9mm belt vs 15mm belt

[cadandcookies]

As a general rule, 9mm belts are sufficient (source: I've designed and built two FRC robots that used 9mm belts-- GT2 and HTD), however if you're a cautious type, or if you're planning to push the limits of the belts (What are those, you ask? Check out the Gates website!), 15mm is "safer." Certainly it feels a lot more comfortable.

In my opinion, if this is an offseason drive, it's not a particularly huge deal which one you pick-- if your team has always used chain, there's plenty of new things to adapt to without worrying about your belt choices. Once you have a grasp on thinking with portals designing with belts, then you can start worrying more about what kind of belt best fits your application.