Most definitely hun I say after about 3-4 weeks you will start to notice a difference. I really like to do squats that really firms up my butt and thighs.
It will definitely get rid of the cellulite, but it will not tone you buttocks and thighs much.A bike is intense enough to raise you heart rate high enough for your body to start burning fat off your body and make the cellulite go away but its not enough for firm the muscles in those areas.You should add weight training for those areas also.Although, I suggest you do weight training for the whole body. It burns more fat that way and tones everything else. Worst comes to worst, you ll look better :PCheers :)
Riding a bike will help but, roller blading, in-line or ice skating would do a better job. This activity uses all the right muscles to work the glute and thighs, plus its fun.