BurleyCat

I live in moderately hilly terrain and sometimes ride my older (~1951) 3 speed on short jaunts to town. I also provide mechanical help for two friends who have classic 3 spd bikes, and we all could use a lower granny gear at times. The information is probably available elsewhere and there's no doubt a handy formula (Sheldon Brown) I could employ, but I wonder if anyone has personal experience or insight into swapping out the rear cog on a Sturmey Archer 3 spd? I'm not talking about the internals, but the outer hub drive cog.

All the rear cogs I've encountered are 18 tooth, but there are aftermarket 19t, 20t, 21t and up, available. The downside to going too large would be spinning out in top gear, which may not be so bad, but I'm looking for the optimum rear cog choice that helps with moderate climbs and doesn't compromise high gear rideability.

There's a worker owned bicycle co-op in a nearby city that has a bucket filled with Sturmey Archer rear hubs for sale. I could swap out the rear hub if there's good reason to do so. Was there a point in time when quality went down? Were there ever Sturmey Archer hubs with different internal ratios?

jackbombay

A 22 tooth cog works well with the 48 tooth chainring up front.

There were some SAs with different internal ratios, but they are fairly rare, most all SA hubs are the same the AW model.

BigChief 

I think the 1950s were a high point in Sturmey Archer quality. It's very popular here to gear down 3 speeds to varying degrees. For me, upright roadster riding is more of a laid back, take in the scenery sort of riding. Spinning out high gear isn't an issue for me. I find lower gears and a top gear that gives me a comfortable tempo at around 12 mph is more useful to me than the overdrive. My personal preference is a 22T cog with the older 48T chainrings and 20T with the later 46T chainrings. Your 1951 may have a threaded driver so the 3 splined cogs won't work. My 51 Rudge had the threaded type so I installed a splined driver so I could use one of those chromed, dished 22T coaster cogs. Gearing it down made it far more comfortable and useful for me.

BigChief 

the original driver



and the splined driver

BurleyCat

Aha, that's helpful. My Rudge Whitworth has a 48 tooth chainring and my SA hub takes a threaded, not splined, rear cog.

I hadn't considered going above 21t for the cog, so your response is much appreciated. I assume it's highly unlikely to find a threaded, oversize cog.

Dean51 

My Sturmey AW equipped ride is set up with 42 teeth up front and 22 in the back. Indeed, it easily spins out on the flats, but I have a heap of hills to contend with and that is where my set-up shines.

Dean

BigChief 

51 Rudge? cool...me too. Here's mine

BurleyCat

That's a beauty, for sure. Very similar to mine. It was in pieces for awhile and I'm trying to round up all the bits. The rear hub is stamped '50' but I was told it was purchased in '51. Someone more familiar with the brand than I am once called it a Sports model but, unlike yours, I don't see that written anywhere on the bike itself. I don't have the generator front hub or pump pegs and the handlebars have less rise and sweep. Coincidentally, I saw another well preserved example parked outside a gym in Portland Oregon last week. I was tempted to go inside to talk with the owner.

52telecaster

When i set one up its usually with 700c wheels. I use 21 in back and 42 in front this gives me approximately, 40.5 54 72. This is pretty good for cruising around town. Very often i will go with 2 chain rings and do the sturmey archer half step. This for me would be 36 42 on front yeilding 34.7 46.3 61.7. Or in half step order,
About 35 41 46 54 62 72. Not perfect but a very nice range of gears with a comfortable climber and a decent top gear for commuting, plus you can shift down at a stop light.

BigChief 

We tend to date our 3 speeds by the date stamp on the hub. Not that it's entirely accurate, but since there are no official model years and serial numbers are inconsistent, hub dates are plenty close enough. So, around here, yours is a 1950. Stop by the For the love of English 3 speeds thread sometime. It's the hangout for us old English bike lovers.

BurleyCat

700c or 27" rims are tempting, since there's apparently enough room in the fork and rear triangle. I also own a Raleigh 5 spd 27" Sprint and it rolls along very well. Now that I've posted the minimum number to allow me to include an image I'll see if I can manage that.

clubman 

Ebay.UK will surrender them often.

ryansu 

If you haven't already OP check out St Sheldon the Brown on gear ratio calculations and IGH

Pompiere

Shimano uses the same spline pattern for their internal gear hubs, so may be an alternative if you can't find a SA cog.

amedias

This is true, nearly all SA 3 speeds you'll find are AW with the wideratio spread:

-25%, 100%, +33%

There's also an AM medium ratio, but this is rare.

-13.46%, 100%, +15.55%

There is also a close range racing version AC/AR, this is also rather rare.

-7.7%, 100%, +6.66%

There are vintage 4 speed (and modern 5-8 speed too) options too, but again rare, pretty much all the one's you'll see are going to be 3 speed AW.

My approach with SA 3 speeds is to treat them like single speeds with 2 extra gears, which means I want *one* of the gears to be a equivalent to my preferred SS gear, which for me on a light(ish) road bike in moderately hilly terrain is 68-70 gear inches depending on the exact bike.

Obviously there's three ways to achieve this:

option 1 - 'bottom' gear as my SS gear.

This is madness, it would mean riding almost everywhere in the under-driven bottom gear, bad for efficiency and means your only option is two harder gears, discount this setup unless you're a TT god.

option 2 - 'top gear' as my SS gear.

This is less than ideal as it means I'll spend 80-90% of my time in the over-driven top gear so not great for efficiency, but it does mean I have *two* easier gears for steep hills and f'in steep hills respectively. I only have one bike setup like this and it serves a purpose but is not my favourite

option 3 - 'middle gear' as my SS gear.

My optimum setup for SA 3s, ride everywhere like it's my SS, using the direct drive middle gear which is most efficient, but still offers a lower climbing gear and also a 'romping home with a tailwind' gear.

So basically I choose chainring and sprocket as I would for SS/fixed riding and ride it like an SS bike. You could adjust a couple of gear inches either way to suit your terrain and fitness. SWapping the sprocket is dead easy, there's a snapring retaining the sprocket, pop it off, fit new sprocket on the driver and then fit/refit chain and tension accordingly. Obviously if you're going much bigger you may need to add chainlinks. There is an outside chance you have a hub with a threaded driver instead of splined, if this is the case then it's the same thread as a normal track cog.

JohnDThompson 

The splined driver is a drop-in replacement for the threaded driver, and is still readily available. If you're comfortable opening up your hub to remove the driver (which you'd need to do anyway to change the cog on the threaded driver), you could easily convert your hub to use a splined driver.

The threaded driver uses the same 1.37" x 24tpi thread as standard track cogs, and 22T and 24T track cogs are readily available. But if it were me, I'd just convert the hub to use a splined driver. You don't need to open the hub to change the cog on the splined driver.

thumpism 

I have a 22T cog to go on my spare bike but use a Shimano Nexus 24T on my usual ride with its 48T chainring.

BurleyCat

I'll visit the 'Love of English 3 Speed' site. Meanwhile, can you confirm whether a modern track cog will thread directly onto a 1950 threaded SA 3 spd hub? They're more readily available than replacement drivers here in the US. If it's possible, I'm guessing chainline can be maintained with spacers.

BigChief 

AW hubs always have 2 spacers you can use to adjust the chain line. They look to be around 1/16" thick. The Sturmey Archer cogs are 1/8" but I don't think you would have a problem using a 3/32" threaded track cog. But, you can find AW drivers on eBay. I would go that route because there's a wide range of inexpensive 3 splined dished cogs available and they're easy to swap around.. 16T to 24T It would give you room to experiment. On threaded drivers, the outer dust cover is wedged between the cog and driver. You need to remove the cog to get it off. It was easier for me to dig into my parts bin for another cover, so I never removed the original from the threaded cog as you can see in my photo.
I'll say that gearing these roadsters down makes a huge difference. For me at least. Very well worth the effort.

Kovkov

I have:

46x18
46x20
46x21
48x22
46x22
46x23

That‘s the nice thing with 3-speeds. You can have 18 speeds not on one bike but on 6 of them

John E

Absent a multi-cog block in back, that is what I would do with a wide range 3-speed, as well, to "fill in the gaps."

My favorite setup with a Sturmey AW hub was a 14-16-18-20 cog block, which gave me 10 non-redundant ratios from about 40 to 100 gear-inches with 26" wheels. I used the three larger cogs with first gear, all four with second/direct drive, and the three smaller cogs with third, which kept me in the most efficient direct drive most of the time, except when climbing or descending.

JohnDThompson 

Yes, it will. But as noted above, you'll need to open the hub and remove the driver with the cog attached, secure it so it can't rotate, and use a chain whip to remove the cog. This is how I secured mine:



Bike Tools Etc. shows the splined driver (HSA-123) in their on-line catalog:

"67. DRIVER for PRE-NIG AW HUB (Item #SU-HSA123) $22.95"

Otherwise, I might have a used one here in my Sturmey-Archer pile.

Many Sturmey-Archer cogs are dished, so you can adjust the chainline by turning the dish to face in or out as needed, as well as moving the cog spacers.

Moe Zhoost

OK, now I know what I want for my birthday.

palincss

I always found one of the biggest problems with the Sturmey AW was that the high gear was just too high. For me, a larger rear sprocket helped the DL-1 I rode to work from 1980 - 1985 enormously by making the high gear actually usable. As for "spinning out in top gear" - impossible with a DL-1. That bike has the two-wheeled equivalent of "hull speed" and even downhill with a tailwind you just can't go that fast, and as high as the high gear is in stock configuration, I never was able to spin out top gear.

(And after writing this, I read another post here Road Test/Bike Review (1978) Four 3-Speed Commuting Bikes that reprinted road test reviews of several 3-speed commuting bikes, including Frank Berto's take on the Raleigh Tourist (aka DL-1), where he says it was hard to pedal and its gears were much too high and recommended changing the rear sprocket from the stock 19T to 22T or even 24T. I'll bet I read that review back in 1978; and when I got one of my own in 1980, one of the first things I did was replace the rear sprocket with I believe a 24T.)

BurleyCat

Maybe someone here can identify this driver? I'm away from home and dropped into a bike shop known for an eclectic selection of vintage and obscure parts. I purchased it even though it does not match images of the Sturmey Archer 3 spd drivers that I've seen.