Speed Wobble when Touring on old Dawes Super Galaxy

Hey all,

So I've had this problem for a while and I'd be interested in putting it out there for all you bike nerds to discuss. I guess ideally I'd like to find out if there's anything I can do about it but I imagine it's something inherent to the frame at this point. Anyway I've had this 58cm Dawes Super Galaxy for about 11 years now, cycled many places between Ireland and Istanbul on it and most recently 3,000km in Eastern Canada in 2019. On that most recent tour, I got a lot of speed wobbles - only, they weren't even speed wobbles, they were just wobbles. They would occur sometimes going pretty slow actually, as well as at higher speeds, the frame oscillating back and forth under me, sometimes pretty violently, despite changing grip on the bars, position on/off saddle, or hugging the top tube with my legs. Weirdly enough, at a certain point they seemed to be really bad in the morning and then fade a bit throughout the day (again irrespective of speed). It was bad enough though that I've been thinking before I do another tour I might want to get another frame. But also, I love my frame, and I'm a cheapskate and don't want to buy another. Is there anything I (or an experienced frame-repairer) could do to mitigate this problem? Or is it just down to the flexibility of an old steel frame?

I generally don't get the wobbles when the bike is not loaded, so I imagine that's also a major factor. But what use is a bike frame you can't load down with a ridiculous amount of stuff?

Oh yeah and also before that tour, one of the seat stays popped off the seat tube - I got that repaired by a frame-repairer in Edinburgh.

Cheers for any thoughts, here's a photo of the steed

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