I'm looking at some used lugged-steel bikes, and some of them have a minor dent in the frame (top tube), but are otherwise desirable bikes. Does a minor dent compromise the structural integrity of the frame, or should I go for one of these bikes if it's otherwise in good condition?

Minor dents in steel are usually no problem. I'd be reluctant to buy a dented aluminum bike, though, and would NEVER buy a dented carbon fiber one. Steel will deform a great deal before it cracks or tears. This isn't the case with other materials. Even dented steel retains a greater percentage of its initial resistance to deformation than other materials as well. If it's truely a minor dent and the price is right - go for it!

I concur, a minor dent in a steel frame is no problem. I've been riding an early-80's Miyata for over 10 years now with a minor dent in the top tube with no problems at all.

Thanks!

Same here, Small dent on my Trek 820 (Chromoly) top tube. No problems.