I think its been said a few different ways and a few times, but the simple fact is people like that HAVE to pick on you because they know your being superior. you might be fat, I am, I was at the beginning of the year "morbidly obease"
when people of low self esteem see people trying to better themselves there is a strong desire to keep that person from accomplishing their goals, thus proving we are all the same loser failures they are. you must remember that the bottom line is they aren't putting you down they are trying to keep you down with them. Just like any hill your challenged with, remember your better than it is and you will make it to the top(sometimes you walk, sometimes you ride, but either way you made it)
you cannot forget that the human condition calls for dominance, and you are making people who are too lazy or stupid to better themselves jealous of your drive and determination. if you keep thinking of them in this light, I can smile every time knowing every rotation is me pulling away from them, fat or not I am bettering myself, what did they do today?
"I'm sorry you didn't accomplish your goals, don't take it out on me." dont say it, they aren't worth the breaths, but the fact remains this is where it stands. if you bothered to say it you would probably realize they were too stupid to understand how true it was.
You are better than them, you don't need to worry about what they think, your already winning that race. good luck and happy riding.