Bicycle Mechanics - Sturmey Archer AW problems.

I lent my bike to a friend today. On bringing it home, he reported that while in 1st gear, the hub had suddenly become very rough and grinds in 1st and 3rd gear. 2nd gear is working as normal, but in 1st and 3rd the hub is stiff and 'notchy', leading me to think that it's a problem with the internal gearing.

I've oiled the hub, and as yet it's still rough. Any ideas as to what's causing the problem?

Cheers

Pete

Is the hub adjusted correctly ?How old is the hub ?

It's from february 1989. I just readjusted the bearings and it's got worse- both 3rd and 2nd gear are now direct drive, and in 1st gear the pedals just spin freely. I get th feeling something related to the planet carrier may have finally worn out and snapped.

You'll have to open it up.

Usually if a carrier breaks, the hubs lock up, but it's possible the sun gear stripped, or if pinned to the exle, the pin sheared. Either way try not to ride it until it's fixed because shrapnel floating around will destroy whatever isn't already shot.

I lent my bike to a friend today.,
funny how people don't treat other peoples things
like they would, their own.

are you going to bill them for the time you spend correcting things?

,
funny how people don't treat other peoples things
like they would, their own.



That's true. But there's not much that the user could have done or not done to cause or prevent an internal failure with an SA hub. So I'd give him a pass on this one.

That's true. But there's not much that the user could have done or not done to cause or prevent an internal failure with an SA hub. So I'd give him a pass on this one.

Exactly. He said he was riding the bike normally (he's borrowed it before with no problems) and 'something went clunk'. So if he hadn't been riding it, it would most likely have broken when I next used it.

Well, I've discovered the problem with the ol' AW. I just unscrewed the left side bearings, and not only did the axle come out completely, it was shortly followed by the pin that holds the pinion to the axle, and the pinion itself, snapped cleanly in half. The internals seem to be solidly stuck inside the hub shell, at least I've had no luck removing it with a hammer and nail punch.

Well, I've discovered the problem with the ol' AW. I just unscrewed the left side bearings, and not only did the axle come out completely, it was shortly followed by the pin that holds the pinion to the axle, and the pinion itself, snapped cleanly in half. The internals seem to be solidly stuck inside the hub shell, at least I've had no luck removing it with a hammer and nail punch.

Just what I thought. I assume (hope) you're trying to get the right side ball cup off, and not the left. They can be petty stubborn, and with the hub suspended in the spokes lots of your hammer blow's energy is absorbed in hub movement. Try to improvise a dolly with a block of wood in a vice to support the ball cup with the notch at 3 o'clock, then try driving it with your punch, Use multiple medium blows, rather than lots of taps or one might blow. Also after working on one side, rotate the wheel and work the other. Alternating back and forth you'll get it open if you're patient.

With any luck, the broken bits of the sun gear won't have caused to much secondary damage and you'll only need to replace the 4 planets.

A Hook spanner is the right tool.. but with a broken axle it will be tough to hold it steady.

The axle is still in one piece, the sun gear has just snapped in two, allowing it and it's pin to fall out and releasing the axle. Guess I'll just have to find the right sized hook spanner.

Well, after leaving the hub for a while, I had another crack at it this afternoon. l I finally got the hub open with the aid of a vice, very large adjustable wrench and a hammer. The sun gear is split in two, and the axle key that the indicator rod screws into has also broken. I've found a source of sturmey archer parts (SJS cycles in the UK) so will be gathering a few parts to get this hub up and running again.

I've already rebuilt the wheel with a replacement dynohub, so I guess I'll be getting a new rim and spokes as well to put this into a new wheel. This hub will probably end up on my Raleigh Scorpion, using two sprockets and a rear derailleur to have a half-step arrangement. Alternatively, I might try 'third-step' with a triple crank.

Well, after leaving the hub for a while, I had another crack at it this afternoon. l I finally got the hub open with the aid of a vice, very large adjustable wrench and a hammer. The sun gear is split in two, and the axle key that the indicator rod screws into has also broken. I've found a source of sturmey archer parts (SJS cycles in the UK) so will be gathering a few parts to get this hub up and running again.

I've already rebuilt the wheel with a replacement dynohub, so I guess I'll be getting a new rim and spokes as well to put this into a new wheel. This hub will probably end up on my Raleigh Scorpion, using two sprockets and a rear derailleur to have a half-step arrangement. Alternatively, I might try 'third-step' with a triple crank.

What did you do with the wrench? I thought the left-hand ball cup unscrewed with a hook spanner.

I had to use some not-so-precise techniques. The wrench I have is similar to a pipe wrench. I set the jaws just too close to fit around the right-hand ball ring (in engineering we'd call it a force fit.) Then, with the hub in a vice, bashed it over with a hammer, giving a good grip on the ring. Having got a solid grip on it, it then just unscrewed from the hub without a problem.

It is so rare to hear of AW failures but the pre Sun Race models from the tail end of SA's production do seem to account for most of the issues as QC was at an all time low... 80's hubs do not run as nicely as 70's hubs which do not run as well as 60's hubs and nothing compares to those late 40's and 50's hubs for quality and performance.

On the bright side the replacement parts should be new and of much better quality.

I had to use some not-so-precise techniques. The wrench I have is similar to a pipe wrench. I set the jaws just too close to fit around the right-hand ball ring (in engineering we'd call it a force fit.) Then, with the hub in a vice, bashed it over with a hammer, giving a good grip on the ring. Having got a solid grip on it, it then just unscrewed from the hub without a problem.

I did have to do something similar to get the ball ring out of one of mine a while ago, only I clamped the ball ring gently in a vice and turned the rim. Just out of interest, does the hub have the "No Intermediate Gear" system where the driver has pawls on it, or is it the old-fashioned pronged driver? The NIG ones were produced in the UK for a few years, I'm just curious as to exactly when they started, this might shed some light.

It's the old style four-pronged driver. The hub itself is from february 1989 if that's any help. Unfortunately I already unlaced the hub from the rim in order to rebuild it with a replacement hub, and I only have a mini-vice that won't open wide enough, otherwise I would have tried your method.

Looking at the internals from an engineering perspective, it's actually quite a brilliant design, particularly the way 1st gear is permanently engaged with its own set of pawls to enable it to freewheel in 2nd and 3rd. More gears are great but really nothing beats the 3-speed for its sheer mechanical simplicity.

The hub is fixed :)

Parts from SJS arrived in the post today. The hub itself really just fell back together, no issues at all. IGHs are usually seen as complicated compared to derailleurs, and repairing them something of a black art. With the AW though, everything is straightforward enough that I believe anyone with basic mechanical knowledge and a few tools should be able to service one without difficulty.

Fun fact - the Sturmey-Archer AW hub (http://www.sturmey-archerheritage.com/images/photos/pic-47.1.jpg) is celebrating its 75th anniversary (http://www.sturmey-archer.com/products/hubs/cid/3/id/22).

What did you replace in the end? Just the sun gear and axle key?

Yeah I couldn't obtain the sun gear on its own, so had to buy a complete new axle, along with the axle key.