Originally Posted by
mpetry912
Ferrous materials deform under strain according to Hooke's law of plastic and elastic deformation - see chart below.
Shimmy or frame wobble is usually caused by a pendulous load that gets in resonance with wheel rotation and can grow to very high (scary) amplitude.
However I sincerely doubt that you've strained the material beyond the elastic limit ("C" in the chart below) Had you done so, I doubt you'd be here talking about it.
What I'd suggest is that the frame is fiine - but if you're going to do heavy touring, look at better racks, especially where the racks attach to the frame.
putting 40lb of weight on a rack that attaches to the brake centerbolt is quite likely to result in oscillation at some speeds, in resonance with wheel rotation.
maybe a newly built rear wheel and / or new front wheel would help as well. Or front racks in the "low rider" mode.
but to answer your original question, I wouild bet the frame is OK.
/markp
Thanks for the response. I've checked all the common stress points where steel frames fail (the rare times they do) and I'm not seeing anything that concerns me. On that tour I had a Blackburn Expedition rear rack and low riders up front, plus a big h-bar bag. No matter where I put weight, the bike just complained. Anyway, that's a long time ago and I suspect my bike camping days are behind me. My Miyata would probably thank me for that!