Sturmey-Archer Cable Pull
 

Greetings everyone,

I'm working on a future (winter) project using a Sturmey-Archer 3 speed hub and I don't have one yet but purchase a wheel after the project gets rolling more. I need to know two things that aren't readily available.

1. The length of cable required to shift the hub from:
a. gear 3 to gear 2
b. and from gear 2 to gear 1

2. The force required to keep the hub in the lowest gear (in ounces?)

I believe that the lowest gear requires the longest cable pull, if I'm wrong just let me know. Imperial or metric measurements are welcome. Any current Sturmey-Archer 3 speed hub is welcome (S-RF3, S3X, ab, etc.). Information on S-A five speed hubs are welcome too.

Any assistance is greatly appreciated.

I can check out the cable pull question for you and get back to you later this morning with that, but I don't have the means to accurately measure for your force question.
I could rig a fisherman's scale to try it with, but I'm not sure how accurate it will be.

S-A AW series of hubs:
Gear 1 to 2: 7.4mm
Gear 2 to 3: 11.2mm

Another thought: Gear 2 must be aligned. Gear 1 happens when the cable is taut. Gear 3 happens when the cable is slack.

Of the current production, the RS-R*3 series, the S3X hubs and the CS-R*3 series Sturmey-Archer three speed hubs have different cable pulls than the AW series hubs.

HTH

1902.

Length depends on the bike’s frame, plus where you put the fulcrum sleeve.
Why not use a standard S/A shifter?

I hope that's not the case. I have a rotary 3 speed still in the box that came with a standard 3 speed shifter.
One thing to note however is the rotary hub is low normal as opposed to the high normal of traditional Sturmey hubs.
EDIT: I just discovered I was mistaken about the low normal bit. I surmised that from playing with the hub without the rotary mechanism attached.
Checking further, I discovered that the spring return is housed in the rotary mechanism, and it is high normal when set up.
EDIT AGAIN: I just placed a call to UBS to enquire about the rotary shifter. It turns out it is indeed a dedicated shifter, and not interchangeable with the classic SA 3 speed.
Learning lots of stuff today.

I just checked a 3 speed trigger shifter on my cable pull measuring tool, and I get 8.6mm for 1 to 2 and 15mm for 2 to 3.
I didn't even try my fisherman's scale on the hub because it has one lb increments very close together. I doubt I could get any useful info for you.
EDIT: See above, the shifter I measured was for the rotary hub, clearly different from the classic shifter as referenced by tcs above.

Yeah, your C30 (rotary gear select) hub probably came with the DLC34 push-push shifter and should say "C30" above the gear indication window. The quite similar DLS30 push-push shifter for the S30 (traditional pull chain gear select) hubs says "S30" above the gear indication window.

You are correct, it does say C30. I confused myself by trying to compare shifters on Sturmey Archer's web site. I should know better than that by now, because they are notoriously slow about updating things like that.

As long as the current hubs are not vastly different I can do fine tuning later. So I guess we're looking at a little under an inch of travel, and less than 2 pounds required to shift.

The reason I need to know this is so I can buy the correct servo for the task (I hope you can see where I'm going with this). It's pretty easy to get a servo to pull ~1 inch of cable at 32 inch pounds (Where A is the angle of servo; L is the length of cable to some center point; length of cable pulled = sqrt([sin(A)^2]+[(L-cos(A))^2]). Now I think I'll be free to get the fastest servo for the job.

Well, fill us in on the result. This is interesting.

Yes, this is a necrobump. But I wanted to thank you for this information. SA's website implies as much but doesn't come out and say it. I spent a couple hours trying to get a trigger to work with an S3X hub to find that it is possible....but adjustment is beyond finicky.

Guess I'll be dropping the coin to get the right shifter.

Yeah, get the right shifter for sure! I destroyed the planet pinions and one of the locking balls in my X-RD5 by using the shifter meant for the X-RD5(W), which has a slightly shorter cable pull.