vaillanco1

I have been searching unsuccessfully on Ebay for a used Sturmey archer FW hub, but have found a S5 hub. Is it possible to convert a SA S5 five speed hub (1969) to a SA FW four speed? I know they are very similar to one another. I don't want to bother with setting up double shifters to make the 5 speed work.

brianinc-ville

As I understand it, you'd need the special two-part FW indicator spindle, which would probably be at least as hard to find as an entire FW hub. I could be wrong about the latter assertion, though.

rhm

Yes, it is possible. In fact it is fairly common to convert an FW to an S5, so if you can find someone who has made that conversion, you may be able to get the spare parts from him/her.

The conversion parts are usually available from Mark Stonich: BikeSmith Design and Fabrication

The FW has a different (and perhaps hard to find) two piece indicator; and a four-position trigger shifter; while the S5 uses the same ones as the AW hub. But the main difference between the FW and S5 is the primary sun gear, which are essentially the same part but shaped slightly differently. If you knew what you were doing, I believe you could grind the S5 part down to make the FW part. There are a couple other differences, very minor.

All that said, the S5 is the better system. The FW relies on a pair of springs, in series; one is fairly weak, and one is much stronger. When you shift from H to N and from N to L, the stronger spring pushes the weaker spring until it bottoms out. Then, when you shift from L to B, the weaker spring has already bottomed out, so pulling the cable now compresses the stronger spring. It's not easy.

Ed.

The S5 was the typical British-engineered correction for the faults of the FW. I didn't realize the sun gear was 'minorly' different, but neither is something I've messed with very much (I have an S5 on my Mouton, but I've never had the hub apart.)

JohnDThompson 

I have a number of two-piece indicators. They work in SW hubs, but since I've never had a FW I don't know if they're the same or different from the FW two-piece indicator. Anybody know?

noglider 

It won't be hard to get the two shifters going. Go with the S5 as originally intended. Besides, you'll have five gears instead of four.

nlerner

Not the same, unfortunately. And the two-piece indicators that work in an FW are different than the ones in an FM:

rhm

Very helpful! But what about the SW indicator (which is what John has)?

At any rate, if @vaillanco1 can get his hands on any one of these, it would be worth a try. Sturmey Archer indicators are specific length so you can adjust them visually; for example, with an FW indicator you turn the barrel adjuster until the left end of the indicator is flush with the end of the axle. If you used an FM indicator as shown above, the end of the axle would be 7 mm inward from the end of the axle. You might have to add 2mm of spacers to the right end, too; but you could definitely make it work. As for the SW, I don't know; but I suspect he could make it work if he's stubborn (like me).

JohnDThompson 

I'll measure one when I get home tomorrow (currently in Munising MI, far from home).

The ones I have also have an adjuster on the indicator rod itself (see picture above). Perhaps this can be used to compensate for differences in length with the different hub types?

nlerner

I have what I think is an SW two-piece indicator in the bin, so I measured it up and compared it to a known FW indicator:





While the overall lengths are about the same, the different lengths of the wider and narrower parts is key. I tried putting the SW indicator in the FW hub, but the non-drive side half with the longer and larger-diameter barrel wouldn't go very far into the hub.

rhm

Oh, yeah, well ... that will not work.

elcraft

Vince, at Colwood Wheelworks (in the UK; see; Vintage Motorcycle and Bicycle Wheel-building Workshop ) specializes in repair and restoration of Sturmey Archer hubs. He has had exacting replacement indicator spindles re-manufactured for FW and FM hubs (probably has any indicator needed). He w ill have both the expertise and the parts.
That being said, I have never heard of doing the conversion to have less speeds. Classiclightweights.co.uk has an article about an emergency left hand spindle replacement that might be helpful. I can no longer find Tony Hadland's webpages on how the original Lauterwasser conversion was done to turn an FW hub into a a five speed hub. That is disconcerting. Anyone have a link to the process?
Good luck and happy hunting.

nlerner

Mark Stonich/BikeSmith has a set of instructions for that conversion (and also sells the needed bits):

https://bikesmithdesign.com/SA/sa-tips.pdf

rhm

No, I've never seen that! But there's an excellent interview of an aged Jack Lauterwasser no youtube. I presume the process was the same; you need a primary sun gear that hasn't had the corners ground off the dogs. Lauterwasser worked at the Sturmey Archer plant and had access to parts that weren't generally distributed.

Photo courtesy of the internet:



The gear on the axle, at the top, has ramped dogs (that is, the corners are ground off so it won't engage the top gear). The gear lying on the bench has sharp dogs. Take the former off your FW hub, put the latter on, and you now have five speeds.

elcraft

The method that I recall as being the "Lauterwasser Method" had a pin inserted into the left hand end of the axle that was depressed inwards bya metal band. The band was anchored on one side ( using the fender eyelet for example), and then passed over the exposed pin and then a shift cable was attached to the other end of the metal band. The cable then routed into a chainstay mounted fulcrum stop/cable stop. The cable was actuated by a lever elsewhere else (downtube or handlebar). When the cable was stretched, the pin was depressed. This system didnt require any special innards other than an easily fabricated pin. I can recall some of the photos of this crude but effective mechanism. I know that Jack Lauterwasser worked with Sturmey Archer, but this modification annoyed the Engineering staff and he was ordered to cease passing along the technique.

musingsfromjack

For the benefit of anyone perusing this thread I shall offer some corrections and clarifications for the above.


1) FW and FM (Indeed also AF, FC, FB and FG hubs too) all take the same indicator rods. There is however specificity towards axle length. All of the right hand sides of 4 speed rods are the same, but there are two different left hand sides, one for each of the axle lengths. The correct rod from a 5 3/4 inch axled FW will fit a 5 3/4 inch axled FM, but not a 6 1/4 inch axled FW.


2) Two piece indicator rods from 3 speed hubs are different to 4 speed ones. The rod assembly which fits an SW or AM has no common parts with a 4 speed one, they're just different, principally because they aren't controlling any sun gears. In both the SW and AM the axle key can be replaced to allow the fitment of an AW-type indicator rod (more complicated with an SW as you need to grind down an AW axle key to fit).


K hubs also have a 2 piece indicator rod, this is to allow the axle key to be mounted between springs to allow for the elimination of the neutral position (this is also the cause of the wear issues K hub clutches face. NIG hubs are a bad idea. Just set up your gears correctly kids)


3) There are at least 4 different kinds of FW/S5 sun gear. Three have symmetrical square dogs (with different chamfers) and one is severely ramped. The severely ramped version is the most common type found in FW and FG hubs, but any of the 4 is suitable for use in a 4 speed, you just get easier shifting into Bottom gear with the ramped sun gear dogs. Any of the square dogged sun gears can be used in a 5 speed hub, but the ramped version cannot because of the loading of the sun gear in wide-overdrive (the 5th gear).


Just as an FW can be converted into an S5, an FG can be too to make a 5 speed Dynohub. The same principles of conversion (but without the sun gear complexity) can be implemented on an FM or FC/AF hub to make what I would call a 5M or 5C hub. The Top gear on a 5M would be the same 150% of input as that of the S5, so the gear step would be incomfortable, the High (4th) gear remaining at 112%.


In terms of the OP's question of converting an S5 into an FW, the non-threaded axle keys might be hard to find, and the sun gear springs would need to be re-arranged if the hub was an S5/1 or S5/2 because a 4 speed always springs into narrow range, while the later twin-toggle 5 speeds spring into wide range. You would also need to find a compensator spring, which might in fact be the hardest thing to find of the lot. Overall, if you have an S5 and want an FW, go on some Facebook and express interest in a swap, FWs are a lot more common than S5s.


Handily, both FW and S5 internals are fully compatible with AW shells, so a subtle conversion is possible.

nlerner

Jack, I found some differences between the FM and FW indicators I had on hand, both the male and female ends:

musingsfromjack

Your 'FM' indicator is from a hub with a 5 3/4 inch axle and your 'FW' indicator is from a hub with a 6 1/4 inch axle, that's why one of the left rods is 1/4 of an inch longer, it isn't to do with the hub model. As for the right side, the length of this doesn't matter particularly, that's why all hub lengths take the same part. It makes sense that they would have accepted a relatively wide variation in this length as it isn't crucial for the hub adjustment as the adjustment is set on the left.

If you look at parts diagrams you will find that all 4 speed right hand rod/chains are part number K807za (the 'quick release' version has a different suffix) and all left hand rods are K804 for 5 3/4 inch axles and K804A for 6 1/4 axles.

cudak888 

This is one of the easier things to modify. Take two AW keys, drill them out, and cut the flat ends off one of them. Presto, two FW keys.

-Kurt

bluesteak 

I want to revive this thread again, because I have a number of s5 hub and am contemplating converting one to an FW. Most of my questions were answered in the tread, however I bought a 4speed indicator that was used. How far should the two ends thread together? Mine leaves about a 3mm gap where they meet when finger tight, which seems like to much. I am thinking of getting a tiny drill bit to see if I can get some flunk out of the female end. I am thinking between the shoulders I should be able to close it up to 48mm(1 7/8in).

I’m

tcs

Whoa, old thread.

Win a round of Sturmey trivia with this tibit: the SW Mk I (start of production thru October 1958) used a two-piece indicator; the SW Mk II (November 1958 thru end of production) used a one-piece.

bulgie 

I know the OP has long ago decided what to do, but for anyone still reading, it might be helpful to note that there were about 4 different S5 hubs.

1. Original S5 used a bell-crank on the left that pushed on a "nail" (you can use an actual nail cut to length if you don't have the SA part). That pushes the sun gears to the right when you pull on the cable, and they're sprung to the left when the cable is relaxed — same as on the FW.
2. S5-1 used two pull-chains, no bell-crank. So you need an indicator chain on the left as well as on the right. On these the suns are sprung to the right and pulled to the left by the cable, opposite of the original (and the FW)
3. S5-2, uh I forget what was different, I'm sure Sheldon and Tony Hadland can explain it. I think it was considered an improvement, but don't quote me on that, memory is hazy.
4. OK maybe this doesn't count as a separate model, but in 1988 the S5-2 got a modification and some of the parts don't interchange.

I like the original with bell-crank best personally, but the bellcranks are easily damaged if the bike falls over. And hard to find, but I have a small stash of them, a lifetime supply for me. Lacking a SA bellcrank, you can make one out of a Shimano bellcrank — which used to be more common, but nowadays those too are hard to find. Sheldon explains how to tap the threads on the Shimano to fit the SA axle, if you're that desperate. One advantage of the bell-crank style is the internals share more in common with the FW, i.e. conversion is slightly easier.

In my opinion, the S5 (any model) is better than the FW even if you don't use the new high gear, for the simple reason that the FW triggers are inadequate for long-term durability, and they're increasingly hard to find. I rode my FW a lot, practically every day for a couple decades as it was on my urban errands bike. I went through several triggers, maybe a half dozen, and took a couple apart to improve them when new ones weren't readily available. The problem is the catch that holds it in low gets its corner rounded off, to where it easily slips out of gear. Since this is inevitably when you're pedaling hard up an incline, it can result in stripped gears. So whenever I was riding in Low, I would leave my finger wrapped around the trigger, holding it in low so it wouldn't pop out — annoying!

Fixing a worn trigger is non-trivial, you just file on the rounded part to make the corner sharp again, but you have to grind the head off the rivets to disassemble, then you have to rivet it (or bolt it) back together. Then do it all again when it gets rounded off again, depressingly soon if you ride it a lot.

S5 conversion means no more wear-prone and hard to find triggers — just use a common-as-dirt AW trigger on the right, and any friction shifter whatsoever on the left. The left is just two position, on or off, so no "indexing" needed.

I like my Cyclo (Birmingham) toptube shifter on my Super Course, just because it's cute and vintage. A friction thumbie on the Hbar would be more practical.



I turned a 1950s Sturmey clamp-on pulley into a dual-pulley to guide the left-side cable, which was totally unnecessary — any old cable routing will work, including under the BB shell. But a fun project for me:



Here's the chart of S5-2 indicators:


You can probably get away with using the same common-as-dirt AW indicator on both sides on any axle length, if you don't need it to "indicate". That is if you don't need the end of the rod to come flush with the end of the axle for showing you when the gears is adjusted. With the wrong indicator, you'll have to adjust the gears by feel (which isn't hard). Definitely don't waste time hunting for an HSA316 for the left if your axle is 6-3/8" long, because adjusting the left is brain-dead simple if you use a friction shifter as I recommend. I would ignore the indicator when adjusting the left even if I had one. Adjust so that the cable goes just slightly slack when the lever is pushed all the way forward.

Mark B

SirMike1983 

I would not convert a first generation S5 back to an FW. The effort is better spent finding a correct bell crank and getting a proper push rod (either buy or make one). The S5 works fine with a trigger on the drive side and a friction shifter on the non-drive.

Someone made a note awhile back (above) about FW shifters depending on axle length - absolutely true. The axle length will determine the shifter needle/pin length you need. As a short cut, the FG uses the same axles as the FW. Sometimes you can find a defunct FG hub with a longer axle to fit your longer shifter, for example. The 6-1/4 shifters are more readily available today than 5-3/4, so sometimes a longer axle will get you back on the road faster than finding the shorter shifter pin.

The shifter/cable tension in bottom gear on the FW is higher than the AW, but addressed with a good quality shifter and taking some care not to slam in or out of bottom gear. The post-war 3/4 speed triggers are straight forward rebuild. No need to grind the assembly pins - they push through from back to front with an awl or slightly undersized punch. The excess metal at the back end of each pin will fold in on its own as it is driven back through. They can be reused and set after the work is done with a couple careful taps of a hammer backed by the vise top or anvil.

Whether to convert an FW to an S5 is a matter of choice, depending on whether you would benefit from the additional top gear. The early FW hubs from the late 40s into the 1950s are some of the best-made hubs Sturmey produced.

nlerner

@bulgie, I picked up one of these new S-A 4-speed shifters to see if it’ll work with an old 4-speed hub (an FM in this case):

https://www.sturmey-archer.com/en/products/detail/sls40

Haven’t done the experiment yet, but hopefully soon.