I was trying to take a pic today of the sunset, going down hill at 30 mph or something like that, and with no hands on the bars, the front of my bike started to wobble back and forth pretty good. my body was stabilizing the rear wheel, and i went nowhere, but that wobble was kind of surprising, and I never noticed it before.

I'm a 6' - 6'1" guy on a 56 cm caad9, 15.5 cm head tube, with a slammed -17 deg 140 mm stem. pretty short wheel base.

Does this wobble happen because of the short wheel base?