that don't use pawl spring. When they work, they're very nice. They are light, nearly silent, and efficient. None of the internal parts are interchangeable with other models. See Brian Hayes's article on this site.
T	2	Medium	100 75	A rare 1930s model, made for club bicycles and tandems. If you have a fast connection, you can see sales brochures for this model.
TB	2	Wide	100 75	A rare 1930s two-speed hub with cable/rod-operated drum brake. Similar to TBC If you have a fast connection, you can see sales brochures for this model.
TBC	2	Wide	100 75	A rare 1930s two-speed hub with cable-operated drum brake. Similar to TB If you have a fast connection, you can see sales brochures for this model.
TBF	2	Wide	100 75	A rare 1930s fixed gear two-speed hub with cable/rod-operated drum brake. Similar to TBFC If you have a fast connection, you can see sales brochures for this model.
TBFC	2	Wide	100 75	A rare 1930s fixed gear two-speed hub with cable-operated drum brake. Similar to TBF If you have a fast connection, you can see sales brochures for this model.
TC	2	Close	100 86.54	A rare 1930s model, made for club bicycles. See: sa-1938f2.jpeg (176k) If you have a fast connection, you can see sales brochures for this model.
TCW	3	Wide	133.3 100 75	Coaster brake. Mark I, II, III, IV. Unreliable, replaced by the S3C.
TF	2	Medium	100 75	A rare 1930s fixed gear model, made for club bicycles and tandems. The fixed-gear version of the T If you have a fast connection, you can see sales brochures for this model.
Other Rear hubs
Model	Features
BR	Drum brake for rod operation (similar to BRC) If you have a fast connection, you can see sales brochures for this model.
BRC	Drum brake for cable operation (similar to BR) If you have a fast connection, you can see sales brochures for this model.
BRD	Drum brake for rod operation (derailer-compatible version of BR) If you have a fast connection, you can see sales brochures for this model.
BRCD	Drum brake for cable operation (derailer-compatible version of BRC) If you have a fast connection, you can see sales brochures for this model.
BRT	Tandem drum brake for cable operation (similar to BRC) If you have a fast connection, you can see sales brochures for this model.
SAB	"Steelite" 70 mm drum brake for cable operation (current model)
ST	"Elite" 70 mm drum brake for cable operation (current model)
Front hubs
Model	Features
BF	Drum brake for rod operation (similar to BFC) If you have a fast connection, you can see sales brochures for this model.
BFC	Drum brake for cable operation (similar to BF) If you have a fast connection, you can see sales brochures for this model.
BF/C	90 mm drum brake for cable operation (current model)
BFT	Tandem drum brake for cable operation (similar to BFC) If you have a fast connection, you can see sales brochures for this model.
GH6	Front hub with built-in Dynohub generator.
SBF	70 mm "Steelite" drum brake for cable operation (current model)
VT	70 mm "Elite" drum brake for cable operation (current model)

The Sturmey-Archer AW 3-speed hub

any mechanics are scared of 3-speed hubs, and think of them as being impossibly complicated. The most common model, the Sturmey-Archer model AW, is quite easy to overhaul with the aid of Sutherland's. Other models, especially those with coaster brakes, can be tricky or impossible to repair, due to parts un-availability.

Even if you are too chicken to try taking a 3-speed hub apart, that shouldn't stop you from working on 3-speed bikes. The AW hub is the most reliable gear shifting mechanism ever made, and rarely needs anything more than a bit of medium weight oil every so often. 95 percent of shifting problems on 3-speeds are related to the control cable or the handlebar trigger unit.

When you remove and re-install a 3-speed rear wheel, pay particular attention to the axle washers. The axles are flatted, and there are special anti-rotation washers keyed to the flats on the axles. These washers have tabs that must face into the drop-outs to help keep the axle from twisting under load. The axle nuts are easy to strip because of the interrupted threads on the flatted axle, so you should lubricate them with medium-to heavy oil or grease. They do have to be tightened quite securely.

3-speed cable adjustment

here is a little chain coming out of the right end of the rear axle, to which the end of the control cable attaches. This chain (called an "indicator spindle" by cognoscenti) screws into an internal part of the hub by rather delicate threads. When you install an indicator spindle, screw it in finger tight, then back it off 1/2 turn. It should not be bottomed out on its internal threads, so that it can swing freely to face the cable. This adjustment must be checked every time the cable is re-attached.

The fine adjustment of the cable tension is accomplished by how far the end fitting of the cable screws onto the end of the indicator spindle chain. The official manuals tell you to adjust it by visual examination of the end of the indicator spindle shaft, but this doesn't always work, especially if the indicator spindle is not original equipment. For best results, adjust the cable by tension. When the trigger is in high gear position, the cable should be totally slack. Shift down to middle gear, while watching the indicator chain-it should clearly move as you make the shift. Then shift to low gear; again, you should see more chain coming out of the end of the axle. Sometimes the internal parts line up in such a way as to prevent downshifting. If you have trouble getting the hub to downshift, turn the pedals slightly forwards. Once you are sure you are in low gear, take hold of the indicator spindle chain and try to pull more of it out of the axle. If the adjustment is correct, you should be able to get just a tiny bit more movement from the chain. If it is completely taut, the cable is too tight. Make sure to tighten the knurled locknut on the indicator spindle so that the adjustment will stay as you have set it.

Double check the adjustment in all gears. In low gear, you should be able to see that the sprocket moves faster than the wheel, and the hub should not make a ticking sound while being pedaled forward. In middle gear, the sprocket should move at the same speed as the wheel, and you may hear a slow ticking as you pedal. In high gear, the wheel should turn faster than the sprocket. The same slow ticking may be audible in high gear.

If you hold the trigger halfway between middle and high gear, the hub should disengage so that you can spin the pedals forward without going anywhere. If it freewheels forward in high gear, the cable is to tight or has too much friction to release properly. If it freewheels forward in middle gear, the cable is too loose.

3-speed cone adjustment

one adjustments must only be made on the left side of the hub. A properly adjusted 3-speed wheel will have slight play at the rim. If the cone adjustment is too tight, the pedals will tend to turn forward as the wheel turns. (This same symptom may result if the chain is too tight.)

Gearing

he Sturmey-Archer AW hub provides a direct drive middle gear, a high gear that is 4/3 of the middle gear, and a low gear that is 3/4 of the middle gear. (The principle of operation is explained below.)

By modern standards, the typical 3-speed is geared rather high. Most have 46/18 gearing, which gives gain ratios of 3.83, 5.11 and 6.81 (50, 66, and 89 inches; 4.00, 5.28 and 7.12 meters.) If you cycle in a hilly area, you can make things a lot easier for yourself by customizing the gearing. 20 & 22 tooth sprockets are readily available, as well as smaller sizes for speed demons. It is also possible to modify Shimano cassette sprockets with a Dremel grinder if you need something bigger. This is not particularly difficult to do.

The gear ratios for other models are listed in the table above.

Oil Lubrication

odern bikes use grease for lubrication. This is good, because grease lasts a long time, but it is bad because grease can usually only be renewed by dis-assembling the parts involved. Older 3-speeds were intended for oil lubrication. A bike meant for oil lubrication will have an oil hole in the front hub, covered by a spring clip around the middle of the hub barrel. The bottom bracket will also often have an oil cap. Bikes so equipped should be oiled regularly with a moderately heavy oil, such as Phil Wood, or automotive motor oil. Don't use too much, or you will make a mess, and don't use thin oils or sprays because they don't last long enough.

3-speed hubs always need oil lubrication. The sound of the ticking pawls is a good indicator of the state of lubrication of the hub. If the pawls have a loud, bright tick, the hub may be dry or may have been oiled with too light an oil. A very dull, quiet tick may indicate a hub that has become gunked up with old, dried-up oil. In extreme cases, a hub that has sat unused for a long period of time may get its freewheel pawls stuck, so that it freewheels forward, particularly in low gear. This can often be corrected by lubricating with a fairly light oil and letting it work in.

A drop or two of oil on the moving parts of the 3-speed trigger should also be part of regular maintenance.

How A 3-Speed Works

Internal-geared hubs work on the principle of "planetary gearing."

The basic 3-speed hubs have a single "sun" gear solidly attached to the middle of the axle. A set of 3 or 4 identical "planet" gears mesh with and revolve around the "sun" gear. The "planet" gears are surrounded by (and mesh with) an inside-out "gear ring".

As the planet gears, attached to a part called a "planet cage" revolve, the gear ring revoles 4 times for every 3 times the planet cage goes around. (Some models have different ratios.)

• Low Gear has the sprocket driving the gear ring, while the planet cage drives the hub. Thus, the wheel turns 3 times for every 4 revolutions of the sprocket, lowering the gear by 25%.

• Middle Gear has the sprocket still driving the gear ring, but has the gear ring drive the hub. Thus, the drive is direct. Although the internal gears are always rotating when the sprocket is in motion, they don't have any effect on the drive in middle gear.

• High Gear shifts the sprocket's drive to the planet cage, while the gear ring continues to drive the hub shell. Thus, the hub turns around 4 times for every 3 sprocket revolutions, giving a 33% gear increase.

There is a more detailed explanation of this on the Sturmey-Archer Website, from which I lifted the image above.

Four- and Five-Speed Models

The four- and five-speed versions have two sun gears, which can slide back and forth, so that one of them is locked to the axle, while the other freewheels. The planet gears are stepped gears, with different numbers of teeth at each end. The large end of the planet gears engages the small sun gear, and the small end of the planet gears engages the large sun gear and the gear ring.

Depending on which sun gear is locked to the axle, these hubs are, effectively 3-speeds with a choice of wide or narrow range.

The older, 4-speed versions used a single cable, and only used the wide-range sun gear setting to provide a lower "low" gear. The shift from normal "low" to super "low" ("2" to "1") requires a very strong pull on the gear cable to overcome the spring that controls the sun gears.

The 5-speed versions use two cables:

• The normal one on the right side works as a normal 3-speed.

• There is a second cable on the left side that operates the sun pinion shift.

The original 5-speeds used a "bell crank" to push a rod inward to accomplish the sun pinion shift.

Later 2-cable versions reversed the spring loading on the sun gears, and used a conventional indicator spindle/chain to shift the sun pinions.

Current "sprinter" 5-speeds use a single cable, and rather different internals.

It is not too difficult to convert a 4-speed into a 5-speed, if you can obtain a suitable bell crank. Unfortunately, these are no longer available. I've had some success modifying Shimano bell cranks to fit. I did this by re-threading them to fit the Sturmey-Archer axle. Taps for this purpose are not readily available, so I made a tap out of an old axle.

5-speed Controls

The weak point of the 2-cable 5-speed hubs was always the shift control units. Sturmey-Archer went through a number of top-tube mounted models, which were never very satisfactory mechanically. The left side cable needed to be very carefully adjusted, and the actual mechanics of the click stops in the two-lever controls were too weak, so they were quite unreliable, even though there was no real problem with the hubs.

There was also a problem in that unsophisticated cyclists had trouble mastering the shift sequence of the two separate levers. Sturmey-Archer later made a large and very complicated single trigger control that would operate the two cables, but these were also very temperamental and required a lot of force to operate.

If you wish to use a 2-cable 5-speed hub, the best control arrangement is to use a standard 3-speed trigger for the right cable, and a friction-type derailer shift lever for the left cable. The use of the friction shifter on the left gets around the problem of critical adjustment of the left cable, since you just pull it until it stops.

Taiwan vs England: Quality Timeline

Sturmey-Archer quality had been on a downward slide since the early 1960s, as the company's engineering efforts shifted from trying to make a better product, as they had been through the first half century, to finding ways to make an acceptable product cheaper. Sturmey-Archer's quality peaked probably in the late '50s.

Around the turn of the millennium, Sturmey-Archer (U.K.) was rendered homeless by various corporate maneuvers. For a while it appeared that it would disappear entirely into bankruptcy. A Taiwanese company, SunRace came to the rescue and bought Sturmey-Archer's assets.

They didn't get as good a deal as they thought they were, however!

SunRace spent a great deal of money moving the machinery from England to Taiwan, but when it arrived, it turned out that most of the machinery was worn-out junk, no longer capable of manufacturing parts to the degree of precision appropriate to the 21st century.

I heard an interesting anecdote from a Sturmey-Archer veteran employee, now with SunRace/Sturmey-Archer:

Back in the day, sometimes a batch of internal parts would be just a bit out of tolerance, maybe a bit too small, or a bit too large, whatever. The production people would take a sample to the engineering department, where a grey haired engineer would check it out and often say "Well, it is a bit out of spec, but not really enough to cause failure, so let's let it go."

SunRace didn't have those engineers who had grown up with Sturmey-Archer in their blood, so when they found a batch of out-of-spec parts, they would say "That's out of spec! Melt it down, and make new ones, and do it right this time!"

In any case, the quality of Taiwanese production from SunRace/Sturmey-Archer so far has been excellent, generally better than the quality of later English production. They have also made design improvements, including eliminating the chronic forward-freewheeling issue that used to arise wthen the shift cable was misadjusted.

Some folks don't believe that the Taiwanese can make stuff as well as the British did, but there's no factual basis for that belief, and in many cases this attitude may be traced to racism.

Links

Offical Site
Three-Speed Parts from Harris Cyclery
English Three Speeds, Care and Feeding.
Sturmey-Archer 1902-1952
Sturmey-Archer 1935-38 Catalogues
Evolution of the Raleigh Sports
My old Robin Hood
Martin Hanczyc's roadster pages.
Tony Hadland's Sturmey-Archer Pages
Retro Raleighs
SW Hubs by Brian Hayes
Jane Thomas's site with Sturmey-Archer service manuals.
Menotomy Vintage Bicycles Chat forum on English bikes.

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