Using a Sturmey Archer Fixed Gear Hub

blueb0ttle2

blueb0ttle2

100 W
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I've mentioned in several articles my desire to change gear ratios without giving up my Ezip's convenient motor mounting arrangement. Many have suggested Jackshafts, but I think I may have hit on a simpler solution.
Sheldon Brown, perhaps in a fit if unorthodoxy, made a LH drive fixed gear bicycle using a rare old Sturmey Archer 3-speed fixie hub. Sturmey Archer still makes a fixed gear hub and I'm thinking, maybe I can have this hub "the wrong way 'round" and get a local machinist to cut some threads on the other side of the hub, so I can put a standard BMX free-wheel there, so that I meet the legal requirement for functional pedals :wink:
 
This is going to sound like a stupid question, but what exactly do the gear ratio percentages mean?
From the Sturmey Archer site..
Gear Ratio
• Overall Range - 160%
• Gear 1 - 62.5% (-)37.5%
• Gear 2 - 75% (-)25% (Gear 1 + 20%)
• Gear 3 - 100% Direct Drive (Gear 2 + 33%)

Does this mean that gear one has 62.5% the number of rpms as Gear 3 (For more torque?) or does it mean that it has 62.5% the number of "teeth" (Like a smaller cog, and therefore more speed).

The hub info is here.
 
Yes, it's output speed in relation to input speed.

It's one of the few hubs that have direct drive in top gear. So, both the ratios are reductive.

You want to put the motor through the hub gears but not the pedals?

There is a drawing of the S3X here: http://3.bp.blogspot.com/_SCUutbkkCn8/SSNGJStUBXI/AAAAAAAAAIo/ZOZHM0FGOgI/s1600-h/S3X+Detail.jpg (it's also available in 130mm O.L.D.)
 
Miles said:
You want to put the motor through the hub gears but not the pedals?
Click to expand...

That's about the size of it. I don't care too much about the pedals having a range of gears to go through, so the pedals will just be driving a single-speed free-wheel on the right side of the hub, unless...I have a dual free-wheel set-up on the "wrong-side" of the wheel. That might be best. I can't really decide until I can have a good look at the hub. I'll do as much research as possible before I dunk any of the green stuff into this project.
 
blueb0ttle2 said:
unless...I have a dual free-wheel set-up on the "wrong-side" of the wheel. That might be best. I can't really decide until I can have a good look at the hub.
Click to expand...
There may not be space for that.

For your first idea, you need to find out if there'll be enough material left after cutting the threads. Core diameter is about 33.6mm.

On the LH side, you'll only be able to use freewheels that screw on from their "outside" (threaded all the way through). You can use the splines on the S3X mount, to stop the freewheel unscrewing.
 
blueb0ttle2 said:
That's about the size of it. I don't care too much about the pedals having a range of gears to go through, so the pedals will just be driving a single-speed free-wheel on the right side of the hub, unless...I have a dual free-wheel set-up on the "wrong-side" of the wheel. That might be best. I can't really decide until I can have a good look at the hub. I'll do as much research as possible before I dunk any of the green stuff into this project.
Click to expand...

I was thinking a 1-2.5 schlumph up front ..how do these sturmey archer hubs work under motor pressure?...heard rumor of a 300 nm torque input sturmey in development not sure how true....and are there losses with these type of hubs?
 
Anyone have first hand experience on how well this hub shifts? I've seen pictures of its insides and its key in slot shifting mechanism that looks like you have to shift at just the right moment to get it to shift smoothly (which wouldn't be much of an issue in an actual fixie pedal only drive where you can "feel" everything but could be an issue without having that feel that an actual fixie gives you).

I've considered doing a mid-drive with re-gen braking capability (freewheeling crank) using one of these hubs (or maybe even two using one as a jack-shaft in the frame for 3x3 gearing) so I could down-shift against the motor in re-gen mod during steep decents just like you do with a big heavy hauling truck.

I love the fact that it is one of the few hubs with the most efficient 1:1 gear being the top gear which is how it should be in my opinion.
 
turbo1889 said:
I love the fact that it is one of the few hubs with the most efficient 1:1 gear being the top gear which is how it should be in my opinion.
Click to expand...
That's to it's advantage, for ebike use - it's disadvantage being its relatively close ratios.
 
Miles said:
turbo1889 said:
I love the fact that it is one of the few hubs with the most efficient 1:1 gear being the top gear which is how it should be in my opinion.
Click to expand...
That's to it's advantage, for ebike use - it's disadvantage being its relatively close ratios.
Click to expand...

Hi Guys
My current status is "dreamer" but I would love to use a Sturmey Archer S3X hub as a motor driven jack shaft on a e-bike build (alas as yet I have not been lucky enough to have even caressed one)
I'm not sure that the S3X output side would be the ideal place for a freewheel sprocket mount if it is similar to the old 3 speed AWs. Perhaps another location may be easier to setup unless you have access to committed engineering?
With the S3X hub would the the ratios be OK using it as a 2-speed jack shaft (1st and 3rd only) ?
Using just 1st and 3rd gear would perhaps permit a simplified shifter to be used possibly a friction shifter assembly with the limits at cable positions for 1st and 3rd?
Good luck with the build blueb0ttle2 (I'm 2green with envy)
Lindsay
 
Conversion of other freewheeling IHGs to fixed gear may also be possible
Apparently a surplus 3-speed SA AW may be converted to 2 speed fixed gear with some committed engineering
unfortunately ratios still would be too close leaving 2nd gear (direct) and 3rd gear +
4 and 5 speed hubs may also be candidates for fixed conversion I've no idea whether the 8 speed and beyond IGHs could be converted similarly

This link: http://sheldonbrown.com/awfixed.html and 2 further links on this page describe some possibilities.
Lindsay
 
Is that hub still going to spin when not in use by the motor? I though a fixed gear had to be constantly pedaled? I'd love to do something like what you're talking about with my Currie kit. I have a 13 tooth freewheel on my motor; standard bike chain teeth. My wheel for the kit is out of commission right now and it's the second one I've had with this kit. I don't feel like spending another $100.00 on a new wheel just to have it crap out on me again.
 
I found this on amazon, http://www.amazon.com/dp/B008ZTLYOE/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=2SRYXRN13FLKU&coliid=I15OPEUCC05UGY. All you would need is a rear wheel hub with a 6 bolt disk mount. I'm actually thinking about buying one for me rear wheel. It comes in 16, 18 and 20 tooth.
 
Avitt said:
ARod1993 said:
Just out of curiosity, does anyone know what the maximum torque input for the S3X that won't void the warranty is?
Click to expand...

I wouldn't recommend putting anything but leg power through the S3X:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=16264&start=75#p917998
Click to expand...

Actually the S3X handles the power of my 750w BBS02 very nicely. This hub works very nicely with 18T cog for city commuting. I don't shift under load. I select my gear then apply power. The shifter key is a concern though, and I can see it shearing off into the hub if i accidentally shift under load.
 
eMax said:
Avitt said:
ARod1993 said:
Just out of curiosity, does anyone know what the maximum torque input for the S3X that won't void the warranty is?
Click to expand...

I wouldn't recommend putting anything but leg power through the S3X:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=16264&start=75#p917998
Click to expand...

Actually the S3X handles the power of my 750w BBS02 very nicely. This hub works very nicely with 18T cog for city commuting. I don't shift under load. I select my gear then apply power. The shifter key is a concern though, and I can see it shearing off into the hub if i accidentally shift under load.
Click to expand...

Oh, I didn't say it wouldn't work. It's very solid, once it's in gear...But you can see for yourself what to expect over time. The S3X has no freewheel, the cog is turning with the rear wheel. Unless you're stopping between shifts, there's always some "load".
 
Yeah. Hopefully it lasts a while though. Once it breaks down I will probably invest into something more suitable.
Here it is on my Cannondale Bad Boy 1 with Bafang BBS02 anyway. Improves chainline nicely and is much better with this system than derailleur.

S3xsmall.jpg
 
eMax said:
Yeah. Hopefully it lasts a while though. Once it breaks down I will probably invest into something more suitable.
Here it is on my Cannondale Bad Boy 1 with Bafang BBS02 anyway. Improves chainline nicely and is much better with this system than derailleur.
Click to expand...

Looks really nice!

Well, please do report back on the longevity. If it's survives your soft shifts, I may reconsider using the S3X for a conversion.
 
Hi guys

Update on my Sturmy Archer, I've blown it to pieces! Was riding if front of a bus and gave it considerable load from my engine and legs. Heard a loud crack and no resistance from the pedals and gear key has fused. Maybe the SA is best on cruisers. If fitting a Shimano Alfine 8 so I will see how that goes.

If only the Nuvinci was not so heavy and expensive!
 
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