Road rash from a cycling crash is not an especially deep injury, but it can bleed and is definitely painful. If the abrasion is large, see a doctor. Otherwise, treat it at home with these tactics.
Clean the area with a mild soap and water. Abrasions like these are loaded with dirt from whatever surface it was that you dragged yourself across. Scrub gently—you don’t want to cause any more damage. If you can’t scrub it because it hurts too much, try pouring soapy water over it. Use tweezers to remove any gravel. Oh, and take an NSAID like ibuprofen or naproxen to help with the throbbing, because this will hurt.
Apply a layer of triple-antibiotic ointment (like Neosporin) to the entire area. It’s also helpful to apply a layer of petroleum jelly on top of that to prevent the bandage from sticking to the flesh. Cover it with a sterile gauze pad and tape. Change the dressing once a day. It will be gooey and ooze, which is nasty but normal. Big abrasions usually heal from the deeper layers of the skin outward, and also from the edges toward the center. If the bandage sticks to the wound, don’t try to pull it loose. Soak it in the bathtub for about 20 minutes and it should come off easily.
If you see redness and swelling, and the wound feels hot or secretes pus, it could be infected. See a doctor.