When you're hit with crosswinds from passing trucks or on bridges, etc. the wind seems to want either to knock you over or steer you across lanes and into the bushes (or oncoming traffic).
The trick is to make the wind meet you on your terms. Try and picture instead the wind blowing the bike "out from under you," and not toppling you over, or changing your course. It sounds wrong, I know, but having the bottom of the bike (the wheels actually) move away from the wind while your head stays in a pretty straight line, means that you are now "banked" as if going into a turn. This rapid, short, banking against the wind counterbalances the wind's force and keeps you going in a straight line. Think of it kinda like a skier on the slolem - his skis go out to the side but his upper body stays over the line of where he wants to go.
The "slolem" move is what we practice as "swerving." I'll do this on an empty rural road, picking something to avoid like a manhole cover or a different color spot on the pavement and throw the bike out from under me so that it counters to the other side, then reverse the move from one side to the other, like the skier. Getting familiar with this feeling will prepare you for a faster, more automatic response time when the wind gusts hit.
good luck, enjoy.
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