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I think your Wikipedia link is broken. This one should (lol, will it?) go to the Hiduminium alloys: https://en.m.wikipedia.org/wiki/Hiduminium
I just got completely sucked into reading all of that and then got onto Duralumin and Y Alloy. Had to stop! Interesting stuff, so it’s a casting alloy and needs heat treatment, followed by age-hardening at room temperature for a week. Strikes me that it’s not very stable and I’d wonder about its physical properties being the same after 80 years! I’d wager that many failures might have happened as a result of this or incorrect heat treating. It’s not exactly the strongest stuff to start with either. State of the art at the time though!
Your stem there, check the stem diameter because it’s an early one. Earlier stems for head clip headsets are 22mm compared to the usual 22.2mm and you won’t be able to use it in a fork with a conventional headset. Apologies if you already knew that!
Jonny69-
It has an expander bolt and as far as I can tell that is original. Diameter is between 22mm and 22.2mm depending on where I measure it :D Clamp a little over 25.4 but untightened.
I do wonder about older alloy components failing, specifically handlebars. I searched the internet a lot on the topic a few years ago and found plenty of people saying they wouldn't risk it, but very few reports of it actually happening. One considered write-up I read said they would be very unlikely to fail catastrophically, more like warp and bend.
No problem being told stuff I know. There's plenty of stuff I don't know, so better to risk it!
Pretty much everything about that advert is great. I'm not sure if many would pack 'shaving tackle' or a fountain pen for a cycling holiday these days. Also interesting to read cyclists were covering their steel components with vaseline in the winter!
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Your stem there, check the stem diameter because it’s an early one. Earlier stems for head clip headsets are 22mm compared to the usual 22.2mm and you won’t be able to use it in a fork with a conventional headset. Apologies if you already knew that!
This is a problem I have noticed (the size difference). I guess this may be another of those metric to imperial cock ups.
I suspect the difference may cause a potential danger, because If you use a 22mm stem in a steerer intended for 22.2mm you may cause undue stress on the steerer by overtightening the headclip bolt and crushing the steerer slot down onto the stem.
I have had a steerer fail (see photo below) and I feel very lucky to have escaped without injury - I was going uphill rather slowly when there was a click and suddenly no connection between the handlebars and the front wheel. Ninon at Bicycle Workshop told me that when headclips were common this type of failure wasn't all that rare.
I'd be most interested to hear what others think about this
veloham
clubman
Thanks @clubman and @Jonny69 all great stuff, although I can't say it fills me with enthusiasm for fitting cotters! I have a BSA set to fit to a 1948 Hobbs so it's in my future nonetheless and I'm sure that'll all be helpful.
I've recently got hold of a Reynolds 2 bolt stem, it looks like a really early one to me, wanting to share details and pick anyone's brain that cares to pitch in. I've not seen markings like this before, only the version with "Reynolds" in the recessed bit of the projection. I guess the patent number 1121-36 means a 1936 patent date, which makes sense with the advert I found on Graces Guides from July of that year. [I hadn't realised that R.R. 56 was the Hiduminium alloy rather than a Reynolds model name - details here https://en.wikipedia.org/wiki/Hiduminium.] I have no clue what the markings on the non-drive-side of the clamp mean.
Got a worrying feeling this means I need a 1930s bike to go with it.