OK.

My girlfriend's bike has a Sturmey Archer AM hub which stubbornly refuses to go into top gear.

I'm pretty confident that it's not a cable adjustment issue - even with the cable completely slack and the chain all the way in, the hub sticks in direct (2nd) gear. In both 1st and 2nd position it stays in the lowest gear. However I adjust the cable I cannot get top gear.

Hub is an early 80s model with no oil hole. It has not had heavy use from the look of it. I have previously attempted to get some oil in where the togglechain enters (Castrol GTX). Today I squirted some WD40 in there in an attempt to free things up but to no avail.

I really don't want to take the hub apart at this stage. Any advice?

When the cable is loose it stays in 3rd gear and will not pull out enough to go into low gear. Roger

That is a bit of a strange one, as if everything is released the hub should go into 3rd. In 3rd gear the outer gear ring turns 4 inner gears, which in turn engage the axle. I would guess the spring is broken or weak and no longer is pushing the driver (a cross shaped piece that slides on the axle) down to the face of the outer gear ring. https://www.users.globalnet.co.uk/~ha...samaintind.htm

When the cable is loose it's in direct gear (i.e. the wheel turns at the same speed as the sprocket). I thought that was always 2nd on a Sturmey. Am I wrong?

No you're right, with the cable loose the hub should be in 3rd gear, (shell overruns the sprocket by 33%). If you have the correct indicator chain (many replacements are not identical to the originals made by Sturmey Archer, so this may not hold) make a note of the shoulder on the rod. In middle gear it should line up with the end of the axle, with the cable slack or off it should spring in about 3/16", and in 1st gear it should be out about 1/8" or so.

Try and see if you can get the three positions. If the rod won't move in far enough try gently pushing it while jiggling the sprocket, there might be a burr or something hanging things up. If once you get 3rd gear, squirt oil down the axle and keep working the rod back and forth until it moves freely through the range. If you feel carefully you'll find a sprocket position that allows the full range without needing to jiggle so working ir loose will be easier.

The mechanism is fairly straightforward, the rod moves a cross shaped "clutch" which is driven by the sprocket and by sliding in and out engages the driven mechanism 3 different ways. If it can't slide freely something is probably chipped or rusty inside and the hub needs service. Sadly, the vast majority of LBS mechanics have no idea how to service internally geared hub, even though it's easy. Let me know where you live, and I might know someone local to you.

Most SA shifting issues are a result of lubrication failure somewhere in the system. If the cable and shifter move freely, the problem is in the hub. I've had good luck squirting generous quantities of WD-40 into the oil port and riding around until it loosens up. If that doesn't work you may have to open it up and take a look inside. Depending on what you find in there, you may be better off finding a replacement wheel, or at least replacement innards from a donor hub.

Take the chain out. It screws in to the hub. Add plenty of oil through there. Gear oil is thicker and will nof flow in as easily as thinner stuff. Put the oil in and leave the wheel on its side for a while.

Make sure the shifter is not rusted or stuck inside. Spray some gobs of WD40 in there, let it soak, and click the shifter a bunch, upwards and downwards, wiping away excess gunk that comes out. I had shifting problems on an SA AW recently, and the shifter was getting stuck between gear 2 and 3, even though the cable, etc. were fine. Also might consider swapping in a replacement cable (cost about 5 bucks at an LBS) and housing, if you haven't already.

OK, let's eliminate some possibilities. It's not the lever or cable at all - problem happens with a completely slack cable. It's not lack of lubrication somewhere in the system. If lubrication in general was the issue the OP would have problems shifting to or using 1st gear. The hub uses the same chain of parts in 3rd as in 1st - that's why the gear ratios are the inverse of each other.

The problem is that the clutch is not going as far in on the hub as it should. As usual FBinNY is accurate about what to try. Once the clutch reaches the proper position for 3rd that gear will work properly unless the gears are damaged, in which case I believe he would still not get direct drive. It's been about 30 years since I overhauled a Sturmey 3sp but I did dozens upon dozens and I would say the problem is indeed something interfering with the clutch reaching the 3rd position, as FBinNY noted.

It's not really that hard to disasemble and service a 3 speed hub - I really enjoyed it. Sheldon give the procedure very well. If parts are damaged you will most likely need to scavenge. Your title says AW hub but your post says AM. I hope the latter is a typo, as if you truly have an AM hub (narrow ratio) that could be more extremely challenging - it's very rare. In that case if the bike has sentimental value you might be better to replace the entire hub.

Thanks for the "As usual". I doubt he has an AM, not only because they're rare, but also because production ended in the '50s or '60s, and he says his hub is from the '80s.

There's another possibility, and that's that he has the wrong indicator spindle (chain& rod). I hinted at this but perhaps didn't stress it enough, because many of the non-original spindles can cause problems.

The correct indicator rod's travel range is from where the shoulder is recessed about 3/16" to where it extends about 3/16". With the shoulder of the rod flush with the end of the axle the hub should be in 2nd (1:1 drive) If he can't duplicate that, odds are that he has the wrong spindle. He should remove it entirely and see if the hub runs in 3rd gear.

If yes, he's found his problem and the right indicator should fix it. If not, there's an internal problem, possibly a bit of rust. Last ditch step, pour in some oil and stick a knitting needle down to gently push the clutch in while jiggling the sprocket. If it pops back then it's a matter of oiling and working back and forth until it slides freely, otherwise it's a rebuild.

Hmm - I don't see how it's possible for the rod to prevent shifting to 3rd - it is smooth so goes in as far as the clutch takes it. The only problems from the wrong rod come when the rod is too long and won't shift to 1st or is too short and it's difficult to find the adjustment point.

Thanks for all the advice. I'll have another go at it as soon as it stops raining...

It's not an AM (I wish), that was a typo. I'd be very surprised if it had the wrong chain - this bike has sat in a shed for most of it's life and even the tyres are original. It's more likely to be an issue caused by lack of use/lubrication.

Incidentally, 2nd gear (direct drive) engages in the third gear position. 1st and 2nd both give 1st. Now, the simple response would be that the cable's adjusted wrong, but I can find the famous in-between neutral gear between 1st and 2nd gear (between 2nd and 3rd on the shifter). In other words, it's in the usual position in terms of shifting, but not between the usual "actual" gears.

I don't know if that means anything to anyone...

You said this has been sitting in a shed for a long time. Have you looked over the housing and cable? If the housing's broken/rotting in any spots, you could be getting mis-shifts from the shifter to the hub...

Maybe you could take some pics of the relevant areas and post them here. That might help someone identify an overlooked issue...

The cable's fine. If you read the original post you'll see the hub won't go in to top even with the cable disconnected, which rules it out as a problem. Thanks though!

It means you don't know AW hubs and your hub is probably fine. You have the cable adjusted 1 gear too loose. The so called dead spot (no engagement) occurs between when the clutch engages the right side output ring, and the planetary cage pins. Meaning it's between 2nd and 3rd gear.

Please disconnect the cable and turn the sprocket with the axle held either in a vise or the frame, see if the shell overruns the sprocket. If yes, that's 3rd gear, pull out the indicator rod a bit and you'll find the dead spot just before it engages 2nd, (1:1 drive), and if you pull it out a bit more you should find low, shell turns slower than sprocket.

I suspect that if you only have 2 gears they're 2nd and 3rd. When AW hubs only have two gears the one lost is usually low, because wear on the ends of the driver keeps it from disengaging the 2nd gear driving pawls, and 2nd gear overruns 1st.

Wow, FB, you're good.

And I would love to find an AM hub. Not keeping my hopes up.

I certainly don't pretend to be an expert on SA hubs, but this still doesn't add up. With the cable disconnected the hub runs in direct 1:1 gear. The shell does not overrun the sprocket.

I can pull out the indicator rod a bit and find the dead spot, a little bit further and I'm in the next gear and the shell turns slower than the sprocket. If I pull it a bit further, there's no change.

I will have a look and check again that I'm not being daft. It's always possible, but I'm 99% sure that what I've described is correct.

I've checked again and what I've written above is definitely accurate.

The behavior you describe is not normal. With a healthy hub, if you took the indicator chain out, you would be in 3rd gear.

But if you pull the rod and find the dead spot, it means you went from 3rd gear on the way to 2nd gear.

I can't figure it out.

Maybe it's time for a teardown. Don't be daunted. It's not that hard.

Are you certain it's a Sturmey Archer AW hub? What are the markings on the shell?

I'm not sure why this guessing game keeps going, especially ones that ignore the original description, which was informative and apparently accurate.

If I had an AW handy I could remind myself of the exact internals and their interrelationship and perhaps make a more accurate guess as to the problem. but there's no point. The hub needs to be taken apart - there is no other fix and no other way to definitively determine what's wrong.

Follow the instructions on Sheldon's site. Once you loosen the cup ring the parts disassemble and reassemble with no tools, are easily put in the proper way if you pay attention to the instructions, and don't require any internal adjustment. Frankly it's much easier than the diagnostic procedure for some cranky external drivetrain problems.

Well, thanks for all the ideas.

You've basically all confirmed my conclusions - i.e. there's probably no easy fix. I'm going to have a bit more of a play with it and haven't given up on the possibility that a combination of oil/wd40 and jiggling about might cure it, but I suspect that it needs a good look, and I'm NOT going to dismantle the hub at this stage. I just don't have enough time / space to turn another ride-able bike into another pile of bits...

Re-reading FB's comments, I suspect more strongly than before that the cable just isn't tight enough.

OK, time for a Sturmey primer. I started to write this but finally found the same thing with some creative searching.

"In low gear, the clutch is moved to the right to lift the (high gear) pawls, driving the ring gear directly so that the ring gear drives the planets with output going through the planet cage and its (low gear) pawls at 3/4 the input speed. With one pair of pawls raised and the other pair driving, the typical clicking sound of AW hubs is absent.

In second gear, (direct drive), the clutch drives the hub body directly through the right hand pawls, making the planet carrier (low gear) pawls click as they lag behind.

Top gear engages when the clutch is fully extended to the left against the planet cage, between the four protruding planet (pinion) pins, to drive the planets that turn the ring gear 4/3 the input speed. In this position, the low gear pawls in the planet cage click as they lag behind. It is the inverse of low gear and hence the reciprocal relationship between low 1/3 down and high 1/4 up with respect to direct drive on AW hubs."

As you can see it's not possible to "go to 3rd on the way to 2nd" nor can 3rd be related to the tension on the cable. Because 1st and 3rd use exactly the same transmission path, but in reverse to each other, the gears and pawls themselves are all intact and working properly. So the cause has to be that the clutch is not able to push against the protruding planet pins (pivots). Occasionally it is necessary to backpedal slightly to engage 3rd but I doubt with all the effort the OP has made that it's that simple.

I know what the problem is, and will explain how I arrived at the diagnosis, but first a mea culpa.

Like others I incorrectly assumed it was a classic indicator or clutch problem, and not having the hub in my hands couldn't know how much indicator travel there was. Then when the OP incorrectly asserted that the dead spot was supposed to be between 1st and 2nd I made the mistake of discounting his other observations.

Just because someone is wrong on one point doesn't mean he's wrong on everything, and I know better. So apologies to the OP. In my defense, it's been over 30 years since I've opened a 3 speed hub (I currently ride an 1903 2-speed fixed hub).

Fact is the OPs hub has all 3 gears, problem is that they are 1= 3:4, 2=3/4 and 3= 1:1, with the dead spot exactly where it belongs between 2nd and third.

AW hub shells are driven by 2 ratchet mechanisms (freewheels in bike parlance, and over-running clutches to the rest of the world). The right side ratchet is part of the ring gear unit which always turns 4/3rds the speed of the planet cage which has the second ratchet. (The reason for the so called dead spot is if the clutch should simultanius engage the planet cage and ring the hub would lock up).

The shell can spin faster than either or both of these freewheel mechanisms, but not slower then either, meaning whichever ratchet is spinning faster drives the shell, over-running the slower one, and that's the key to how the different speeds are selected.

You may want to refer to this cross section view of an AW hub

In 3rd gear the clutch engages the planet cage, which in turn drives the ring at the 4:3 ratio and drives the shell via the right side ratchet.
In 2nd gear the clutch drives the ring gear driving the shell at the same speed (1:1)
Low gear would be impossible because either ratchet would over-run it, so when the clutch is pulled all the way out it continues driving the ring, but withdraws the right side pawls dis-engaging that drive and letting the slower turning planet cage ratchet drive the shell at 3/4 speed.

In the OPs hub, the right side ratchet is permantly dis-engaged, either because the pawls are frozen in the withdrawn position, or because a previous rebuilder removed them, so the hub always defaults to the lower speed option, 1:1 in third, and 3:4 in both 2nd and 1st. Which is exactly how he described the problem.

So again my apologies to the OP for not reading and accepting his observations as accurate, like his hub a part of my brain was dis-engaged.