You really should ask a Retinal -Vitreal specialist. I'm at some risk of a detachment and have been told to avoid all out efforts like lifting very heavy objects or running or biking at an all out effort. Gravel racing requires you to make an all out effort. I know that hard shocks to the head can cause retinal detachments, but I don't know about continuous vibrations. I guess its up to you decide how important is recing, and is it worth risking your eyesight.