This was our first year attempting belts, and even though we encountered some hurdles, it's very likely we'll be using them again next year. We went with a 15mm wide, 5mm pitch GT2 profile belt from GATES, with 32 tooth pulleys on all the wheels. We took a serpentine approach for the belt path with power driven through the middle wheel; the belt is on the outside of the frame for ease of maintenance. After some testing, we put in an additional tensioner (on the left) to take up some of the slack from our imprecise tolerances and the deflection we saw in the fiberglass frame material.
We did see some belt skipping on the middle pulley on the practice bot, most likely a combination of the low belt engagement and the deflection of the cantilevered idlers when under load. Fiberglass is flexy stuff! We'll likely be switching to aluminum for the drivetrain next year if we use belts again. I'd be wary of designing to exact dimensions if a serpentine approach is taken... we'll probably be using a tensioner next year as well.
The belts served us well in our first regional. No issues with the drivetrain, and the minimal backlash let us pull off some
neat autonomous maneuvers.