Next time you come to a patch of cracked or bumpy road that promises to rattle you uncomfortably, there are a couple of different techniques you can employ to help lessen the effects of that bad pavement and "float" over the rough stuff:
1. Move your hands to the bar top, bend and relax your elbows, and lean forward a bit.
This posture lets your arms absorb the chatter before it reaches your torso. And it lightens your weight on the saddle.
Always grip the bar with your thumbs around it, not resting on top. This is smart all the time, not just on rough roads. It prevents your hands from accidentally slipping off and maybe causing a crash.
You can coast through brief sections of rough road with your elbows and knees flexed, or pedal through longer sections. When pedaling, use a slightly bigger gear than normal to reduce bike chatter and put more weight on your feet, less on your seat.
If the rough patch that you're about to traverse looks to be even worse, or you see one significant bump in your path, and you're able to coast over it with no need to pedal, you might benefit from a bit different position.
2. With your hands on the hoods or in the drops (wider on the bar for more control), bend and relax your elbows and lean forward, just as in the previous position. This time, though, push up with your legs and rise off the saddle completely to remove your butt as a contact point, keeping your knees flexed to help absorb the bigger bump(s).
Doing so will allow the road chatter to filter through your elbows and arms, knees and legs and help mitigate the effect of the rough patch.