[Jim Zondag]

I totally agree, #25 chain is more than adequate. We have used #25 chain in our Drivetrains for years and never had any issues (providing that everything is assembled correctly). #25 chain will not break until you put over 900 lbs of tension on it. It is pretty much impossible to apply this level of force in a FIRST robot drivetrain.

The 3 main issues I see team have with #25 chain are:
1. Alignment - If you don't line up your sprockets you will have issues
2. Frame Rigidity - If your frame is not bolted together tightly, things will come out of alignment when torque is applied.
3. Workmanship - I see lots of teams who mangle #25 chain when removing links. This can create a stiff spot in the chain where it will not bend properly. This will make it more likely to derail. It is much harder to do this to #35.

So basically, the advantage of #35 is that it allows you to be sloppier in your design and fabrication. If you pay close attention to these details, you will never have a problem with #25 chain.