[CR] Fender Eyelets: British bike threading is NOT Whitworth!!!!

(Example: Racing:Jean Robic)

From: "Steve Birmingham" <sbirmingham@mindspring.com>
To: <classicrendezvous@bikelist.org>
Date: Fri, 13 Feb 2009 09:43:16 -0500
Thread-Index: AcmN6Wb/VQOUrtxfTAOwVHLSk1s/ww==
Subject: [CR] Fender Eyelets: British bike threading is NOT Whitworth!!!!

Does anyone have some history as to why Campagnolo is 26 TPI?

When I was doing industrial hydraulics I found that Italian machinery companies almost always used British standard pipe for their hydraulic connections, which struck me as being a bit odd as I'd have thought they'd use the DIN standards

The surplus machinery idea only sort of works for me, as I think machinery shortages were pretty universal post WWII. If it was surplus equipment, I would think that they would use some US standard since we had so much that some places are still running WWII surplus machinery.

Steve Birmingham Lowell, Massachusetts USA

Message: 11 Date: Thu, 12 Feb 2009 22:40:09 -0600 From: Mark Stonich <mark@bikesmithdesign.com> Subject: [CR] Fender Eyelets: British bike threading is NOT Whitworth!!!!

At 2/12/2009 04:26 AM -0500, Ken Sanford wrote:
>you don't identify the nationality of the bike. If it is British from
>say approximately 1965 or earlier,then the threading is likely
>Whitworth. If some other nationality then I doesn't know.

British bike threading is NOT Whitworth!!!! (*)

This is a common misconception, because many 26 tpi BSC fasteners had the same nut and bolt hex sizes as Whitworth threaded fasteners so Whitworth tools fit.

26tpi is BSC British Standard Cycle. In most sizes this is a rather fine thread, intended to avoid loosening from vibration on cycles, motorized or not. Whitworth is a much coarser thread, same pitch as UNC in most sizes but with 55 degree threads vs, the 60 degree threads of the BSC and UNC.

I wonder if the 10mm x 26tpi Campagnolo axle threading had something to do with buying British lathes, surplus from the cycling industry, that would only do 26tpi.

Another possibility is that older eyelet threads are the coarser, pre-ISO 5mm x 0.9mm. Mostly on French bikes but IRRC the Campagnolo 1060 dropouts on my Jack Taylor are 5mm x 0.9mm. Screws from old French derailleurs will sometimes work.

(*) There are no absolutes when talking about the British cycle industry so I imagine somewhere, somewhen, something with Whitworth threading was used, but I've never heard or seen of it happening.

Mark Stonich;
     BikeSmith Design & Fabrication
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