RE: [CR]Question for Strumey Archer experts

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Content-class: urn:content-classes:message
Subject: RE: [CR]Question for Strumey Archer experts
Date: Thu, 22 Sep 2005 00:49:19 -0700
Thread-Topic: [CR]Question for Strumey Archer experts
thread-index: AcW/LBBjt1z2L5YFTruGONEJPsrNDwAG596w
From: "Mark Bulgier" <Mark@bulgier.net>
To: "Mark Stonich" <mark@bikesmithdesign.com>, "Classic Rendezvous" <classicrendezvous@bikelist.org>


Mark Stonich wrote:
> I've converted a few FWs to S5s and the bellcrank is the easy
> part compared to finding an S5 primary sun pinion. Unless
> the FW is a very early one, the sun pinions have dogs that
> are tapered on one side for better shifting. Unfortunately,
> they will transmit force in only one direction.

In case anyone needs a visual aid here, I have a picture of the two sun gears Mark mentions: http://bulgier.net/pics/bike/Sturmey-Archer/4-and_5-speed-suns.jpg or http://tinyurl.com/a4hnx

The 5-speed sun is the one not on the axle - note the square dogs, where the 4-speed has ramps. You can imagine how, when the square-dog 5-speed sun moves over to engage the mating dogs on the axle, the tops of the dogs can hit instead of settling down in between like they should. Crunch! Mark's idea of a spring in-line with the cable on the bellcrank side sounds like a perfect solution to that problem, though I haven't tried it.

Mark Bulgier
Seattle WA USA