high torque and small applications and anti vibration due to a fine thread / high torque on small screw sizes, so if you think about it, perfect for an air rifle! The "cycle" thread is actually a bit misleading, it's just a another thread form with advantages for the uses it was designed for, ie.
It may well have been that BSA had the dies and tools in house and that Otto (later CEI) threads were near enough for the jobs they had to do on the BSA / Lincoln rifles, to make new tooling would have been no issue for BSA obviously, but why bother if what they had already could do the job, BSA made gazillions of bicycle componants of all sorts well before Air Rifles dropped into their lap so had God knows what capability ready to use. It's been discussed ad infinitum before, threads are just designed and used for jobs to suit in most cases, so the TPI (fine or coarse) depends on a range of factors. Obviously John Knibbs knows, as gets new screws made, and a thread gauge and micrometer will tell you in seconds the pitch and diameter. Hopefully I might get a copy of John's book soon & it will answer this sort of question & a load more too, but in the meantime has anyone any thoughts on this please? Is the thread BSA used actually the Otto thread? If so how did LJ get access to it if it was specific to BSA. Which kind of makes me wonder if LJ was already using the BSA Otto thread.does anyone know if he was or was the thread BSA used an "industry standard" of the time & one which LJ was already using. It's just that I've never seen a BSA spares screw advertised as only fitting a BSA air rifle & not a LJ. Now since these BSA rifles were based on the Lincoln Jefferies design I was wondering what threads LJ used on the rifles he made. I've read that BSA used some peculiar thread sizes on these for various component assemblies like trigger guard screws & it was stated somewhere or speculated that these threads were the same dimensions that BSA used on the bicycles they made "The Otto bicycle thread". I've always had a bit of an interest in older BSA air rifles, never knew that much about them but recently they have really sparked an interest & a curiosity to find out a bit more about them.
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