[Andrew Blair]

I'd like to stress that, as Sanddrag and Travis pointed out, proper alignment and tensioning is crucial. We've used #25 practically forever, and had great success- and failure. #25 is almost entirely suitable as far as FIRST goes in terms of actual chain tension loading. What the motors put out, stopping and starting forces- the chain can handle the tension forces well.

However, #25 will quickly inform you if there is *any* misalignment, angular or lateral, mis-tensioning, or other problems. Last year, even with properly tensioned, aligned, and lightly loaded chain, if we ran over a ball, we crossed our fingers!

Regionals can be a humbling and frustrating experience should you screw up- mechanical reliability is paramount, and badly implemented #25 *will* cause problems there. We broke ~6 chains at Pittsburgh last year, and paid the price. Limping robots are bad robots. However, we tensioned and protected the chains better, and had a great success rate.


As Travis said, you must evaluate each case individually and weigh the consequences. You save huge amounts of weight using #25, but it's very important to design the system well. It will not hold up to running barriers over, or rubbing against a bent frame, or dealing with the mis-alignment caused by that bent frame. But I don't want to get too down on #25; we love it! It saves so much weight, and when properly implemented, won't give you any headaches. Just be careful!