Folding Bikes - Is my new SA hub ruined? No spring tension.

I crashed my less than one month old Downtube 8H. Although the bike seems 99% OK, there is no longer any tension in the SA hub -- the rotating part that holds the shifter cable 'nut' turns freely without tension, although the hub seems to shift properly in all positions.

When I crashed the chain came off the bike. Is there a spring part I lost? Is there something likely broken or loose somewhere?

This sounds like one for the Mechanics forum...

The spring is deep inside the hub. I don't believe you could break it by crashing the bike. If it broke, it was almost certainly a defective spring.

But I'm not sure I followed your description of the problem completely, so I'm not completely convinced anything is broken. The spring should pull the hub into 8th gear, and the cable pulls it down into the lower gears. Yours turns feely through the whole range?

The spring is deep inside the hub. I don't believe you could break it by crashing the bike. If it broke, it was almost certainly a defective spring.

But I'm not sure I followed your description of the problem completely, so I'm not completely convinced anything is broken. The spring should pull the hub into 8th gear, and the cable pulls it down into the lower gears. Yours turns feely through the whole range?

Yes, normally the spring pulls the hub to 8th gear, and the shifter cable will pull the 'nut' and rotate the fulcrum, with 1st gear at highest tension.

With the shifter cable (and 'nut' which fits into the fulcrum) removed, the hub fulcrum lever has no spring tension between 1st and 8th gear positions. It rotates 'freely' but seems to correctly shift the hub at all gears. There is nothing pulling it into 8th gear.

So I'm wondering if
a) the spring itself broke
b) the spring 'legs' got dislodged from some internal seating through the force of the impact
c) some other pin or piece broke that is not visible to me.

EDIT: one more thing, during the crash the chain came off, and I wonder if there was some sudden tension on the shifting cable, which combined with maybe pedal tension could have damaged the spring internally

Sounds like a bummer, Dave. I agree with your three alternate theories, but cannot speculate which is the case.

I would treat it first as a warranty issue, either with Downtube or Sturmey Archer. In particular I'd try to get Sturmey Archer to recommend a local shop who will diagnose the problem (and fix it). If your warranty is expired, go ahead and take the thing apart and see if you can find what's wrong. The spring in question comes out pretty early in the process. If the spring (or something) is broken Sturmey should be able to send you a new one. If they can't... well, I still have my old hub that got destroyed last year, and I'm pretty sure these parts of it are still okay.

Agree with all of the above.

In addition, there are other possibilities. The spring is held in check by a plastic cup which has 3 small teeth that engage with matching notches in the axle; if forced, those plastic teeth could break as they are quite small, which would enable the gear changing fulcrum to turn freely while still operating the gears. Such force could come from something pushing the cable into the chain when the chain would exert huge force. (The latter happened to me once when a stick got caught and broke the cable by pushing it into the back sprocket. There was no other damage.)

So my bet is on that plastic cup. That wouldn't be a guarantee issue though. I still have a plastic cup from my parts bin, just checked. Still coated with the original grease. You can have that for free, or any other part that might be needed.

Thanks for the replies & offers -- Replacement hub on its way, stay tuned...

Thanks for the replies & offers -- Replacement hub on its way, stay tuned...

From whom?

Thanks for the replies & offers -- Replacement hub on its way, stay tuned...

I picked up my bike last Tuesday and everything is working great. The replacement hub is indeed the XRF8[W] which is the newer wider ratio (325% gear range) of the factory XRF8. The word on the forums is that this is a more robust version.

I did get the old hub back so I will take it apart to see what exactly broke. I didn't get back any of the other parts (locknuts, cable pulley / barrel adjuster / etc) so it wouldn't be too useful if I rebuilt it as a spare. I'm hoping the replacement 'W' lasts for the lifetime of the bike.

I had a first commute ride last Thursday and all is well. With the Phila. area 28" snowstorm and an upcoming one in two days, it might be awhile before I get to ride again!

I did get the old hub back so I will take it apart to see what exactly broke. I didn't get back any of the other parts (locknuts, cable pulley / barrel adjuster / etc) so it wouldn't be too useful if I rebuilt it as a spare.Between us we should be able to get a full one built up. But I don't have the spare pulley and other outer stuff either. But don't hesitate to ask, my spare stuff will eventually end up in the bin as I have no other use for it.