Threading History
05-11-11 | 06:42 AM
#1
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Threading History
I recieved an email from a visitor to my website in regards to threading and the proper designation for British threading. On my site I refer to Britsh threading as 'BSA' because thats how Peugeot referred to it in their catalogs...
Jim
Just been browsing your info on threading and you mention 'BSA' threading. That information is incorrect. BSA (Birmingham Small Arms) Cycles Ltd, a bicycle manufacturer did use a cycle thread 31/31" x 30TPI C.E.I. (Cycle Engineers Institute thread) which is no longer listed under the British Standard/ISO British Standard Cycle threads. The thread size disappeared in the rationalisation of British cycle threads. The standard BSC bottom bracket thread is 1.375" x 24 TPI B.S.C. x 68mm (1 3/8" x 24 TPI in old money. Don't know why they decimalized an imperial fraction) The BSC stands for British Standard Cycle which relates to the type and shape of the threads (adopted from the C.E.I.). The BSC threads are left and right threaded unlike French and Italian which are 35mm x 24TPI and 36mm 24TPI respectively and both cups are right threaded. BSC threads of various sizes were also used for hub axles, pedal axles, headset/fork steerer tube, freewheels seat post pinch bolts. Campagnolo used a unique system of 9mm x 24 TPI axle thread for front hubs and 10mm x 24 TPI for their rear hubs. Most of the modern manufacturers seem to be following Shimano with a metric thread of 9mm x 1mm and 10mm x 1mm for hub axles. Sachs-Maillard tended to use BSC thread on their solid axles and metric on their quick release axles just to confuse the issue! By the by I have found that the allen key expander bolt on the 1980 Peugeot's French handbar stem was 7mm not the standard 6mm. The oft quoted 'BSA' is meaningless as it is a bastardisation which means nothing in engineering terms. It is a oft repeated by journalists in the popular cycling press but just goes to show the extent of how little they actually know and how poor they are at research and checking facts.
Chris
Just been browsing your info on threading and you mention 'BSA' threading. That information is incorrect. BSA (Birmingham Small Arms) Cycles Ltd, a bicycle manufacturer did use a cycle thread 31/31" x 30TPI C.E.I. (Cycle Engineers Institute thread) which is no longer listed under the British Standard/ISO British Standard Cycle threads. The thread size disappeared in the rationalisation of British cycle threads. The standard BSC bottom bracket thread is 1.375" x 24 TPI B.S.C. x 68mm (1 3/8" x 24 TPI in old money. Don't know why they decimalized an imperial fraction) The BSC stands for British Standard Cycle which relates to the type and shape of the threads (adopted from the C.E.I.). The BSC threads are left and right threaded unlike French and Italian which are 35mm x 24TPI and 36mm 24TPI respectively and both cups are right threaded. BSC threads of various sizes were also used for hub axles, pedal axles, headset/fork steerer tube, freewheels seat post pinch bolts. Campagnolo used a unique system of 9mm x 24 TPI axle thread for front hubs and 10mm x 24 TPI for their rear hubs. Most of the modern manufacturers seem to be following Shimano with a metric thread of 9mm x 1mm and 10mm x 1mm for hub axles. Sachs-Maillard tended to use BSC thread on their solid axles and metric on their quick release axles just to confuse the issue! By the by I have found that the allen key expander bolt on the 1980 Peugeot's French handbar stem was 7mm not the standard 6mm. The oft quoted 'BSA' is meaningless as it is a bastardisation which means nothing in engineering terms. It is a oft repeated by journalists in the popular cycling press but just goes to show the extent of how little they actually know and how poor they are at research and checking facts.
Chris
05-11-11 | 07:07 AM
#2
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Interesting and, well, he may be right. What do I know. If he's right, it would be nice if he'd provide some references, not to mention dates, to support what he says. I would be happy to clean up my act and change my ways and all, but if I do, I'm sure people will hypercorrect me. BSA threading is here to stay, irregardless. Speaking of which, 'irregardless' is not a word, but people continue to use it, irregardless.
05-11-11 | 07:40 AM
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Man, a good thread on the history of British threading could go on for pages.
Before Whitworth, just about every machinist shop in the British Isles used their own personal standard threading.
It wasn't until the Crimean War, I think, when the Navy needed a bunch of gunboats in short order, and the department ordered the machine shops to use the Whitworth threading, did any sort of standardized threading occur.
Before Whitworth, just about every machinist shop in the British Isles used their own personal standard threading.
It wasn't until the Crimean War, I think, when the Navy needed a bunch of gunboats in short order, and the department ordered the machine shops to use the Whitworth threading, did any sort of standardized threading occur.
05-11-11 | 06:23 PM
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I can't believe how those blimey brits buid an empire on measures and standards as complicated as quantum physics, and on top of that beat the French with their beautiful, simple elegant metric system!
05-11-11 | 06:34 PM
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05-11-11 | 06:53 PM
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It makes the length of a mans foot, or the reach of Henry I's (1068-1135) arm seem pretty easy to relate to.
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05-11-11 | 07:18 PM
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I read about the history of the meter (and some other interesting measures) in Measuring America by Andro Linklater. Awesome book if you're interested in how surveying was done back in the day and how America began to be divided up.
05-11-11 | 07:23 PM
#14
As long as we're picking nits, French threading for BB is 35 x 1, not 35 x 24tpi. Only the Italians mixed metric diameter and inch pitch (but used a different thread profile angle than the Brits).
05-12-11 | 01:50 AM
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haha well the meter did have a troubled birth... but hey, it's better than the middle ages - for instance, merchants in the Low Countries here in the 15th century had to keep big books with all the currencies and measures used in the trade, and the amount of sizes under the nomer "foot" looks like the assortiment of a well stocked shoe shop 
. In the coinage it was even worse.
. In the coinage it was even worse.
05-12-11 | 04:44 AM
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05-12-11 | 04:54 AM
#19
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05-12-11 | 05:38 AM
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05-12-11 | 06:29 AM
#21
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05-12-11 | 06:44 AM
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05-12-11 | 07:38 AM
#24
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Since I only have a B.A. in History I don't feel the pressing need to take the moral high ground. There is no point in my assuming the moniker of "Historian."
I'm not above anything
Back to threading -it is fascinating stuff.
The question I ask is why did the Taiwanese continue to produce bikes with 26tpi threading when they scaled up production for the early Raleigh-USA bikes? Did they have a big stock of English-made cups they wanted to use up? 24tpi cups were readily available as that is what everone else was using in the Asian factories. I would have thought it would have been a good time to make the transition. Tooling up for 26tpi bb's and forks must have been actually harder than using the standard of the area, but I've worked on these bikes and they still have 26tpi threads for some reason. I can't believe they shipped the tooling all the way from Nottingham to set up their factories. Did they? Or did they spend extra money to make new machines to conform to a backwards standard? Why?
I'm not above anything
Back to threading -it is fascinating stuff.
The question I ask is why did the Taiwanese continue to produce bikes with 26tpi threading when they scaled up production for the early Raleigh-USA bikes? Did they have a big stock of English-made cups they wanted to use up? 24tpi cups were readily available as that is what everone else was using in the Asian factories. I would have thought it would have been a good time to make the transition. Tooling up for 26tpi bb's and forks must have been actually harder than using the standard of the area, but I've worked on these bikes and they still have 26tpi threads for some reason. I can't believe they shipped the tooling all the way from Nottingham to set up their factories. Did they? Or did they spend extra money to make new machines to conform to a backwards standard? Why?
05-12-11 | 10:08 AM
#25
I've always used "BSC" when using an abbreviation for "British" threading...never used "BSA" except when referring to a bicycle or motorcycle of that specific brand (Birmingham Small Arms).
I know that there's a connection between the threading that BSA used on their machines and the BSC threading that was adopted as the British Industrial Standard, but I'm not going to stir the already-muddy waters by using terms that may make sense to someone who's studied British bicycle history, but only confuse everybody else.
I know that there's a connection between the threading that BSA used on their machines and the BSC threading that was adopted as the British Industrial Standard, but I'm not going to stir the already-muddy waters by using terms that may make sense to someone who's studied British bicycle history, but only confuse everybody else.