Whoa, this seems like about the ninetieth time I've answered this.
In FIRST, more often than not, #25 is quite adequate- almost never breaking or giving problems- if it's tensioned and aligned very well. If not, you're playing roulette, and it will fail, at some point. Maybe sooner, maybe later, maybe seven times at the Pittsburgh regional in 2006.
My suggestion, use #35 from the gearbox to your first wheel, and then you can use #25 after that. If it breaks, you're still moving.
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