If you can afford it, get two pair of wheels--a light pair just for racing, and a durable pair for training. Use the same cogs (they're easy to switch from one rear wheel to the other) to avoid chain/cog incompatibility.
Six Product Picks for Optimum Triformance Life's too short to get bored or burned-out doing one sport dayafter day. Going the swim-bike-run route will producethe kind of full-body fitness that single-sport athletes can neverachieve.