You might take a look at "Portfolio Watch" in the menu of account options at Vanguard. It walks through your assets at Vanguard in many different ways. For example, it will tell you if you favor small cap, or if your (non-existent) bond allocation is too short term or differs from the market.
The closer you get to your retirement goal, the more valuable it becomes to keep your money rather than risk it. I'd suggest you at least allocate 10% to bonds - just because it's a better habit, and unlikely to have much impact on your portfolio. As you get older it will help you to already have bonds and already have the habit of selling stocks to buy bonds (when stocks do better).