[nathan_hui]

Looks like a nice chassis. However, here are some questions/issues to consider:

Are your center wheels dropped? It's hard to see from the render...
If they are, is it enough to turn (you're currently back heavy - the robot, as is, will have a tendency to essentially be a 4WD)?

Again, the bracing - it looks like a tap at the corners going sideways will collapse your chassis.

I noticed an unusual pattern in your front bracket - the hole pattern on the top doesn't seem to be regular. Design feature? Also, if, for some odd reason, you plan to mount a structural element for the rest of the robot right in the middle of the front bracket, what prevents the bracket from collapsing down?

Is there provision for chain tensioning (that's the question that kills my chassis designs over and over again)?

Is there a particular reason for the non-direct drive design choice? You now have a single point of failure in the chain going from the gearbox to your first wheel. Remember that when you use master links, you need to design for a FOS of at least 6.

Does the chassis need to that thick? Having the wheels in a well is good for aesthetics, but when it comes time to maintain the drivetrain, that's just a hassle. As you make the chassis thinner, you reduce the amount of chain you need (thus removing a lot of steel from the drivetrain). You also reduce CG, and increase the amount of vertical volume for the rest of the robot.