What could make a Sturmey-Archer gear hub seize up?

Question

I bought a bicycle today, but the Sturmey-Archer Dynohub is totally seized. The sprocket won't move at all, and it won't freewheel. The toggle chain won't move either, although it can be unscrewed. What could have caused this, and how can I fix it?

Answer 1

It's likely to be rust and bits of oily muck.  If it isn't totally destroyed, you could try an increasing scale of things

1) spray as much WD-40 into it as you can, leave for 10 minutes and retry.  If it moves at all, spray more in, leave it and then move it again.  Keep moving as much as possible to free up the mechanism.

2) Take it to pieces and soak overnight in a bath of machine oil (or 3-in-1 will do).  Reassemble and retry.

3) Take it to pieces and clean off the rust and muck with a wire brush.  Replace any bits that are no longer the shape they started, where the rust has eaten them away.  Then soak in a bath of machine oil or 3-in-1 overnight; reassemble and retry.

4) Take it to a bike shop and/or get them to fit a new hub gear and chain.  It's probably cheaper than trying to repair it if 1) hasn't worked.

By the way, the Dynohub is only for powering the lights.  If you can't freewheel it's probably the gear hub that has seized.

Answer 2

Rust. Spray a bunch of WD-40 into it.

Answer 3

You mean it was like this when you bought it? didn,t you try it first!!

if from a shop, take it back, even second hand goods have to be fit for purpose, and don,t let them get away with "sold as seen", tell them you are going to trading standards.

I doubt if WD40 will solve the problem, it probably needs the pawl springs and/or the pawls themselves replacing, not a job for an amateur, you need an old style bike shop, but it wont be cheap, at least an hours labour charge plus parts, £30 to £50 is my guess, a new hub costs about £60 plus the rebuild cost, so about £80 for a wheel.

Answer 4

Ahhh! The old Sturmey-Archer, makes you proud to be British. I expect that there are years of accumulated detritus lurking in the sprocket - (bits of old teacake, cucumber sandwich crusts etc). Take it down to the Trumpton repair shop double-quick, Mr Miggins will fix it up and no mistake!

Tip top!

Answer 5

Knackered bearings? Years of rust, old grease full of c**p etc. Pull it apart as far a possible and give it plenty with the WD40 and grease. It should free up with a bit of persuasion but it might be pretty ropey depending on how worn it is.