[GeeTwo]

If you're committed to this layout, and you're using one chain per side as is most common, I suggest putting the CoG significantly towards the axle which is not coupled by chain to the center wheel, and note that you will get your best acceleration away from that axle.

Try to find some way to increase the center drop. As I noted above, recall that the center axle is already a dead axle; don't be shy about using cover plates, putting a bolt through them, and mounting your wheels on bearings to accomplish this.

The team had already bought the nano tube for our air cannon before I became seriously involved. Looking at it later, this seems to me to be a great way to mount mecanum if you can get the right gear ratio, but for anything else it leaves much to be desired.