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.

endo could have caused a bend, but it really does sound like a worn headset

Almost certainly a notched or warped headset. Possibly caused by the endo. It's unlikely that the crash ovalized the head tube, as the headset would have taken the force and spread it out. I'd start by popping in a cheap new headset, then go from there.

Er, in future this would probably be better for the mechanic's forum.

OK, thanks for the advice. Sorry if I posted in the wrong place. Being I was trying to determine if this was a headset or a frame problem I thought that this would be a good place to find experts in frame geometry and possible effects of warping/bending. I'm sure I would have received good answers in the mechanic's forum as well, as I have in the past.

That's fair, now that I think about it. The question, in a way, boils down to "should I ask a framebuilder about this before I replace the headset"

Ok, yeah, I guess I was just being grumpy. Sorry!

fair question, either place. It's been a long time since I worked in a shop, but I don't remember any front end damage that caused headset problems. Usually, bent frames feel fine and it's only the ones where the bend is extreme that steer funny

UPDATE

New alloy headset with sealed bearings installed. Smooth as silk. No hands = No problem. Narrow wheel and tire still make steering a bit sensitive but the "twitchiness" is gone. Mechanic looked at head tube and frame in general and pronounced them AOK.

Thx for the advice.