Galaxy,

This thread has been inactive for 2 years.

Regarding sub-concussive impacts, unless you are riding down a very rough road for a substantial period of time, I doubt your are sustaining any sub-concussive damage. If you drive the same route to work every day, you should be able to plan to avoid or do other things to lessen the intensity of these rough spots. Try to avoid riding with your back rigidly against the back of the seat. Foam seat cushions could help.

And, lighten up on your anxiety over sub-concussive impacts.