Brian Mc

Hello all,

I've ridden several SA 3-speed hubs and I've never felt this slack in a hub before.

In every gear the cranks move about 90 degrees before I feel the hub engage. I don't get any slipping, the hub runs smooth and shifting is fine. I have no idea how many miles are on this hub- the front dropout odometer which was not working when I got this bike only has 2000 miles on it. I took the guts out of the hub, but did not disassemble it. The pawls and everything looked great (to my admittedly novice eye) and the springs had good tension. It's properly lubricated with Phil Wood's oil.

It will have this slack or play in the cranks even when not shifting- after coasting as well. (Yes, I know it's a pernicious habit!)

It is a little disconcerting given that I ride another AW and an AWC(II) which have very little slack in the hubs by comparison.

Any thoughts?

Thanks in advance as usual!

Velognome 

Is the cable binding? Poor cable runs can account for slow shifts

Brian Mc

The cable seems to move freely, I don't believe it is binding. The trigger shifter is light to the touch like my other ones.

markk900

Not sure if its supposed to be like that, but my 49 hub does the same thing. I suspect its OK.

nlerner

I've never thought much about how much lash each of my AW hubs has. They could all be about 90 degrees rotation worth, I suppose. Are your other SA hubs much newer models?

sailorbenjamin

I seem to recall one of the parts in these hubs having a two plane screw thread, so it's possible to assemble the part 180 out of phase. That might add up to 90 of freeplay in a planetary hub.
I don't recall which part it is or even if I'm remembering the right hub but if you google some reassembly instructions and read them carefully, you'll find the part I'm talking about.

Velocivixen

Yes, that could be it. If you watch YouTube "Graham's Garage" when he disassembles a SA AW 3 speed and explains in great detail about it. He says that PRIOR to removing the ball ring , to mark the ball ring AND the hub (I use a sharpie), so that when you go to screw the ball ring back in your can start from the correct side. You would match up your 2 marks to commence. In other words it is possible to screw the ball ring in at two, 180 degrees positions. I don't recall how he explains what happens if you screw it in 180 degrees from where it was originally, but I wonder if this would cause your issue.

Oh, wait. Your problem occurred first, THEN you took it apart? Then my statements would not apply. What was done to the bike PRIOR to you noting the issue? Any maintenance?


I am very interested to find out what the cause is. I'm gonna go check out my bike.

Does it happen inEVERY gear? Does it only happen in certain conditions? If so, what conditions?


OK, so I've disassembled many AW 3 speed hubs. I've seen and read about how they actually work (what parts move in any given gear), but honestly don't exactly understand. I believe that it is the Pawls sticking out (by spring pressure) and the Pawls catch the indented "ratcheted" grooves that all spins when in a given gear. Perhaps one of the Pawls is not catching, causing your crankarm to spin further than normal before engaging.

When you look at a pawl they are black when new. You may not initially see the wear, but look for shiny silver on the pawl corners - if they're shiny silver & not dark, that's an indication of wear and you can replace. If unable to find online (try Harris Cyclery online), go to a bike co-op and they might have bins of old SA hub parts.

agmetal

I just re-checked the Sheldon Brown instructions, and also watched the video that you mentioned, and there was no mention in the video of marking the ball ring, and no explanation in Sheldon's instructions as to what happens if you don't get it aligned correctly. I'm genuinely quite curious about this now, though....

markk900

I believe Sheldon was quoting SA instructions (see Servicing The Sturmey-Archer AW Wide-Ratio Three Speed Bicycle Hub point 2) , but from everything I have read, and from my own experience, there is no real reason to worry about aligning the ball ring. Later SA instructions omit the reference to marking the start point. Whatever it does or does not do, making the engagement point change is not one of them.

southpawboston

I have had several AW hubs spanning several decades of manufacture (1950s-1980s), some rebuilt by me and some never opened, and I've noticed a similar lash in most if not all of them. Not sure if it's 90 degrees worth, but it's there. I've always assumed it's normal.

agmetal

Reading an old paper catalog with service instructions, it says, "The reason for this is that the R.H. ball ring has a two start thread and must be replaced in the same position to avoid having to retrue the wheel after re-assembly".....so, there's the explanation. Nothing to do with the mechanical function of the hub, which satisfies my curiosity (the space between points of engagement on my 1971 AW hub has always bugged me)

agmetal

I took a customer's RS-RF3 equipped bike for a test ride a few days ago and noticed that there seemed to be significantly less lash, and now it has me wondering if there's any way to modify my vintage hub to get the same....

Velocivixen

Great info folks. Thanks for the update. I reread the OP's post and thought that this behavior was new, but they don't actually say that. So I misunderstood.

markk900

You would have thought that if it was that important they wouldn't have had a 2-start thread! I suspect the SA engineers did it for ease of assembly initially.

2manybikes

A small chain ring will increase the pedal travel too.

clubman 

I would think the opposite to be true, the smaller arc of a short crank arm will result in 'perceived' less travel by rider. After all, it doesn't directly affect the lash in the hub.

edit...sorry, I mixed tooth count with crank length. Yes each will alter the perception of the rider, less teeth, more travel, shorter crank arm, less travel.

Brian Mc

I noticed the lash (good to learn the right term) before I disassembled the hub. It happens consistently in all conditions and gears. The pawls did not look mutch different from the other parts. The history of the bike is unknown. It's a well worn Raleigh Lenton Tourist found in Newton, Iowa. Not a very big town, about 15,000 pop now that Maytag left. Sort of a surprising place to find this kind of bike.

I have 1958 and 1968 vintage S-A 3-speeds, both have mutch less lash. I also have a spare AW for parts I got from Iowa Bike Collective, our great local co-op.

Would not both pawls need to consistently skip just the first engagement point for this to happen so regularly?

Sounds like it's not uncommon, but a topic of intrest.

noglider 

Measure the lash in degrees of movement at the cog, not the cranks, for accuracy. The cranks go less than half as fast as the cog.

2manybikes

It's not just perceived, the crank turns the cog a different amount depending on the size of the ring and the cog. This is how bicycles have gear ratios. Also called gear inches.

clubman 

Totally agree but crank arm length doesn't factor into gear inches, recognizing that you didn't imply that .
Sheldon incorporates crank lengths into his 'gain ratio' calculator but I'm currently obsessed with cranks due to complications from knee surgery. I'll never turn 175mm cranks again and even 165 - 170s are uncomfortable.
Sorry to derail thread.

corrado33

Does this happen when you're stopped? What about on the stand. If you shift, then let the bike coast for a while without pedaling does it still happen?

I'd suspect a sticky "shift bar." There is generally a neutral between the gears on the old 3 speeds. If it's slow to shift it'll catch that momentarily.

Velocivixen

When you use the term "shift bar" are you referring to the indicator pin - the pin that screws into the axle with the chain on it?

2manybikes

Not really derailed. It's related. The cranks on the dog trike are 140's. I had to measure them, I did not know they existed. I had that up to 200 rpm once. I can ride it at 160 for a while.
My 2 wheel bikes have 170 and 175 cranks, it's all I can do to hit 160. I have arthritis in both knees, and I found what you did about crank length. But,with a slow warm up i'm OK on the longer cranks. A friend who has a badly damaged knee and short legs uses 165 cranks, I really helps him a lot.

corrado33

Yes, that. Didn't know the correct word for it.

agmetal

More thoughts/questions on SA 3-speed lash:

1. If I lower the gearing overall, will the lash get worse? I'm currently running a 43t ring and 16t cog with a 700x35 wheel, and am thinking about lowering the gearing, likely going with 44/18. As it is, though, the lash bugs the hell out of me and I'm trying to think of ways to get rid of it.

2. Reading a page on Sheldon's site about converting an AW to 2-speed fixed, there's mention of decreasing lash by fabricating a clutch with wider arms or gear pinions with wider heads - is this likely to help at all?

3. Working in a shop, I've test-ridden customers' bikes with more modern SA hubs, like the S-RF3, and I noticed that there seemed to be less lash - I'm wondering if this is due to differences in the number of points of engagement/ratchet dogs. I'm having a brainfart right now and can't think which gear(s) is/are affected by the ball ring, and from pictures it looks like the modern ball rings have more POEs. Will this help at all, and is there any reason I couldn't put a modern ball ring on a 1971 hub? Or am I stuck with essentially what I've got because of the dogs on the left side of the hub shell?