What is the best way to treat abrasions from motorcycle crash without going to er?

Very carefully: You have to be sure that you have every bit of debris from the road out of the rash, and this is hard to do if it is swollen and painful without an anesthetic. Try doing it under running water, cold alternating with very warm. Also, you need a tetanus shot if you haven't had one in 10 years. If redness, pain increase or if you get fever, you should see someone to get antibiotics.