As a general rule, you want to avoid putting your hands out. That's a good way to beat up your hands and transmit energy straight to your collar bone.
If you can, much better to pull your body into a ball and roll. You'll still get road rash, but you're less likely to break things.
With all that said, if you have time to think about how to fall, you're probably better off not falling. But if your first reaction is to wad yourself up on a ball and use your shoulders and hips (areas with big muscles) as shock absorbers, you're doing it right, in my limited experience.
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Formerly fastest rider in the grupetto, currently slowest guy in the peloton
