[RoboChair]

I would not use #35 chain for pretty much anything on a robot, it is heavy and way stronger than it has any business being on a drivetrain. Working load(not breaking strength) on #25 chain is 88 pounds vs. 199 pounds for #35. I'm not sure what the safety factor on ANSI chain is, but I know that the 6 CIM drivetrain we had on our 2014 robot used #25 chain(the heavier duty VEX stuff with thicker side plates) and required very little maintenance nor suffered adversely from stretching.

15 fps in high gear is slow, very very slow for a 6 CIM drivetrain considering you are likely to lose 10% or more mechanical efficiency, leaving you in the 13 fps range. Our 2014 bot was geared to a theoretical 22 fps and we measured our actual top speed at just over 18 fps(18% efficiency loss). We likely could have geared it a little slower and gotten our top speed a little faster, maybe 19 fps. So I know you can reasonably push the top gear 10%-25% higher, the only reason to keep it in the geared to 15 fps range would be if you need rapid bursts of acceleration to cover sub-20ft range movements on the field.