Stripped thread Brompton BWR hub

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Brucey
Posts: 35610
Joined: 4 Jan 2012, 6:25pm

Re: Stripped thread Brompton BWR hub

Postby Brucey » 8 Sep 2019, 11:50am

rogerzilla wrote:On Sachs Torpedo 3-speeds, the key often snaps in half. This immobilises the bike as freewheeling causes the chain to tangle.

Knock-off SA indicators often won't thread into a good key becauae the tapered thread on the indicator is so badly forned. There's a reason why some stuff is cheap, and most of it ends up on fleaBay.


the thread is parallel sided with a tapered lead-in, rather than being 'a tapered thread' per se. Having broken one key in a hub, most folk hedge their bets and buy two keys so that they have a spare one to hand in future. This is handy because you can try the parts for fit in the spare key before you fit them in the hub.

FWIW it is often possible to modify a SA key to fit a Sachs hub; this would be expected to make sourcing new toggle chains etc in the future a fair bit easier.

BTW the Sachs torpedo keys often break, I think, because of bad hub adjustment; (something similar can happen in the old SA AW too BTW). If the second gear adjustment is not perfect, the dogs wear to a slight angle, at which point further pedalling causes an unplanned axial load (fatigue load note) on the toggle key. Something similar can happen if you have bare cable routing on a flexible frameset; the key sees a load with every pedal stroke that pulls the cable slightly.

cheers
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