I've got a Trek 700 frameset (chrome moly main triangle) and am wondering about a steering issue. While servicing the 1" threaded headset, I noticed a slight grind even when it appeared to be properly adjusted. I also noticed that it self-centers. There is no ratcheting, which I have seen on other older bikes, just a single pause dead center. I have replaced the bearings but not the headset with no change. When riding no-handed the bike seems twitchy and I have to put more concentration into keeping a straight line than I have had to with other bikes. I blamed the twitchiness on switching from lower pressure 28mm touring tires to a higher pressure 25 road tire on a narrower semi-aero rim, and that is still possibly the culprit as I did not notice this problem before the wheelset/tire switch, so it may be a completely seperate issue from the self-centering. Other than that, the bike rides great.
I built this bike over the winter from a used frameset. I had taken the frameset to the LBS who checked it over and said it was straight and true. The bike was endoed at low speed early this spring, thanks to a big overly-friendly dog. Both I and the LBS inspected it carefully afterwards and found only a few scuffs.
Does this sound like a simple worn headset issue, or are we missing something? I have been wondering if the endo might have caused a slight ovalization of the headtube, or possibly a very minimal bend in the steerer/fork.