Front wobble on a Trek 520
Hello everyone...I have a Trek 520 touring rig that I built up from a mid 90's (I think) era 520 frame, with a 1" threaded steerer and the stock 520 fork. I run Velocity Dyad rims and 700 x 35 tires. It has never been wrecked. It has never been loaded for touring, and I use it as my primary commuter. I've noticed that, if I take my hands off the bars when I ride, there is a pretty substantial front end shimmy. It happens at pretty much any speed, though it does get worse the faster I go.
Prior to this I had Mavic rims on the bike, and still had the wobble.
Any suggestions on what may be causing this?