Originally Posted by elgalad

With regard to weaving, how fast are you going when this starts to happen? If you're going really slowly (maybe 5-6 mph), then this could be the cause. Otherwise, try and lean forward a little bit. A good rule of thumb is to have your head directly above the intersection of the stem and handlebars, and try and get a rhythm going, with the bike rocking gently back and forth through 9-12 inches of arc. Again, this will be easier if you're pushing a bigger gear at lower cadences.