Re: [CR] Sturmey Archer bursting hubs

(Example: Framebuilding:Brazing Technique)

Date: Fri, 12 Jan 2001 11:28:30 +0000
Subject: Re: [CR] Sturmey Archer bursting hubs
From: "Hilary Stone" <Hilary.Stone@Tesco.net>
To: Troy Warnick <twar@hotmail.com>, classicrendezvous@bikelist.org


Troy Warnick wrote:
> -I would also like to know about the integrity of the Sturmey-Archer alloy
> shelled hubs compared to the steel versions. I have heard that they had a
> problem "blowing up". Does anyone have some experience/opinions here? I am
> going to use a SA hub on a rider and want to make sure I use a durable hub.
> Thanks for any info.
> The two hubs which occasionally appear to burst are the FM (4-speed medium ratio) and FC (4-speed close-ratio). This has nothing to do with the aluminium hub shell ­ just most FM and FCs have aluminium rather than steel hub shells. The cause of the problem is the left-handlow gear side pawl track. The pawls exert pressure on a pawl track which is part of the left hand ball cup. Because space is tight the steel of the pawl track is very thin and the pawl track simply breaks eventually from fatigue. Sturmey were obviously aware of the problem as there are at least two quite radically different designs but neither is 100% reliable in that respect. However the problem is not especially common and not stomping hard in the low gears will help to avoid it happening.
      The FW (4-speed wide ratio) hub does not suffer from these problems as the design is totally different. Most FW hubs have steel shells though there were a few made with aluminium shell.
      All Sturmey gears benefit from careful gear adjustment ­ most damage is caused when a gear is allowed to slip. They are generally very reliable. Hilary Stone