don't worry about people like that - they are most likely insecure and try to bolster themselves by putting down others.
Just take that pink bike out and show them what you're made of. At 5' tall and a little over 100 lbs, I do not cut an imposing figure by any stretch of the imagination and I often hear comments about my "cute little bike", but most people find rather quickly that it does not pay to underestimate me - I won 3 state championship medals this year