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...

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.

Yes, "irrigardless" is "meaningless as it is a bastardisation of" of "irrespective" and "regardless." Plus, it's 26tpi.

Neal

Raleigh used 26 tpi (because they could), BSC is 24 tpi.

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.

So, BGT, British Gunboat Threading?

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!

HMGT (His/Her Majesty's Gunboat Threading), if you please!

Awesome combination of post/signature going on there, conspiratemus!

Beating the French is just a matter of showing up.

"I'd rather have a German division in front of me, then a French division behind me" - Patton (or so they say)

If you think the British system of weights and measures was perverse and complex, read the about the history of the Meter. :rolleyes: It makes the length of a mans foot, or the reach of Henry I's (1068-1135) arm seem pretty easy to relate to.

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.

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).

A good short book about the development of the screw (and screwdriver) is One Good Turn. I forget the name of the author.

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.

When I get my BB taps sharpened the grinders are always interested in what they are used for.

There's always someone who thinks it's funny to say this.

Patton didn't say this, unless you can find the attribution. He did, however, command the French 2nd Armored Division, apparently without major complaints.

I always liked: "How many Fenchmen does it take to defend Paris?"

I see your French Resistance and raise you Vichy France and Milice Française. I'm 1/4 French myself. I think it's better to stick to making light fun of the French in general rather than looking more critically at their sordid history.

As a historian I should be above stereotypes and ethno-specific jokes. I'm not though :)

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'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.

How the same nation that not only brought us the Rolls-Royce Merlin and of course the Raleigh DL-1 also managed to saddle us with Lucas electrics and ... well, there's no decent way of putting it, is there? That whole Mod thing.


In re weights and measures, I have a 1854 copy of The First Mate's Companion Book which basically is a compendium of crib sheets for doing shipping business worldwide at that time. The chapter on weight and measure exchange is longer than the chapter on wreck and salvage rights!

Some interesting links should we wish to return to threading:

http://en.wikipedia.org/wiki/British_Standard_Cycle

http://en.wikipedia.org/wiki/British_Standard_Whitworth

http://www.britishfasteners.com/threads/bsc.html

Not that I am implying Wiki is a definitive source but there are plenty of good references in the citations.

Mark

I read about the British Whitworth threading story in a book about boats that Sailor Benjamin sent me recently.
It said the Navy needed 100 gunboats in a short time, and knew that it couldn't be done the regular way, so some genius had one gunboat built, then disassembled the moving parts and sent each part to a different workshop and had them make 99 exact copies. Then they assembled 100 boats. Supposedly it impressed the world at how fast it was done.

Witold Rybczinsky (spelling of last name not guaranteed). It IS a good short book.

I've been looking into this stuff lately, so maybe it's time to resurrect this old thread? (Pun totally intended.)

I appreciate the effort, and agree with the conclusion, but there is plenty of incorrect information here from your respondent. Let's dispose of that first:

"31/31" x 30TPI C.E.I. ... 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."
Overlooking the fact that 31/31"=1", the 31/32" x 30tpi thread (which I'm sure is what he/she meant) is, in fact, a BSC standard. Used by Chater-Lea for their headsets, and included in the tables I have. (To be perfectly accurate, BSA's headset thread was .9675", which is .0013" smaller than 31/32" = .9688". But close enough.)
Second, there's no such thing as "ISO British Standard." It's one or the other. ISO is an international organization, BSC was standardized by BSI, a British national standards body. And see next paragraph re: ISO thread. Not exactly the same as BSC.
Third, British cycle threads were rationalized twice: by the CEI in 1901, and by the BSI in 1950 as BSC. Most of the CEI standard threads remained in the BSC. Some were replaced, others were added.

"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)"
First, CEI/BSC thread is 1.370" diameter. (Mathematically, 1-3/8" = 1.375" and .005" ain't much, but the CEI/BSC standard was written as 1.370", not the fraction. FWIW, 1.375" is the ISO diameter.)
Many CEI/BSC threads were decimal, not all were fractional, at least not conveniently so.
Second, the BB width is not part of a thread standard. Thread standards in themselves are limited to diameter, pitch, and form. They do not stipulate where such a thread should be used. They may note where it is being used, but they leave the decision where to use a particular thread diameter to the engineers. This, at least, is expressly the case with CEI and BSC. For example, the same 1.370" x 24 tpi thread has, since 1900 and probably earlier, been used for rear hub cogs, and later, freewheels, not just bottom brackets. (Not only that, but BSC was also the standard for British motorcycle threads, which don't have bottom brackets as such, but might use that diameter thread for other things as needed.)
Other, more comprehensive dimensional standards might stipulate a thread length or shell width, such as NJS, JIS, or ISO, for example.

"Campagnolo used a unique system of 9mm x 24 TPI axle thread for front hubs and 10mm x 24 TPI for their rear hubs."
Campagnolo's hollow axles and track axles are, as noted, 9 and 10mm front and rear, respectively. However, all Campagnolo axle pitches are 26tpi. Their front solid road axle (found on early Tipo hubs, rarely seen nowadays) was 8mm.
Not only are the general Italian threads (BB, HS, FW) a mix of metric diameters and inch pitches, they are also Whitworth form, 55 deg. included angle. This is different from British and Metric threads, which are 60 deg. included angle. Not different enough in practice usually to be a problem, but the specification is as such.

"Sachs-Maillard tended to use BSC thread on their solid axles and metric on their quick release axles just to confuse the issue!"
Doubtful. They are most likely adhering to ISO standards, not BSC.
The BSC standard is all in inch units, fractional and/or decimal. They were written as the CEI standard decades before there was such a thing as a hollow quick release axle. CEI/BSC rear axle thread is 3/8" x 26tpi (in decimal, .375" diameter.)
The ISO standard solid rear axle is 9.5mm x 1.0mm. In inch units, that works out to .374" x 25.4tpi. (The BSC standard, in metric units, is 9.525 x .977mm.) BSC solid axle threading is thus, practically speaking, interchangeable with ISO. It is rare that it is not. (The same is true of solid front axle threads of BSC 5/16" x 26tpi and ISO 8 x 1.0mm. 5/16"=.3125"=7.938mm, 8mm=.3150".)
The next size up in the BSC table from 3/8" is 7/16", which is 11.113mm. I suppose rather than adding a .3937" (10mm) size to the table, they decided to work with whatever standards might already exist, whether proprietary or official. That is conjecture on my part, I admit.

"The oft quoted 'BSA' is meaningless as it is a bastardisation which means nothing in engineering terms."
Maybe. Jury's still out on that, for me at least. I have read corroborated statements by the President of BSA in 1900, a year before the CEI standardization, where he claims the "B.S.A. standard thread" is widely used within the cycle industry. It's plausible he is taking more credit than they're due, in order to boost his company's business and reputation; that's his job, after all. But it's as plausibly true as not. If I ever read of a competitor giving credit to BSA for these threads prior to the CEI standardization, that will pretty well settle things, as far as I'm concerned.
One thing that makes me suspicious of his claim is that BSA took a hiatus from cycle parts production from around 1887 to 1893. This is almost exactly the time frame wherein the safety bicycle overtook the highwheeler as the standard "bicycle." And by the time BSA started back up with bicycles, there were many other large companies in the business whose production had not been interrupted. When the CEI took up thread standardization in 1901, BSA were only one of the big players with a representative on the committee. Some of the other members were in direct competition with them. Only a few firms invited to contribute declined to.

It might be fair to say that BSA can lay claim to the form of the thread, as adopted by the CEI, which is to say a 60 deg. included angle and rounded tops and bottoms with a radius of 1/6 of the pitch. As noted, the other elements of the BSA standard, namely the diameters and pitches, were not universally incorporated into the CEI standard. In fact, BSA admitted to being willing to change most of those to be in conformity with the CEI.

By the way, the direction of the "BSA" and CEI 1.370 x 24tpi thread was RH only, as at that time, BB cups were clamped in place by cotters or pinch bolts as you might still see on tandem eccentrics (hence the name, "bottom bracket.") No LH thread necessary. LH thread fixed cups had not yet been invented. First sign I have seen of those is about 1910, nearly a decade after the CEI standardization.

Now, as regards Peugeot referring to British thread as "BSA": The persistence of the "BSA" moniker to describe British threads, especially on the European continent, likely comes from the fact that BSA was one of, if not the largest pre-war manufacturer and exporter of bicycle components in and from Britain. When someone wanted a British thread bottom bracket, they got a BSA brand. Add to that that BSA made the folding bikes that British paratroopers carried and rode when the Allies invaded the continent, and then left behind afterwards, and it's little wonder "BSA" meant "British" there.
In pre-war USA, that was also the case to some extent, since the USA largely adopted British standards for racing bicycles, and much racing bicycle componentry was of British manufacture. Post WWII, it probably didn't get much notice anywhere that the British Standards Institute had rationalized threads again, and that the British thread standard was now called "BSC." Most people in early post-war Europe had bigger fish to fry in their bombed-out countries, and most Americans were buying Schwinns. Even for those who had noticed, "BSC" is just one letter off "BSA," so it's easy to understand why the one is easily confused for the other.

Even if it is true that the CEI/BSC BB thread originated with BSA, it is still rather quaint, if not silly, at this point to insist that BSA be the preferred name, much less the correct name of the threading. It's good to know where it came from, for sure, if that can be definitively determined. But the close involvement of BSA in the CEI, and especially in its "Thread Standardisation Committee," not to mention its endorsement and adoption of the CEI standards, many of which are quite different from their own, shows me that they were quite willing to relinquish to the CEI the responsibility and name of whatever thread they might have contributed, and adopt others that didn't originate with them, regardless of their origins.

If you wish to refer to threads in BSA bicycles prior to November 1901 as "BSA," that is perfectly historically correct. But since that time, the BB thread at least has been adopted now into at least four standards (in historical order): CEI: 1901 , BSC: 1950, ISO: 1991 and JIS: 1993 (possibly earlier). Any parts made since 1950 to the BSC standard should correctly be named as such. If you want to be safe, if not exactly correct, "British thread" is the term to use. ("Not exactly correct", or at least exclusive, because Chater-Lea used a different thread size for some of their BBs that is also included in the BSC standards. Not to mention the Raleigh 1-3/8 x 26tpi BB thread , which is British, of course, but not BSC, and Whitworth thread form to boot. The so-called "Raleigh" 1" x 26tpi was the original CEI thread though.)

"...just goes to show the extent of how little they actually know and how poor they are at research and checking facts."
Quoted without comment. I'd be happy to provide citations for the above information, if you're interested.