Frame alignment question
 

I have an old steel road bike that I can't ride no handed. It always wants to fall over to the right. I have eliminated wheels as a cause of the problem. I did Sheldon's frame alignment test, and the string is about 2mm farther from the seat tube on the right side than the left. To say this another way, the right chain stay is farther from the center of the bike than the left seat stay is.

I have two questions before I try to bend the rear end of the frame. First, the magnitude of the misalignment--it doesn't seem that great to me. It's not like the bike pulls a bit, it is really impossible to ride without hands. I'm wondering if a 2mm difference is enough for that. Second, as far as I can picture this in my head, this makes the bike like this:

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(looking from the top, up is front)

I'm not sure this is consistent with the bike's no-hand behavior, which is the front wheel turning sharply to the right by itself.

I might bring the fork in somewhere to be checked tomorrow to see if that isn't the true cause. It looks alright visually. I am kind of mystified at the moment.

1 or 2 mm is not that bad, have you checked the fork??? The wheel is at the center or is going to one side of the fork? Pretty in my experience the problem is more the fork than the frame. Just wonder if both fork blades are bent to the left maybe?

If you hold the bike by the seatpost and lift it off the ground with the front wheel hanging straight down, then turn the handlebars to one side, does the wheel return to center immediately and on its own? If not, the problem is probably a headset that is binding.

The seat tube is also only half way to the rear dropouts, so 2mm on the string test is closer to 4mm at the dropouts. I have seen way worse than 4mm off in the past, but 4mm is still not good.

I've tried...I took it off and looked at it for a while, and I measured from the middle of the top of the steerer tube to each tip and didn't find anything amiss. Was going to take it to a shop, there is some fork-checking tool right?

I didn't do exactly that (I'd do it right now but the fork is off) but I don't think the headset was binding...still it is a potential culprit, I replaced the bearings a while ago and it's possible I did something wrong.

Hmm good point.

Happy ending
 

Did Sheldon's 2x4 frame realignment method. Also took the fork to the LBS where it was skewed, and they yoinked it back to true. One or both of these things worked-- no-hands is now perfectly normal on this bike. Thanks Bikeforums.net!

Good man, havent done that ever hahaha :) One of the repairs i have never done :D

You may want to flip both your wheels to check they haven't been incorrectly dished at some point...