For a standard race day, the Paul Rodriquez Duffel will fit all gear necessary:
The bag has been with me every weekend this year, has been to New York, Los Angeles, Barcelona, and France. It's padded walls and exterior nylon have kept my fragile items like laptops and helmets protected against overhead compartments in airplanes and crammed car trunks en route to races. Having a bag that is big enough to fit a helmet and padded enough to protect it is crucial! The handles double as backpack straps (removed in photo above) when you need to ride your bike and carry your gear to the race. The entire bottom of the duffel zips away to reveal another compartment, a large space useful for soiled kits:
As seen above, there are ample pockets throughout the bag, each of which can be designated for tools, books, greasy rags, or whatever suits you. I highly recommend the Paul Rodriquez Duffel as your race bag!