Extending a rear axle?
 

I'm trying to build a rear wheel with a Sturmey Archer S2 kickshift hub. The hub I ordered has a 110 mm OLD; the frame I want to use has rear spacing of 120mm. I (wrongly) assumed that I could just put some spacers between the locknuts and the frame, and everything would be fine.

But when the hub arrived yesterday, it didn't fit in the frame. The outside diminsion of the frame is close to 150mm (it's an aluminum frame), and the SA axle is only about 155mm long--too short to tighten the axle nuts on the frame.

Is there any kind of axle extender or adapter I could use in this situation? If possible, I'd like to keep this hub and frame (and not pay any return shipping and restocking fees).

Or should I just eat the cost, learn a lesson, and start over?

Axle replacement isn't all that hard, although it may be a bit more complicated for your hub. Your axle isn't all that long but if you need something really long, you can go to McMaster-Carr. I had an application where I had to to get a much longer axle and was able to order the proper pitch size from them.

I haven't looked inside the hub, but from what I've seen online, the SA axle has a gear right in the middle of it. I'm not sure whether the gear is cast as part of the axle, or whether I could somehow slide the current axle out and slide a longer one in. So far, I haven't been able to find a longer SA axle (one with that gear on it) online.

Correct- the axle has a small pinion gear mounted to it. The gear is a separate piece, but I haven't been able to find the axle separately. SJS cycles in the UK are good for SA parts. If you can get a longer axle, it shouldn't be a particularly difficult job to replace.You'll need a couple of extra spacers as well.

The S2C I just measured and put in my database was 116mm OLD.

So where's that other 6mm?

=8-)

Reading the title I was going to tell you to simply swap the axle but from the sounds of it you need a specific one, the 110 SA hub, is it new or old? (Just curious, don't have helpful input sadly)

I always go on the assumption that if someone put it together, you can take it apart. It may not be easy but...

Looking at this

http://www.google.com/url?source=img...ws-WYdK_NC7r4w

It looks like the axle is separate.

Older one...hmm...seen those in 120mm and 130mm...obviously axle can be charnged...

=8-P

Current production shows 2 axle lengths, 160mm with 120 OLD, and 148 with 110 OLD. The only way I can see to make this work is setting up the long axle version to 110mm OLD and put the no turn washers on the inside facing out, since bending the frame is not an option.

While the axle is separate from the pinion, it isn't simply a matter of drilling a hole through the middle of a standard axle. There are a few important differences.

1- standard axles have rolled threads so the OD in the middle is almost 1mm less than the nominal thread size. The center of SA hub axles has a diameter greater than the ends.

2- SA axles are have side flatted ends to accept a keyed anti-rotation washer. This is a critical feature because the central pinion is the fulcrum for the planetary system, and unless keyed to the frame the axle will spin when torque is applied.

I'm not saying an axle can't be modified to work, or made from scratch, just that it isn't a slam dunk.

Unless a longer OE axle exists, it might make more sense to narrow the rear triangle to match the hub than widen the hub to match the frame.

Thanks for all the feedback!

Here's what I'm thinking about doing: I think I'll order either a HSA 440 (162.5 mm SA axle) or an HSA 571, which is (I think) 175 mm. Then I'll try to replace the original--and see what happens. (Hey--I got started on this whole project because I wanted a "learning experience.")

Stuff like this is a constant reminder to go shopping for a mini-lathe, mini-mill and a bench-top drill press...

=8-P

it's a shame that they don't make Unimats anymore. Everyone should have one.

Yes you need a genuine SA axle IDK if the "Sturmey Archer S2 kickshift hub",
Axle is unique.. SA US is in Cal.
you could see if they erred in sending a hub so narrow.

Very nice...probably exactly what I need...

I swear everytime I go to a machinist sale - it's either wood lathes or heavy duty stuff that's on sale - never the small bench-top stuff....

Will just have to wait to get lucky...almost got a basic 110v lathe with 1/2" or 5/8" chuck I think it was about 6 months ago used for $199.00- someone beat me to it on Craigslist.

I actually make my own Deore HB-M525 axles out of generic M10s - cause it's so damn hard to get the distributors to understand that it's not an M9. Even with the correct Shimano part#, they'll get it wrong.

=8-)

Here's another thought: I might get a pair of these

http://www.niagaracycle.com/product_...ducts_id=33118

and use them instead of the axle nuts, i.e., put them through the dropouts with the heads on the outside, so that they extend inward over the ends of the axle. (The ends of the axle currently reach out as far as the dropouts; they just don't extend out far enough to get the egular axle nuts on them very well.)

I don't have enough experience with this kind of thing to predict whether it will work or not.

"Fits 3/8" x 26tpi ". is your axle that size?

Good point! I'll need to check.

No it's not. It's 13/32"

http://www.sturmey-archer.com/produc.../id/57/specs/1
Besides, those axle extenders require 14 mm dropouts and there would be no provision for anti rotation washers.
To the OP, don't forget to allow for those anti rotation washers in your calculations. They are vital.

Of course, both of those are axles from entirely different Sturmey hubs with completely different physical geometry. You want an HSA768. For every one that wants to whip one out in their garage, here's what it looks like:

Attachment 236715

Choose your alloy carefully and don't overlook post-machining material treatments!

Advice: sell the IHK2F.QBSS.AA0 model you have and buy the IHK2F.QBCS.AA0 longer axle model - or - just get a SRAM Automatix with its 175mm long axle.

PS - The bike measures 120mm inside the dropouts and 150mm outside the dropouts? Seriously - the dropouts are each 15mm thick?

That's the old Sturmey S2 from 1966-1972. The OP has the new hub (2009- ), a completely different design based on Fitchel&Sachs concepts.

Since this is an S2 and not an AW, there actually is no hole through the center of the axle.