Whitworth bolt's head size

[Steve kay]

Head size certainly does not always mean cheap Chinese. During WW2 there was a policy of having Whitworth a/f measurements the same as a similar dia BS, the production of very many thousands of tool rolls to accompany transport and weapons etc benefitting from a reduction in the number of spanners needed. Those of us who have built or rebuilt bicycles will have long since accepted that fastenings are often not what they appear to be at first glance. French machines usually being Metric, but Italian bikes into the 80s capable of using Imperial. British machines depending on the manufacturer, Nottingham Ralieghs broadly Imperial but a widespread use of 16 tpi on various diameters, whereas a competition Raleigh from Worksop used differing nuts and bolts. As to the choice of mirror threads on bottom brackets, and Sunbeam's natural use of sizes and threads that Wolverhampton naturally considered superior and thus different, the cycle workshop is full of different tools and a thousand jam jars containing various nuts and bolts. The adjustable spanner does not invariably indicate laziness and lack of moral fibre, it is sometimes the only way to shift an utterly obscure size fastening. As Holmes once remarked to Watson "That man owns a 2CV" "Why, how do you know that Holmes?" "I note an M7 spanner in his tool box."

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