Classic & Vintage - 2 sprockets on my SA 3sp

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View Full Version : 2 sprockets on my SA 3sp


chico1st
02-20-11, 12:49 PM
can i put two sprokets facing opposite directions on my SA 3 sp? im wondering if there would be enough spacing between the sprockets for the chain to fit.

has anyone done this? i know people sometimes hack freewheels onto them but i dont really want to do that.


Grand Bois
02-20-11, 01:09 PM
Yes, but they have to be close in size or you won't be able to tension your chain on the smaller one. You just leave out the spacer to make room for two. You're not the first to think of it. A freewheel on a three speed is not a hack.

lord_athlon
02-20-11, 01:22 PM
Yes, but they have to be close in size or you won't be able to tension your chain on the smaller one. You just leave out the spacer to make room for two. You're not the first to think of it. A freewheel on a three speed is not a hack.

This.


Velognome
02-20-11, 02:32 PM
I've been planning to do the same using this Huret pull chain on my '62 sport
190743
Good luck with the conversion, you got to post pics when it's up and running.

wahoonc
02-21-11, 05:47 AM
Yes you can do two sprockets on a SA 3 speed. IIRC the maximum you can get away with, without having to reset the chain every time is a 3 tooth difference. I have seen one where they were running a 22t and a 16t and he had a short piece of chain added in with two release links.

Aaron :)

cudak888
02-21-11, 06:03 AM
Standard SA cogs on 1/8" chain are prone to chain skip. You'd be better off with a Cyclo adapter.

-Kurt

chico1st
02-21-11, 07:51 AM
Standard SA cogs on 1/8" chain are prone to chain skip. You'd be better off with a Cyclo adapter.

-Kurt
What? dont tonnes of people use Stumey archers hubs with 1/8" chains?
or do you mean they are better with 3/32" chains?
and whats a cyclo adaptor?

jonwvara
02-21-11, 08:21 AM
Standard SA cogs on 1/8" chain are prone to chain skip. You'd be better off with a Cyclo adapter.

-Kurt

Not saying it can't happen, but I've used 1/8 chain on a two-cog setup (with 3/32 cogs) for several years, many miles, and a lot of steep hills without any chain skip. Not sure what it would take for it to be a problem.

Grand Bois
02-21-11, 08:32 AM
Standard SA cogs on 1/8" chain are prone to chain skip. You'd be better off with a Cyclo adapter.

-Kurt

I'm not following you.

shipwreck
02-21-11, 08:50 AM
Unless your talking about some sort of derailer system with a 1/8 chain, I don't get that either.
Posted this pic on a simular thread the other day, but here it is again.
http://farm5.static.flickr.com/4154/5225078322_36b1f11e9e_z.jpg
This is one of my long distance rando bikes, genneraly used for two to three hundred km brevets.
One thing, this is a fuji s10s, with amazingly long dropouts, so there is plenty of room to make the change from 16 to 20 without messing with the chain links.

jonwvara
02-21-11, 09:09 AM
Unless your talking about some sort of derailer system with a 1/8 chain, I don't get that either.

Som older derailleurs work fine with 1/8 chain. I know that a Huret Allvit and Svelto will work from my own experience, but I've heard that others will also work.

rhm
02-21-11, 11:19 AM
Standard SA cogs on 1/8" chain are prone to chain skip. You'd be better off with a Cyclo adapter.

-Kurt

I disagree. I have a cyclo adapter with 16T and 19T teeth, which are both too small for my taste. 20 and 23 is a much better combination. You improve the shifting considerably by taking the larger sprocket to the bench grinder and taking the tips off all the teeth, so they have a square top like those on a multi-gear freewheel. If you're feeling artistic you can also give them a slight diagonal facet (look at a modern cassette for inspiration) that will improve shifting a little more.

Bear in mind that the upshift on an AW hub is from a factor of 3 to a factor of 4, so the ideal upshift on the cogs is from 3 to 3.5; so 18 and 21 gives very even spacing. I find it a little high, though; that's why I suggest either 20-23 or 21-24, etc. Any jump of 3T is about right in that region.

gna
02-22-11, 12:31 PM
I have two cogs on my Sports, and 18T and a 21T. I was thinking I would change between the two by resetting the rear axle, but I prefer the 21T.

https://lh6.googleusercontent.com/_6gFs1jHzcfk/TKSj7IFtokI/AAAAAAAAAY8/sZXS8Xr4faM/s640/St%20Paul%20Photo%20Tag%20002.jpg

You may be able to pick out the two cogs in the picture. Just remove the spacer and they fit just fine.

jonwvara
02-22-11, 03:39 PM
My Sprite has 24 and 28 cogs--the four-tooth jump gives basically the same half-steps as a 21-24, I think. I also have a 36-tooth inner chainring (outer is a 52). The bike is effectively a 7-speed, since I only use the 36 with the 28 cog in the 1 setting on the SA hub. It's a bail-out gear of about 25 gear inches--the normal low, which is the 52-28 combo in the low hub gear, is around 37.5. Since I only use the low-low-low on the occasional monster climb, I don't use a front derailleur. Instead, I have to get off the bike and move the chain over manually, which gives me some incentive to power my way up in the 37.5 combo if I can. Not using a derailleur also lets me use a hockey stick chainguard.

BluesDaddy
02-22-11, 10:37 PM
My Sprite has 24 and 28 cogs--the four-tooth jump gives basically the same half-steps as a 21-24, I think. I also have a 36-tooth inner chainring (outer is a 52). I don't use a front derailleur. Instead, I have to get off the bike and move the chain over manually.
This setup fascinates me and I want one eventually. I have a few questions:
How do you manage chain tension with your setup; how do you move the rear axle (wing nuts?); does moving the rear wheel ever cause shift cable adjustment problems with the 3-speed hub?

jonwvara
02-23-11, 07:06 AM
This setup fascinates me and I want one eventually. I have a few questions:
How do you manage chain tension with your setup; how do you move the rear axle (wing nuts?); does moving the rear wheel ever cause shift cable adjustment problems with the 3-speed hub?

I should have mentioned that the rear cogs shift with a derailleur--a Huret Svelto, which has a limit screws that make it easy to limit movement to just two cogs. Other derailleurs will work, but are not so easy to limit.

rhm
02-23-11, 07:17 AM
My Sprite has 24 and 28 cogs--the four-tooth jump gives basically the same half-steps as a 21-24, I think.

Right, the ideal jump being from a factor of 6 to 7, that would be just about perfect. But where did you get a 28T cog? Is it dished like the others?

jonwvara
02-23-11, 08:21 AM
The 28 is a Shimano-splined cassette cog. You clamp it in a vise and use a half-round file to file three of the splines out of existence, then round off the corners on the remaining three so it matches the spline pattern of the SA cogs. Simple to do--only takes half an hour or so, as I recall. Obviously, it's not dished, but if you put the 24-tooth cog (which you can get from Bikesmith Designs) so the dish faces outward and put the SA spacer between it and the big cog, the spacing works out nicely. It did in my case, anyway.
The hard part is finding a steel 36-tooth 116 BCD chainring for the front, if you're as feeble as I am and need that low a bailout gear.

Grand Bois
02-23-11, 09:20 AM
Was the OP talking about using a derailer? I assumed that he was not. That's why Kurt's post and others made no sense to me.

jonwvara
02-23-11, 09:26 AM
Was the OP talking about using a derailer? I assumed that he was not. That's why Kurt's post and others made no sense to me.

I can't speak for the OP, but I think the original question implied using two cogs without a derailleur. It seems to me that this thread has been hijacked by the SA-with-a-derailleur crowd (of which I admit to being one). It might be best to move this discussion to another thread, unless that would confuse things even more.

rhm
02-23-11, 09:26 AM
Was the OP talking about using a derailer? I assumed that he was not. That's why Kurt's post and others made no sense to me.

Ah, good question. I assumed he was talking about using a derailleur. I like to have a low gear when I start from a stop, and shift to a higher gear when I get my cadence up to 110 rpm or something, so I've never considered the idea of multiple cogs without a derailleur.


I can't speak for the OP.... It might be best to let OP clarify the question.

fify!

Grand Bois
02-23-11, 10:45 AM
I think we confused the OP so badly that he left and never came back.

rhm
02-23-11, 11:00 AM
Will we ever learn?

John E
02-23-11, 11:37 AM
I have always used a derailleur when I have put multiple cogs onto a Sturmey hub. My all-time favorite was a 14-16-18-20 Cyclo block designed expressly for the hybrid conversion (along with a longer axle and a bit of wheel redishing). The original bandspring pull-chain derailleur was cr@p and could hit only 3 of the 4 cogs, but an early Campagnolo Gran Sport solved that problem nicely, even w/ the 1/8" chain. I ran a 40T chainring w/ 26" wheels, giving me 10 ratios (and 2 near-redundancies) from 39 to 99 gear-inches. The only thing better would have been a 40-38 or 42-40 ringset up front, to give me 20 closely and pretty uniformly spaced ratios.

With the old school Simplex derailleur shifter in its customary position on the right side of the downtube, I tucked the 3-speed trigger under the left brake handle for easy double shifts at each end of the hub's 2nd gear (direct drive) range.

jonwvara
02-23-11, 01:41 PM
I have always used a derailleur when I have put multiple cogs onto a Sturmey hub. My all-time favorite was a 14-16-18-20 Cyclo block designed expressly for the hybrid conversion (along with a longer axle and a bit of wheel redishing). The original bandspring pull-chain derailleur was cr@p and could hit only 3 of the 4 cogs, but an early Campagnolo Gran Sport solved that problem nicely, even w/ the 1/8" chain. I ran a 40T chainring w/ 26" wheels, giving me 10 ratios (and 2 near-redundancies) from 39 to 99 gear-inches. The only thing better would have been a 40-38 or 42-40 ringset up front, to give me 20 closely and pretty uniformly spaced ratios.

With the old school Simplex derailleur shifter in its customary position on the right side of the downtube, I tucked the 3-speed trigger under the left brake handle for easy double shifts at each end of the hub's 2nd gear (direct drive) range.

Double shifts are one thing, but I draw the line at triple shifts. When I had my Dawes set up with a 3-cog cyclo block, AW hub and 48-32 chainrings in front, I had gears out the wazoo, but there were a fair number of duplicates and trying to remember the shift pattern was beyond me. That's why I set up this bike so almost everything happens on the big chainring--I only use the small one with one cog, and in one of the three hub gears. (Okay, that's a little bit of an exaggeration--I use it mostly in 1, but occasionally in 2 also.)

rhm
02-24-11, 06:35 AM
Double shifts are one thing, but I draw the line at triple shifts. When I had my Dawes set up with a 3-cog cyclo block, AW hub and 48-32 chainrings in front, I had gears out the wazoo, but there were a fair number of duplicates and trying to remember the shift pattern was beyond me. That's why I set up this bike so almost everything happens on the big chainring--I only use the small one with one cog, and in one of the three hub gears. (Okay, that's a little bit of an exaggeration--I use it mostly in 1, but occasionally in 2 also.)

My Fothergill is set up with two cogs on an old Sturmey Archer 5 speed hub; so I have three shifters-- one for the derailleur and two for the hub. There's no duplication of gears, and as long as I stay focused I can usually avoid triple shifts. All in all, though, I'm thinking it's just too much. Complicated shifting makes it less fun to ride the bike.