It depends on what type of racing you want to do. In bike racing, some of the different types of racing are:
1) road (road races, time trials, criteriums) Triathlon could also be in here.
2) mtb (cross country, downhill, slalom and four cross
3) cyclocross
4) bmx
5) track (fixed gear, you can't coast!)
If you can be more specific, I am happy to help. What type of racing? You looking for brands? What's your budget and experience?
If you are in the market, your best option is to go into your LOCAL bike shop and find an experienced and knowledgable sales person. This way, you can test different types/brands of bikes, and then they can help you with all service needs, like customizing the fit, and doing tune-ups in the future.