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New here and to the tandem would!
Hi everyone, so I'm not stranger to cycling and have had my fair share of rebuild and project bikes. When scrolling marketplace a "free tandem" had just been listed and in my excitement I had to have it! Now, 2 weeks later perplexed and puzzled I'm still sat scratching my head.
I was told by the lovely chap who I collected it from, that it had sat in the pieces I'd picked it up in for some forty odd years. He also said it could be a Sun frame? And believed it to be from around 1915?? I will take some decent photos over the weekend and see what everyone thinks.
So far I have concluded that the bottom bracket is far from standard. It's threaded, but not BSA 1.37. it's around a 37.5mm OD cup size and 37mm ID shell. This is the same for the front eccentric BB housing. So if anyone could shed a little light on that I'd very much appreciate it.
Rear axel has a OLD of 110 and I'm hoping to make it fit to a "modern" 130mm hub, I know I might be pushing it but I'd like more than 3 gears.
The rear dropout also has, what I imagine to be an early attached rear mech hanger, with a larger and threadless hole. Hopefully I'll be able to mount a modern rear derailleur with little modification needed.
Other than that I guess it's just building up the bike like normal? Is there any build threads to reference or anywhere in particular I should be looking for the best knowledge on vintage tandems.
Thank you in advance and I look forward to getting to know a little more about the weird and wonderful world of tandems.
Matt
Hi Matt.
Older tandems will probaly have the oversize Chater-Lea tandem bottom bracket fittings, and also most likely larger headsets than fund on solos. They are not interchangeable with modern ones BUT there may be some thread adapters available (Tandem Club used to sell them years ago). Alternatively you might find a modern oversized press-fit bottom bracket will fit - I know a couple of people have had success.
Rear hubs were narrower in those days, so you could spread the rear triangle a wee bit to accommodate a wider hub - but make sure the rear ends are still parallel otherwise you'll end up with a lot of rear hub bearing issues and probably bent axles.
The 'threadless' rear gear mount is probably for a Cyclo rear derailleur. It was quite common for people to run a three- or four-speed hub gear with a twin sprocket giving a range of six or eight gears on tandems of that era. However, I'd suggest not cutting it off - in case someone prefers to restore it to period components at some date in the future. You should find a modern derailleur with an integral hangar will fit onto the rear ends without too much trouble.
And you should find that a modern eccentric (with 1.37x24tpi threads) will fit in the front, though your one might be narrower than modern ones overall.
Post some pics and the frame number and we can all scratch our heads tring to identify it - but there certainly were a lot of Sun tandem frames around prior to the 1950s.
Best of luck. Let us know how you get on.
Hi Chris, thanks for that info. I'll hunt for a new front eccentric hub so I can fit a sealed BB and modern-ish cranks.
I haven't seen any numbers or marks on the frame but I'll give it a good clean and have a hunt around.
Thanks again
This is the frame set I have. Any guesses from this angle?
